Proceedings of the 9th U.S.-Japan Natural Resources 

Panel for Earthquake Research

Edited By Shane T. Detweiler and William Ellsworth

Open-File Report 2014–1250 

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

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Detweiler, S., and Ellsworth, W., eds., 2015, Proceedings of the 9th U.S.-Japan natural resources panel for 

earthquake research: U.S. Geological Survey Open-File Report 2014–1250, 89 p. 

http://dx.doi.org/10.3133/ofr2014. 

ISSN 2331-1258 (online)
i 

TABLE OF CONTENTS 

Introduction____________________________________________________________1

Agenda________________________________________________________________2

Session I Abstracts______________________________________________________7

Yuki Hatanaka “Interplate coupling on and around the focal area of the 2011 off the Pacific 

Coast of Tohoku Earthquake, Japan”_________________________________________8

Fred Chester “Location and structure of the subduction thrust in the region of maximum slip 

during the 2011 MW 9.0 Tohoku-Oki earthquake”_____________________________10

Toshiya Fujiwara “Coseismic fault rupture reaching the trench axis during the 2011 Tohoku-Oki 

earthquake”___________________________________________________________12

Mark Simons “The 2011 Tohoku-Oki earthquake and the Advanced Rapid Imaging and Analysis 

(ARIA) Project for Natural Hazard Monitoring and Response”____________________14

Makoto Matsubara “The 2011 Tohoku-oki Earthquake related to a strong velocity gradient 

within the Pacific plate”__________________________________________________16

Shuo Ma “Uncovering the Mysteries of Tsunami Generation and Anomalous Seismic Radiation in 

the Shallow Subduction Zone”_____________________________________________19

Yasuto Kuwahara “Stress states before and after the 2011 Great Tohoku earthquake in and 

around the focal region”__________________________________________________21

Eileen L. Evans and Brendan J. Meade “Geodetic imaging of coseismic slip and postseismic 

afterslip: Sparsitypromoting methods applied to the great Tohoku Earthquake”_____23

Takashi Saito “GSI activities in response to the 2011 off the Pacific coast of Tohoku 

Earthquake”___________________________________________________________24

Session II Abstracts____________________________________________________26

Art Frankel “USGS Seismic Hazard Mapping Efforts: U.S. National Seismic Hazard Maps and 

Urban Seismic Hazard Maps Based on 3D Simulations”_________________________27

Koshun Yamaoka “National Policy and Project on the Earthquake Research after the 2011 Off 

the Pacific Coast of Tohoku Earthquake”_____________________________________30
ii

Margaret Glasscoe “E-DECIDER: Experiences Developing Earthquake Disaster Decision Support 

and Response Tools”_____________________________________________________32

Hiroyuki Fujiwara “Some considerations for improvement of the National Seismic Hazard Maps 

for Japan”_____________________________________________________________34

Morgan Moschetti “Time-independent earthquake forecasts for the Intermountain West, 

United States” ____________________________________________________36

Session III Abstracts____________________________________________________38

Bruce Jaffe “Assessing Tsunami Hazard from Paleotsunami Deposits”____________________39

Masanobu Shishikura “Strategy for evaluating giant earthquake and tsunami by coastal 

paleoseismology”_______________________________________________________40

Takeshi Koizumi “JMA's response to the 2011 off the Pacific coast of Tohoku Earthquake and 

planned Improvements of Tsunami Warning”_________________________________42

Session IV Abstracts____________________________________________________44

Dominic Asimaki “Nonlinear site and topography effects in ground motion predictions: 

Observations, Hypotheses and Lessons to be learned”__________________________45

Shin Aoi “Strong motion characteristics of the 2011 Tohoku-Oki earthquake observed by K-NET 

and KiK-net”___________________________________________________________47

Lisa Grant-Ludwig “Reconciling precariously balanced rocks with large earthquakes on the San 

Andreas fault system”____________________________________________________49

Session V Abstracts_____________________________________________________50

Jeremy Zechar “Betting against the house and peer-to-peer gambling: a Monte Carlo view of 

earthquake forecasting”__________________________________________________51

Kohei Nagata “Information services on earthquake prediction and forecast of JMA”________52

Yasuyuki Yamada “Earthquake Early Warning of JMA- The 2011 off the Pacific coast of Tohoku 

Earthquake and its aftershocks”____________________________________________54

John Vidale “Early Warning on the US West Coast”___________________________________56
iii

Session VI Abstracts____________________________________________________57

David Chadwell “Potential contributions of Seafloor Geodesy to understanding slip behavior 

along the Cascadia Subduction Zone”_______________________________________58

Sarah Minson “Performance Tests of Real-Time Permanent Displacement Estimates and Rapid 

Rupture Characterization From Real-Time High-Rate GPS”_______________________60

Andrea Donnellan “Integrating GPS and Radar Geodetic Imaging Observations with Models for 

Earthquake Response and Planning Additional data Collection”___________________61

Ken Xiaosheng Hao “Rapid assessment of high seismic intensity areas for mega-earthquake 

using satellite SAR data”__________________________________________________62

Gavin Hayes “Real-Time Monitoring at the USGS National Earthquake Information Center: Past, 

Present, Future”________________________________________________________64

Charles Estabrook “NSF's EarthScope Program – Introduction and Updates”_______________66

Poster Session (Session VII) Abstracts_____________________________________67

Shin Aoi “Ocean bottom seismic and tsunami network along the Japan Trench”____________68

Satoshi Kawamoto (presented by Dr. Yuki Hatanaka) “Developing a GEONET Real-time 

Processing System for Rapid Earthquake Modeling”____________________________70

Yasuto Kuwahara “Asia-Pacific Region Global Earthquake and Volcanic Eruption Risk 

Management (G-EVER) project”____________________________________________72

Session VIII Abstracts __________________________________________________74

David Shelly “Dynamics of Migrating Earthquake Swarms at Yellowstone and Mount Rainier 

Volcanic Areas: Evidence for Fluid Triggering?”________________________________75

Takuya Nishimura “Detection of short-term slow slip events along the Nankai trough, southwest 

Japan using GNSS data”__________________________________________________76

Yehuda Bock, Brendan Crowell, and Diego Melgar “Mitigation of Earthquake Hazards with a

 Seismogeodetic Model as Demonstrated for the 2011 Mw 9.0 Tohoku-oki Earthquake”_78

Norio Matsumoto “Short-term slow slip events in the Kii peninsula by joint analysis of the AIST 

borehole strainmeter array and the NIED Hi-net tiltmeter array”__________________79
iv

Bunichiro Shibazaki “3D quasi-dynamic modeling of cycles of megathrust earthquakes along the 

Japan Trench subduction zone considering high-speed friction”__________________80

Wayne Thatcher “Advantages and Limitations of Cluster Analysis in Interpreting Regional GPS 

Velocity Fields in California and Elsewhere”__________________________________81

Kazushige Obara “Characteristic activity of tremor as proxy for slow slip in the transition zone 

along the subducting plate interface”_______________________________________83

Justin Rubinstein “Repeating Earthquakes on the Parkfield Segment of the San Andreas: 

Do They Reload Themselves?”_____________________________________________85

Keynote Talk Abstracts _________________________________________________87

David Wald “Earthquake loss modeling on a global scale: balancing empirical & physics-based 

approaches”___________________________________________________________ 88

Meghan Miller “UNAVCO: Recent Earthquake Responses, Multi-hazard Networks, and 

Technology Development” _______________________________________________89
1 

Introduction 

The UJNR Panel on Earthquake Research promotes advanced study toward a more fundamental 

understanding of the earthquake process and hazard estimation. The Ninth Joint meeting was 

extremely beneficial in furthering cooperation and deepening understanding of problems 

common to both the U.S. and Japan. 

The meeting included productive exchanges of information on approaches to systematic 

observation and modeling of earthquake processes. Regarding the earthquake and tsunami of 

March 2011 off the Pacific coast of Tohoku, the Panel recognizes that further efforts are 

necessary to achieve our common goal of reducing earthquake risk through close collaboration 

and focused discussions at the 10th UJNR meeting. We look forward to continued cooperation 

on issues involving the densification of observation networks and the open exchange of data 

among scientific communities. We recognize the importance of making information publicly 

available in a timely manner. We also recognize the importance of information exchange on 

research policy and strategies, including the frameworks of research organizations. 

Areas of Cooperation 

Specific areas of earthquake research where cooperative research between the U.S. and Japan 

may lead to significant advancement include, but are not limited to: 

Probabilistic earthquake and tsunami hazard estimation, including extraordinarily large 

earthquakes, both in our respective countries and worldwide, incorporating knowledge of 

current and past behavior, and physics based computational models; 

Real-time information from seismic, geodetic and strain measurements, including 

borehole strainmeters and seafloor observations using offshore cabled networks; 

Technologies for measuring crustal deformation; 

Early warning technologies for earthquakes and tsunamis; 

Studies of recurrence of large and extraordinary large earthquakes using paleoseismic, 

paleotsunami, geodetic and seismic methods; 

Laboratory, theoretical and in situ studies of fault-zone processes; 

Studies of episodic tremor and slow slip events using seismic, geodetic, and borehole 

strain measurements, and simulation techniques; 

Systematic studies of earthquake predictability through rigorously evaluated scientific 

prediction experiments and robust databases; 

Studies of near-source ground motions, geological effects and the response of engineered 

structures. 

The Panel strongly urges that the appropriate agencies in the U.S. and Japan that are represented 

on this panel work together with the academic sector to support and coordinate scientific work in 

these areas of cooperation. The Panel recognizes the importance of promoting the exchange of 

scientific personnel, exchange of data, and fundamental studies to advance progress in 

earthquake research. The U.S. and Japan should promote these exchanges throughout the world. 

The Panel endorses continuation of these activities. 
2

9

th UJNR Panel on Earthquake Research 

Denver, CO 

October 9-12, 2012 

Meeting Agenda 

Tuesday, Oct. 9

0800 Registration 

0830 Welcoming Remarks by Panel Co-Chairs David Applegate and Kazuo Inaba

0900 Opening Session- Session Chairs Toshiya Fujiwara and Shuo Ma

The 2011 off the Pacific Coast of Tohoku Earthquake and lessons learned 

Yuki Hatanaka “Interplate coupling on and around the focal area of the 2011 off the 

Pacific Coast of Tohoku Earthquake, Japan”

0920 Fred Chester “Location and structure of the subduction thrust in the region of maximum 

slip during the 2011 MW 9.0 Tohoku-Oki earthquake”

0940 Toshiya Fujiwara “Coseismic fault rupture reaching the trench axis during the 2011 

Tohoku-Oki earthquake”

1000 Break 

1020 Session 1 (cont.) 

Mark Simons “The 2011 Tohoku-Oki earthquake and the Advanced Rapid Imaging and 

Analysis (ARIA) Project for Natural Hazard Monitoring and Response”

1040 Makoto Matsubara “The 2011 Tohoku-oki Earthquake related to a strong velocity 

gradient within the Pacific plate”

1100 Shuo Ma “Uncovering the Mysteries of Tsunami Generation and Anomalous Seismic 

Radiation in the Shallow Subduction Zone”

1120 Yasuto Kuwahara “Stress states before and after the 2011 Great Tohoku earthquake in 

and around the focal region”

1140 Brendan Meade “Geodetic imaging of coseismic slip and postseismic afterslip: Sparsity 

promoting methods applied to the great Tohoku Earthquake”

1200 Takashi Saito “GSI activities in response to the 2011 off the Pacific coast of Tohoku 

Earthquake” 

1220 Break for lunch set-up
3

1250 Lunch 

Keynote Address: 

David Wald “Earthquake loss modeling on a global scale: balancing empirical & physicsbased approaches”

1420 Break for lunch take-down 

1450 Session 2: Session Chairs Koshun Yamaoka and Art Frankel 

Earthquake Hazard Studies, Recurrence, and Map Updates 

Art Frankel “USGS Seismic Hazard Mapping Efforts: U.S. National Seismic Hazard Maps 

and Urban Seismic Hazard Maps Based on 3D Simulations”

1510 Koshun Yamaoka “National Policy and Project on the Earthquake Research after the 

2011 Off the Pacific Coast of Tohoku Earthquake”

1530 Margaret Glasscoe “E-DECIDER: Experiences Developing Earthquake Disaster Decision 

Support and Response Tools”

1550 Hiroyuki Fujiwara “Some considerations for improvement of the National Seismic 

Hazard Maps for Japan”

1610 Morgan Moschetti “Time-independent earthquake forecasts for the Intermountain 

West, United States”

1630 Break 

1650 Session 3: Session Chair Takeshi Koizumi 

Probabilistic Earthquake and Tsunami Hazard Estimation, Paleoseismology and 

Paleotsunamis 

Bruce Jaffe “Assessing Tsunami Hazard from Paleotsunami Deposits”

1730 Masanobu Shishikura “Strategy for evaluating giant earthquake and tsunami by coastal 

paleoseismology”

1750 Takeshi Koizumi “JMA's response to the 2011 off the Pacific coast of Tohoku Earthquake 

and planned Improvements of Tsunami Warning”

1810 Discussion

1830 Adjourn/Reception Banquet

Wednesday, Oct. 10

0900 Opening Comments 

0910 Session 4: Session Chairs Dominic Asimaki and David Wald

Studies of Near-Source Ground Motions 
4

Dominic Asimaki “Nonlinear site and topography effects in ground motion predictions: 

Observations, Hypotheses and Lessons to be learned”

0930 Shin Aoi “Strong motion characteristics of the 2011 Tohoku-Oki earthquake observed by 

K-NET and KiK-net”

0950 Lisa Grant-Ludwig “Reconciling precariously balanced rocks with large earthquakes on 

the San Andreas fault system”

1010 Break 

1030 Session 5: Session Chairs John Vidale and Kohei Nagata

Operational Earthquake Forecasting and Earthquake Early Warning System 

Development 

Jeremy Zechar “Betting against the house and peer-to-peer gambling: a Monte Carlo 

view of earthquake forecasting”

1050 Kohei Nagata “Information services on earthquake prediction and forecast of JMA”

1110 Yasuyuki Yamada “Earthquake Early Warning of JMA- The 2011 off the Pacific coast of 

Tohoku Earthquake and its aftershocks”

1130 John Vidale “Early Warning on the US West Coast”

1150 Break for lunch set-up

1220 Lunch 

Keynote Address: 

Meghan Miller “UNAVCO: Recent Earthquake Responses, Multi-hazard Networks, and 

Technology Development” 

1350 Break for lunch take-down 

1420 Session 6: Session Chairs Ken Xiaosheng Hao and Sarah Minson 

Real-time Monitoring of seismic, geodetic and strain measurements, Seafloor GPS 

David Chadwell “Potential contributions of Seafloor Geodesy to understanding slip 

behavior along the Cascadia Subduction Zone”

1500 Sarah Minson “Performance Tests of Real-Time Permanent Displacement Estimates and 

Rapid Rupture Characterization From Real-Time High-Rate GPS”

1520 Andrea Donnellan “Integrating GPS and Radar Geodetic Imaging Observations with 

Models for Earthquake Response and Planning Additional data Collection”

1540 Break 
5

1600 Ken Xiaosheng Hao “Rapid assessment of high seismic intensity areas for megaearthquake using satellite SAR data”

1620 Gavin Hayes “Real-Time Monitoring at the USGS National Earthquake Information 

Center: Past, Present, Future”

1640 Charles Estabrook “NSF's EarthScope Program – Introduction and Updates”

1700 Discussion

1720 Session 7: Poster Session 

Shin Aoi

“Ocean bottom seismic and tsunami network along the Japan Trench”

Satoshi Kawamoto (presented by Dr. Yuki Hatanaka) 

“Developing a GEONET Real-time Processing System for Rapid Earthquake Modeling 

Yasuto Kuwahara

“Asia-Pacific Region Global Earthquake and Volcanic Eruption Risk Management (G-EVER) 

project”

1800 Adjourn/Meet for informal dinner

Thursday, Oct. 11

0900 Opening Comments 

0910 Session 8: Session Chairs Justin Rubinstein and Takuya Nishimura 

Episodic Tremor and Slow Slip, in situ Studies of fault-zone Physics 

David Shelly “Dynamics of Migrating Earthquake Swarms at Yellowstone and Mount 

Rainier Volcanic Areas: Evidence for Fluid Triggering?”

0930 Takuya Nishimura “Detection of short-term slow slip events along the Nankai trough, 

southwest Japan using GNSS data”

0950 Diego Melgar “Mitigation of Earthquake Hazards with a Seismogeodetic Model as 

Demonstrated for the 2011 Mw 9.0 Tohoku-oki Earthquake”

1010 Norio Matsumoto “Short-term slow slip events in the Kii peninsula by joint analysis of 

the AIST borehole strainmeter array and the NIED Hi-net tiltmeter array”

1030 Break 

1050 Session 8: (cont.) 
6

Bunichiro Shibazaki “3D quasi-dynamic modeling of cycles of megathrust earthquakes 

along the Japan Trench subduction zone considering high-speed friction”

1110 Wayne Thatcher “Advantages and Limitations of Cluster Analysis in Interpreting 

Regional GPS Velocity Fields in California and Elsewhere”

1130 Kazushige Obara “Characteristic activity of tremor as proxy for slow slip in the transition 

zone along the subducting plate interface”

1150 Justin Rubinstein “Repeating Earthquakes on the Parkfield Segment of the San Andreas: 

Do They Reload Themselves?”

1210 Discussion

1230 Closing remarks and Presentation of Meeting Resolution by Panel Co-Chairs David 

Applegate and Kazuo Inaba

1240 Group photo 

1310 Lunch 

1410 Depart for field trip to Golden, CO 

1430 Arrive Golden, CO, Tour USGS- National Earthquake Information Center 

1700 Free time in Golden, CO. Dinner on own. 

2000 Return to hotel 

2030 Arrive Hotel 

Friday, Oct. 12

0900 Board bus- Depart for field trip 

1015 Arrive Boulder, CO, Tour UNAVCO Facility 

1230 Box Lunch in Boulder 

1330 Depart for Denver, CO 

1430 Arrive Country Inn Hotel, Free time 

1500 Arrive Sheraton Hotel, Free time 
Session I 

Abstracts 

7
Interplate coupling on and around the focal area of the 2011 off the Pacific 

Coast of Tohoku Earthquake, Japan 

Yuki Hatanaka, Shinzaburo Ozawa, Takuya Nishimura, and Hisashi Suito 

Geography and Crustal Dynamics Research Center, Geospatial Information Authority of Japan 

Interplate coupling and coseismic slip of the 2011 off the Pacific Coast of Tohoku Earthquake 

were estimated based on nearly 18-years-long data of the GEONET, a continuous GNSS network 

of Japan. 

In the period before the 2011 off the Pacific Coast of Tohoku Earthquake, Japan, shortening in 

east-west direction due to the push by the subducting Pacific plate was main characteristics of the 

crustal deformation in northeastern Japan. The analysis of GEONET data from 1997 to 1999 shows 

a large slip-deficit rate off Miyagi prefecture. The EW shortening rate became slower in

Fukushima prefecture after 2000, suggesting partial weakening of interplate coupling in progress. 

The 2011 off the Pacific Coast of Tohoku Earthquake ruptured the large area from the off Iwate 

prefecture to off-Chiba prefecture. An extremely large slip is found at a shallow portion of the plate 

boundary off Miyagi prefecture. The rupture extends to a deeper potion near Miyagi prefecture 

than off Fukushima prefecture. The north end of the rupture area is close to the rupture area of the 

1994 far off Sanriku earthquake. The slip is relatively small off Fukushima where the partial 

unlocking was inferred before the main-shock. These facts suggest the effect of the preceding 

aseismic slip on the rupture process of the main-shock. 

The main-shock was followed by large postseismic deformation. We assume an afterslip was a 

main mechanism of the observed deformation and estimated a distribution of the afterslip. The slip 

areas of the main shock and the afterslip tend to avoid overlapping. The afterslip is taking place 

mainly at a deeper portion of the plate boundary than the main rupture. The afterslip in off-Miyagi 

prefecture, where the coseismic slip was very large, is smaller than that of the northern and 

southern areas. The moment magnitude (Mw) of the afterslip is nearly 8.6 as of September, 2012. 

Continuous monitoring of the after-slip is important to understand the cycle of the huge 

earthquakes since it is revealing the rebuilding process of interplate coupling for the next 

earthquake. Since the main rupture took place at the offshore area near the trench, where resolving 

power of GEONET data is low, collaboration with an offshore crustal deformation observation is 

especially important. 

8
Figure 1. (a) Distributions of slip-deficit rates on the two plate boundaries for Period 1 (October 1997 to 

October 1999). The thick rectangle on the Pacific side is the fault model region of the subducting Pacific plate. 

The contour interval is 2 cm/yr. Gray areas represent regions of forward-slip. The heights of bars in the Japan Sea 

reflect the rate of collision at the plate boundary modeled by the virtual tensile fault. Stars are the epicenters of 

large earthquakes with magnitudes of ≥6. The broken lines are isodepth contours of the plate interface. (b) Same 

as (a) but for Period 2 (October 2008 to October 2010). (c) Slip distribution of the 2011 Tohoku-Oki earthquake, 

from the Geospatial Information Authority of Japan (2011). Thick and thin lines represent coseismic slip 

distributions estimated from land and offshore GPS data and postseismic slip distributions, respectively, for ~4 

months. The gray region with the broken line represents the source area to the 1994 Far east off Sanriku 

Earthquake (Nishimura et al., 2000) (after Nishimura, 2012). 

Figure 2. Transient time series of E-W component at 

selected stations along the Pacific coast of northeastern 

Japan. Exponential functions are also indicated in 

brown, green, and blue lines, which correspond to the 

2005 Miyagi, 2008 Fukushima, and 2010 Fukushima 

earthquakes, respectively, at the stations mentioned in 

the text. Vertical broken lines indicate the date of the 

earthquakes whose epicenters are shown in (a) as red 

stars (after Suito et al., 2012).

9
Location and structure of the subduction thrust in the region of maximum slip 

during the 2011 MW 9.0 Tohoku-Oki earthquake

Frederick M. Chester (Texas A&M University, USA), James J. Mori (Kyoto University, Japan) 

Nobu Eguchi (CDEX / JAMSTEC, Japan), Sean Toczko (CDEX / JAMSTEC, Japan) 

and Expedition 343 and 343T Scientists* 

The fault slip during the 11 March 2011 Tohoku-Oki earthquake, which reached a maximum of 

>50 m near the Japan Trench, was the largest ever observed for an earthquake and was 

responsible for the peak tsunami heights of 20 to 40 meters that struck the coast of northeast 

Honshu (Figure 1). Although the cause of such large seismic slip at shallow depths is not entirely 

understood, a number of possible contributing factors have been identified. These include 

heterogeneous coupling up dip of the hypocenter or other factors that generate an energetic 

rupture to drive shallow slip, a compliant wedge and the free surface above a shallow thrust fault 

that magnifies overshoot, widespread poroplastic failure of the wedge that produces uplift and 

diminishing slip towards the trench, and friction behavior of the shallow subduction thrust that 

promotes earthquake rupture propagation even though inhibiting rupture nucleation. Outstanding 

questions include how displacement was accommodated near the trench, and whether coseismic 

weakening of the shallow megathrust had a role in the mechanics of such large displacement. 

These and other questions are being addressed with data from the recently completed rapidresponse expedition (Expedition 343 and 343T) undertaken by the Integrated Ocean Drilling 

Program (IODP). 

a. b.

Figure 1. Maps of the location of the JFAST drill site C0019 off of the eastern coast of northern Japan and in the 

vicinity of the 2011 Tohoku earthquake rupture area. Filled red circles indicate ocean drilling sites, filled red star is 

the epicenter of the Tohoku earthquake, and the red lines show the location of key geophysical surveys. a) The drill 

site C0019 is located at the inner slope of the Japan Trench. Contours show a schematic representation of the 

coseismic slip inferred from various data sets. Dashed line shows the approximate rupture area of the 1896 MeijiSanriku tsunami earthquake. b) Detail map shows the proximity of site C0019 to the repeat seismic and swathbathymetry surveys that document large slip occurred up to the axis of the trench. Line HD33B shows the location 

of the in-line seismic profile through the drill site.

10
 Drilling the plate boundary interface was technically challenging because of the 6.9 km water 

depth and the need to penetrate > 800 m through the prism to reach the subducting plate. 

Nonetheless, three successful holes were drilled to the target depth at Site C0019 (Figure 1), and 

borehole and core data define the location and structure of the plate-boundary décollement 

within the area that displayed large, shallow slip during the Tohoku-Oki event. Data from the 

logging-while-drilling and coring boreholes completed during the first leg of the expedition 

(343) indicate that the location of the décollement is tens of meters above bedded chert and 

basalt of the subducting plate and, similar to other subduction thrusts, may be controlled by the 

lithostratigraphy of the incoming plate. Interpretations of a seismic lines through the drill site 

suggest a total displacement of more than 3 km has occurred on the décollement at the borehole. 

Notably, coring shows the décollement zone is less than 5 m thick, which is considerably thinner 

than subduction thrusts drilled elsewhere. Distinguishing characteristics of the décollement that 

could favor coseismic weakening mechanisms include the pronounced localization of shear to a 

meters-thick layer of scaly clay, mesoscale slip surfaces within the layer, and narrow zones of 

fault-related damage in sediment bounding the layer. A one meter section of the scaly clay was 

retrieved, which provides ample material for characterization of structural, physical, chemical 

and mechanical properties of the plate interface, and post-cruise analyses of samples are already 

producing new results. The third hole was completed during the second leg of the expedition 

(343T), and a temperature measurement string was successfully installed across the plate 

boundary to quantify heat generated in this shallow region of the fault zone and allow 

determination of the fault shear strength during the earthquake. The décollement is not only the 

likely site of recent seismic slip, but also a type example of the shallow rupture zones that 

produce tsunami earthquakes along the Japan Trench. 

*Expedition 343 and 343T Scientists: 

Louise Anderson, University of Leicester, UK

Jan Behrmann, GEOMAR, Germany

Santanu Bose, University of Calcutta, India

Marianne Conin, CEREGE, France

Becky Cook, University of Southampton, UK

Patrick Fulton, University of Texas Austin, USA

Takehiro Hirose, KOCHI / JAMSTEC, Japan

Matt Ikari, MARUM / Univ. of Bremen, Germany

Tsuyoshi Ishikawa, KOCHI / JAMSTEC, Japan

Tamara Jeppson, Univ. of Wisconsin-Madison, USA

Jun Kameda, The University of Tokyo, Japan

James Kirkpatrick, Univ. California, Santa Cruz, USA

Weiren Lin, KOCHI / JAMSTEC, Japan

Toshiaki Mishima, Osaka City University, Japan

Casey Moore, Univ. of California, Santa Cruz, USA

Yasuyuki Nakamura, IFREE / JAMSTEC, Japan

Christine Regalla, Penn State University, USA

Francesca Remitti, Univ. Modena e Reggio Emilia, Italy

Christie Rowe, McGill University, Canada

James Sample, Northern Arisona University, USA

Tianhaozhe Sun, University of Victoria, Canada

Ken Takai, Biogeos / JAMSTEC, Japan

Yang Tao, China Earthquake Administration, China

Virginia Toy, University of Otago, New Zealand

Kohtaro Ujiie, University of Tsukuba, Japan

Monica Wolfson, University of New Hampshire, USA

Lena Maeda, CDEX / JAMSTEC, Japan

Sanny Saito, IFREE / JAMSTEC, Japan

Yoshinori Sanada, CDEX / JAMSTEC, Japan

Yukari Kido, CDEX / JAMSTEC, Japan

11
Coseismic fault rupture reaching the trench axis 

during the 2011 Tohoku-Oki earthquake 

Toshiya Fujiwara1, Shuichi Kodaira2, Tetsuo No2, and Yasuyuki Nakamura2

1

Institute for Research on Earth Evolution (IFREE), Japan Agency for Marine-Earth Science and 

Technology (JAMSTEC), Natsushima-cho 2-15, Yokosuka 237-0061, Japan. 

2

IFREE, JAMSTEC, Showa-machi 3173-25, Kanazawa-ku, Yokohama 236-0001, Japan. 

toshi@jamstec.go.jp 

Fault rupture during the 2011 Tohoku-Oki earthquake (MW 9.0), which generated huge 

tsunamis, is thought to have propagated to a shallow part of the subduction zone. This 

observation calls into question conceptual models that assume that the shallow part of the plate 

boundary interface in a seismogenic subduction zone slips aseismically. However, the available

observations of the earthquake and tsunami do not have sufficient resolution near to the 

subduction trench to determine whether coseismic fault slip extended all the way to the trench 

axis. Here we use bathymetric and seismic reflection data to image the seawards of the 

Tohoku-Oki earthquake epicentre, off the coast of Miyagi in the Tohoku district. 

We compared bathymetric profiles taken in 1999 and 2004 with one acquired along the same 

profile 11 days after the earthquake. The relative differences among these bathymetric data are 

minimal on the seaward side of the trench despite potential errors of several meters in vertical 

displacement and ~20 m in horizontal displacement. There were, however, large relative 

differences landward extended up to the trench axis, suggesting the earthquake fault rupture 

reached the trench axis. Comparison of the bathymetry before and after the earthquake shows a 

sharp contrast in seafloor elevation at the trench axis, and the seafloor is shallower throughout the 

landward side. 

Notably, on the outermost landward slope, the 40 km wide area between the slope break and 

the trench axis, the observed large seafloor elevation change corresponds to a sum of vertical 

displacement and additional uplift for the sloping seafloor due to horizontal displacement. We 

estimated the horizontal displacement by calculating the offset distance to maximize the 

cross-correlation of bathymetry. The estimated displacement is 56 m relative to the 1999 data, 

and 50 m relative to the 2004 data, toward the east-southeast. After restoring the horizontal 

displacement, the average elevation change became 10±7 m in comparison between the 1999 and 

2011 data (7±7 m between 2004 and 2011). We interpret these to represent vertical displacement, 

from the fault motion along the subducting plate and uplift from other unknown processes such 

as inelastic deformation. Overall, the seafloor on the outermost landward slope moved ~50 m in 

the east-southeast toward the trench and ~7-10 m upward between 1999 and 2011. Furthermore, 

12
upward and downward changes in seafloor elevation of ±50 m are evident at the axial seafloor. 

We also compared an image of a seismic profile taken in 1999 with one acquired in 2011. 

Subsurface of the landward slope, above the subducting oceanic crust, is characterized by a 

highly reflective zone. The highly reflective zone, which is about 2 km thick and seems to thin 

towards the land, consists of a series of reflectors that are subparallel to the subducting oceanic 

basement. Before the earthquake, we observed a triangular wedge of sediments at the trench axis. 

After the earthquake, we observed a deformed upheaval structure in the sedimentary layer that 

was 3 km long and 350 m thick. This structure is interpreted as compressional (that is, a thrust-up 

structure) with reverse faults branching from an interface in the subducting sedimentary layer, 

which is interpreted as the coseismic master fault. The seismic image beneath the landward slope 

of the trench axis, where 50 m of subsidence was observed in the differential bathymetric data, 

was imaged after the earthquake as a seismically scattered structure. This structure is interpreted 

to have formed by slumping. As the overriding block extended over the edge of the horst on the 

seaward slope, the ~50 m of horizontal movement of the block towards the trench brought the 

sedimentary block at the edge of the horst over the graben, which may have caused gravitational 

instability, triggering slumping on the seaward slope. 

Our examination of the observed structure leads us to propose the following scenario for the 

rupture propagation to the trench. Coseismic slip of the Tohoku-Oki earthquake starting from the 

epicentre at around 20 km depth propagated up-dip along the reflective zone. The slip continued 

to propagate along the interface beneath the frontal prism and slightly above the oceanic crust. 

The slip did reach and finally broke the sea floor at the trench axis. We conclude that the shallow 

plate interface at the subduction trench axis can slip seismically. 

13
The 2011 Tohoku-Oki earthquake and the Advanced Rapid Imaging and Analysis 

(ARIA) Project for Natural Hazard Monitoring and Response 

Mark Simons1, Sarah Minson2, Susan Owen3, Francisco Ortega1, Frank Webb3, Paul Rosen3, Jennifer Cruz3, 

Sang-Ho Yun3, Eric Fielding3, Angelyn Moore3, Hook Hua3, Paul Lundgren3 and Piyush Agram1

1 Seismological Laboratory, Division of Geological and Planetary Sciences, California Institute of Technology, 

Pasadena CA 91125 

2 United States Geological Survey, Department of Earth and Space Sciences, University of Washington, Seattle WA 

98195

3 Jet Propulsion Laboratory, California Institute of Technology, Pasadena CA 91109 

The 2011 Tohoku-Oki earthquake represents a watershed moment in both our 

understanding of giant megathrust earthquakes and the approaches used to describe, 

assess, and respond to such devastating events. The relatively unexpected nature of this 

event motivates the need for geophysicists to spend more time describing the inherent 

ambiguities of their models, in essence quantifying both what is known and what is not 

known. From the perspective of rapid assessment and response, this event also prompts 

us to consider different ways in which our geophysical tools and models can be exploited to 

fully benefit society. 

In the specific case of estimating fault slip during the different phases of the seismic cycle, 

we must try to (1) limit the use of a priori regularization, (2) understand the impact of both 

errors in our observations and inadequacies of our models, and (3) look for ways to 

describe the limited resolution of our inferred models. We will briefly outline how we are 

addressing these issues using a fully Bayesian methodology. While the computational 

challenges of this approach require both algorithmic advances and large computer 

resources, they allow us to hone our understanding of the extent to which our observations 

place constraints on the mechanical character of large faults. 

In order to enable the next leap in event assessment and response, we have initiated the 

Advanced Rapid Imaging and Analysis (ARIA) project - an effort to automate geodetic 

imaging capabilities for hazard response and societal benefit. Over the past decade, spacegeodesy (e.g., InSAR and GPS) has provided new assessment capabilities and situational 

awareness on the size, location, and character of earthquakes as well as on volcanic 

eruptions following magmatic events. Geodetic imaging’s unique ability to capture surface 

deformation with high spatial and temporal resolution allow us to resolve the properties of 

the earthquake in correspondingly high spatial and temporal detail. In addition, remote 

sensing with radar provides change detection and damage assessment capabilities for 

earthquakes, floods and other disasters that can image even at night or through clouds. 

However, since these data sets are still essentially hand-crafted, they are not generated 

rapidly and reliably enough to be useful for informing decision-making agencies and the 

public following an earthquake. The ARIA project is building an end-to-end prototype 

geodetic imaging system as the foundation for an operational hazard response facility 

integrating InSAR, GPS, seismology and modeling to deliver monitoring, actionable science 

14
and situational awareness products. For the 2011 Tohoku-Oki earthquake, the ARIA 

project provided processed GPS time series to the international community within days of 

the event allowing any interested group to model the data. This availability of this derived 

data product provided the foundation for a community assessment of what had just 

occurred. This effort was only possible due to GEONET’s laudable open data policy. 

We describe examples of the ARIA project data products for the 2011 Tohoku-Oki and the 

M6.3 Christchurch earthquakes. ARIA is now collaborating with USGS scientists in both the 

earthquake and volcano science program for our initial data product infusion. Perhaps the 

greatest hurdle for this endeavor is the free, open, and low latency access to relevant data 

streams for events distributed around the globe. Such access is critical to both advance our 

science and serve societal needs. 

15
The 2011 Tohoku-oki Earthquake 

related to a strong velocity gradient within the Pacific plate 

Makoto Matsubara1 and Kazushige Obara2

1National Research Institute for Earth Science and Disaster Prevention (NIED, Japan) 

2

Earthquake Research Institute, the University of Tokyo 

mkmatsu@bosai.go.jp 

We conduct seismic tomography using arrival time data picked by NIED Hi-net, including 

earthquakes off the coast, outside the seismic network around the source region of the 2011 

Tohoku-oki Earthquake. For these offshore events, we use the centroid depth estimated from 

moment tensor inversion by NIED F-net. After the Tohoku-oki Earthquake we also used the 

centroid depth estimated from seismograms of high-sensitivity accelerometers operated by NIED 

with moment tensor inversion (Asano et al., 2011). 

The target region, 20-48°N and 120-148°E, covers the Japanese Islands from Hokkaido to 

Okinawa. A total of manually picked 4,622,346 P-wave and 3,062,846 S-wave arrival times for 

100,733 earthquakes recorded at 1,212 stations from October 2000 to August 2009 is available 

for use in the tomographic method. In the final iteration, we estimate the P-wave slowness at 

458,234 nodes and the S-wave slowness at 347,037 nodes. The inversion reduces the root mean 

square of the P-wave traveltime residual from 0.455 s to 0.187 s and that of the S-wave data from 

0.692 s to 0.228 s after eight iterations (Matsubara and 

Obara, 2011). After the Tohoku-oki earthquake, we also 

used arrival time data from many aftershocks determined 

by moment tensor inversion (Asano et al., 2011) composed 

of 1,089,228 P- and 593,191 S-wave arrival times from 

4,384 events outside of the seismic network. 

Centroid depths are determined using a Green’s 

function approach (Okada et al., 2004) such as in NIED 

F-net. For the events distant from the seismic network, the 

centroid depth is more reliable than that determined by 

NIED Hi-net, since there are no stations above the 

hypocenter. 

We determine the upper boundary of the Pacific plate 

based on the velocity structure and earthquake hypocentral 

distribution (Fig. 1). The upper boundary of the low-V 

oceanic crust corresponds to the plate boundary where 

thrust earthquakes are expected to occur. Where we do not 

observe low-V oceanic crust, we determine the upper 

boundary of the upper layer of the double seismic zone 

within high-V Pacific plate. We assume the depth at the 

Japan trench as 7 km. 

150 100 50

Fig. 1 Depth contour of the upper 

boundary of the subducting Pacific plate

16
We can investigate the velocity structure within the Pacific plate such as 10 km beneath the 

plate boundary. The landward low-V zone with a large anomaly corresponds to the western edge 

of the coseismic slip zone of the 2011 Tohoku-oki earthquake estimated with waveform analysis 

(e.g. Suzuki et al., 2011; Yagi and Fukahata, 2011). The initial break point (hypocenter) is 

associated with the edge of a slightly low-V and low-Vp/Vs zone corresponding to the boundary 

of the low- and high-V zone. The trenchward low-V and low-Vp/Vs zone extending 

southwestward from the hypocenter may indicate the existence of a subducted seamount. The 

high-V zone and low-Vp/Vs zone might have accumulated the strain and resulted in the huge 

coseismic slip zone of the 2011 Tohoku earthquake. The low-V and low-Vp/Vs zone is a slight 

fluctuation within the high-V zone and might have acted as the initial break point of the 2011 

Tohoku earthquake. 

Reference: 

Asano, Y. et al.: Spatial distribution and focal mechanisms of aftershocks of the 2011 off the Pacific coast of Tohoku Earthquake, 

Earth Planets Space, 63, 675-679, 2011. 

Matsubara M. and K. Obara : The 2011 off the Pacific coast of Tohoku Earthquake related to a strong velocity gradient with the 

Pacific plate, Earth Planets Space, 63, 663-667, 2011. 

Okada Y. et al. : Recent progress of seismic observation networks in Japan -Hi-net, F-net, K-NET and KiK-net -,Earth, Planets 

and Space, 56, xv-xviii, 2004. 

Suzuki, W. et al.: Rupture process of the 2011 Tohoku-Oki mega-thrust earthquake (M9.0) inverted from strong-motion data. 

Geophysical Research Letters, 38, L00G16, doi:10.1029/2011GL049136, 2011. 

(a) (b)

Figure 2 P-wave velocity perturbation within the Pacific plate 10 km below the boundary (Matsubara 

and Obara, 2011) and the coseismic slip region of the Tohoku-oki earthquake. Coseismic slip is 

estimated by (a) Suzuki et al. (2011) and (b) Yagi and Fukahata (2011).

17
Yagi, Y.,and Y. Fukahata, Rupture process of the 2011 Tohoku‐oki earthquake and absolute elastic strain release, Geophys. Res. 

Lett., 38, L19307, doi:10.1029/2011GL048701, 2011.

18
Dynamic Wedge Failure Reveals Anomalous Characteristics of Shallow Subduction 

Earthquakes 

Shuo Ma (sma@mail.sdsu.edu) 

Department of Geological Sciences, San Diego State University, San Diego, CA 92182 

The deficiency of high-frequency seismic radiation from shallow subduction zone 

earthquakes was first recognized in tsunami earthquakes (Kanamori, 1972), which 

produce larger tsunamis than expected from short-period (20 s) surface wave excitation. 

Shallow subduction zone earthquakes were also observed to have unusually low momentscaled radiated energy compared to regular subduction zone earthquakes (e.g., Newman 

and Okal, 1998; Venkataraman and Kanamori, 2004; Lay et al., 2012). What causes this 

anomalous radiation and how it relates to large tsunami generation has remained unclear. 

Here we show that these anomalous observations can be due to extensive poroplastic 

deformation in the overriding wedge, which provides a unifying interpretation. 

Ma (2012) showed that the pore pressure increase in the wedge due to up-dip rupture 

propagation significantly weakens the wedge, leading to widespread Coulomb failure in 

the wedge. Widespread failure gives rise to slow rupture velocity and large seafloor uplift 

(landward from the trench) in the case of a shallow fault dip. Here we extend this work 

and demonstrate that the large seafloor uplift due to the poroplastic deformation 

significantly dilates the fault behind the rupture front, which reduces the normal stress on 

the fault and increases the stress drop, slip, and rupture duration. The spectral amplitudes 

of the moment-rate time function is significantly less at high frequencies than those from 

elastic simulations. Large tsunami generation and deficiency of high-frequency radiation 

are thus two consistent manifestations of the same mechanism (dynamic wedge failure). 

Although extensive poroplastic deformation in the wedge represents a significant portion 

of total seismic moment release, the plastic deformation acts as a large energy sink, 

absorbing nearly 50% of the total radiated energy from the fault, which leaves much less 

energy to be radiated and leads to low moment-scaled radiated energy as observed for 

shallow subduction zone earthquakes. 

Reference: 

Ma, S. (2012), A self-consistent mechanism for slow dynamic deformation and tsunami 

generation for earthquakes in the shallow subduction zone, Geophys. Res. Lett., 39, 

L11310, doi:10.1029/2012GL051854. 

19
20
Stress states before and after the 2011 Great Tohoku earthquake 

in and around the focal region 

Kuwahara, Y and K. Imanishi 

Geological Survey of Japan, AIST 

y-kuwahara@aist.go.jp

 The Mw9.0 Tohoku earthquake causes large changes in seismicity in and around the focal 

region, suggesting large crustal stress changes in these areas. This change can be 

qualitatively explained by large slip on a broad fault area of the main shock along the 

subducting plate interface. Several attempts in research papers quantitatively described 

how the seismicity changed and suggested the causes of changes, for instance, DCFF 

calculations etc. Among a lot of regions with large change in seismicity, a normal fault 

stress regime (NFSR) after the main shock are limited in two inland regions and in the 

large area of the main shock focal region, where the preshock stress states were 

considered to be a reverse fault stress regime (RFSR). One of the two inland areas is 

Iwaki region where an M j 7.0 normal fault earthquake occurred a month after the main 

shock. While the deviatoric stress change caused by the main shock is calculated at a few 

tens MPa in the source region and a few MPa in the inland area at most. This suggests a 

Fig.1 Focal mechanism solutions and epicenter distributions. (a) January 1, 2000

–March 10, 2011 before the 20011 Tohoku earthquake. (b) March 11–December 31, 

2011 after the 2011 main earthquake. (From Imanishi et al.(2012))

21
few candidates of reasons why the normal fault earthquake occurred: one is that the 

fracture strength of normal faulting is especially small in these areas, or the other is that 

NFSR existed locally even before the main shock. 

 We, thus, examined closely the stress state before the main shock in those areas. The 

preshock stress in Iwaki region, where the focal mechanisms of earthquakes were rarely 

found in the JMA routine catalogue, was investigated by determining 26 focal 

mechanisms of microearthquake using absolute body wave amplitudes as well as P-wave 

polarities. The result shows that the preshock stress state in the Iwaki limited region is the 

NFSR in contrast to the overall RFSR in the wide area (Imanishi et al., 2012). 

 As for the main shock source region, Imanishi and Kuwahara (2012) examined the 

preshock stress field in the overriding plate by using the F-net moment tensor solutions. It 

is noted that we carefully deselected the earthquakes which occurred along the plated 

boundary, since they cause a bias in estimation of a stress tensor inversion. The result 

indicates that the stress fieldd in the northern part of the main shock source region is 

noticeably different from that in the southern part: the northern part is under the strike slip 

stress regime with the maximum compressional stress axis (MCSA) trending to the 

largest slip area in the main shock fault, while the southern part is under the NFSR with 

the MCSA trending perpendicular to the plate boundary. 

 Thus, the regions where the normal fault earthquakes occurring after the main shock 

were found to be under the NFSR even before the 2011 main shock at least in the Iwaki 

region and in the southern part of the main shock source region. 

References 

Imanishi and Kuwahara (2012), Proper estimation of stress fields in the source region of 

the 2011 Off the Pacific Coast of Tohoku earthquake, JPGU meeting 2012. 

Imanishi, K., R. Ando and Y. Kuwahara (2012), Unusual shallow normal-faulting 

earthquake sequence in compressional northeast Japan activated after the 2011 off the 

Pacific coast of Tohoku earthquake, GRL, L09306, doi:10.1029/2012GL051491. 

22
Geodetic imaging of coseismic slip and postseismic afterslip: Sparsity promoting 

methods applied to the great Tohoku earthquake 

Eileen L. Evans and Brendan J. Meade 

Department of Earth & Planetary Sciences, Harvard University, Cambridge, MA, USA 

Geodetic observations of surface displacements during and following earthquakes such as 

the March 11, 2011 great Tohoku earthquake can be used to constrain the spatial extent 

of coseismic slip and postseismic afterslip, and characterize the spectrum of earthquake 

cycle behaviors. Slip models are often regularized by assuming that slip on the fault 

varies smoothly in space, which may result in the artificial smearing of fault slip beyond 

physical boundaries. Alternatively, it may be desirable to estimate a slip distribution that 

is spatially compact and varies sharply. Here we show that sparsity promoting state 

vector regularization methods can be used to recover slip distributions with sharp 

boundaries, representing an alternative end-member result to very smooth slip 

distributions. Using onshore GPS observations at 298 stations during and in the ~2 weeks 

following the Tohoku earthquake, we estimate a band of coseismic slip between 30 and 

50 km depth extending 500 km along strike with a maximum slip of 64 m, corresponding 

to a minimum magnitude estimate of MW=8.8. Our estimate of afterslip is located almost 

exclusively down-dip of the coseismic rup- ture, with a transition between 40 and 50 km 

depth and an equivalent moment magnitude MW=8.2. This depth may be interpreted as 

coincident with the transition from velocity strengthening to velocity weakening 

frictional behavior, con- sistent with the upper limit of cold subduction estimates of the 

thermal structure of the Japan trench. 

23
GSI activities in response to 

the 2011 off the Pacific coast of Tohoku Earthquake. 

Takashi SAITO, Toru NAGAYAMA, Kazuo INABA, Tamotsu HAYASHI 

 and Hiroyuki NAKAI 

Geospatial Information Authority of Japan (GSI) 

takasi-s@gsi.go.jp 

Geospatial Information Authority of Japan (GSI) is the national mapping organization in the 

Japanese Government. With 700 staff members in geospatial field, the organization conducted 

various kinds of activities in response to the 2011 off the Pacific coast of Tohoku Earthquake. This 

paper summarizes its activities as well as achievements and challenges recognized. 

Since the day of the occurrence of the earthquake, 11 March 2011, GSI has concentrated into 

disaster response activities. The major activity areas were: detection and analysis of crustal 

movements using GEONET (GNSS Earth Observation Network System operated by GSI) and 

In-SAR for understanding the earthquake; aerial photo survey and tsunami inundation mapping for 

recognition of the damage by the main shock and the following tsunami; revision of the result of 

control points and provision of base maps for reconstruction support and monitoring of postseismic 

deformation by GEONET. 

Figure 1 shows the crustal movement caused by the earthquake. 

Figure 1. Horizontal and vertical displacements by the earthquake. 

24
Because of large postseismic deformation, the ground surface in the Tohoku area is still 

moving 1-2 cm/month. 

Figure 2 is an example of orthophoto map produced by GSI. It shows the severe damage by the 

huge tsumani. 

Figure 2. An example of orthophoto map, Rikuzen takata City. 

Major achievements of GSI’s experience are; quick data gathering, development and provision; 

devising new arrangements for effective and efficient data delivery; and wider use of GSI’s 

products in the society, particularly rescue and recover organizations. 

Meanwhile the following challenges prompting further improvement are recognized: ensuring 

resiliency and redundancy of communication, energy and facilities; further rapid data 

development; data provision in appropriate methods satisfying diversified user needs. 

As occurrence of natural disasters never ends, geospatial engineers always need to learn about 

their experiences mutually and collectively for better responses. 

25
Session II 

Abstracts 

26
USGS Seismic Hazard Mapping Efforts: U.S. National Seismic Hazard Maps 

and Urban Seismic Hazard Maps Based on 3D Simulations 

Arthur D. Frankel 

U.S. Geological Survey 

Seattle, WA 

afrankel@usgs.gov

The U.S. Geological Survey produces probabilistic seismic hazard maps for the 

United States for a firm-rock site condition, as well as urban seismic hazard maps for 

selected cities that include detailed maps of site conditions. My presentation will describe 

the U.S. national seismic hazard maps and the urban seismic hazard maps for Seattle, 

WA that incorporate 3D sedimentary basin effects, non-linear site response, and rupture 

directivity. 

The U.S. national seismic hazard maps are based on geologic slip-rate and 

paleoseismic data on about 500 faults, historical and instrumental seismicity catalogs, 

crustal deformation measurements, and multiple ground-motion prediction equations 

(Frankel et al., 1996, 2002; Petersen et al., 2008). The hazard maps are constructed from 

the mean hazard curves derived from logic trees of alternative models of seismicity, 

magnitude-frequency distributions on faults, recurrence parameters, maximum 

magnitudes, ground-motion prediction equations, and other parameters. There is a wealth 

of associated products available from the website at eqhazmaps.usgs.gov, including 

hazard curves, uniform hazard spectra, deaggregation of hazard by magnitude, distance, 

and location, and earthquake probability maps. 

The U.S. national maps are the basis for seismic provisions in building codes used in 

all 50 states (International Building and Residential Codes) and are also applied in bridge 

design, landfill regulations, earthquake insurance premiums, emergency management, 

and many other applications. There is an extensive workshop and review process during 

each 6-year update of the national maps, involving hundreds of scientists. The maps are 

currently being updated for release in 2014. 

The hazard from M8-9 earthquakes on the Cascadia subduction zone (CSZ) has been 

included in the U.S. national maps since 1996. A 500 year average recurrence time for 

M9 earthquakes that rupture the entire CSZ was used, based on observations of coastal 

subsidence, tsunami deposits, and liquefaction over the past 5,000 years (e.g., Atwater 

and Hemphill-Haley, 1997; Kelsey et al. 2002; Nelson et al., 2006). The hazard from M8 

earthquakes that could rupture anywhere along the length of the CSZ was also included. 

Recently published work by Goldfinger et al. (2012) described their analysis of turbidites 

from deep-sea cores to reconstruct the history of M8-9 earthquakes in the CSZ over the 

past 10,000 years. This work indicates that there have been numerous M8 earthquakes 

that have only ruptured the southern portion of the CSZ, in addition to the M9 

earthquakes that likely ruptured the entire length of the CSZ. Onshore geologic 

observations also indicate that M8 earthquakes occurred along the southern portion of the 

CSZ (Nelson et al., 2006). There is also evidence from tsunami deposits that may indicate 

27
that M8 earthquakes can occur along the northern portion of the CSZ (Atwater and 

Griggs, 2012). We have developed a new logic tree for the recurrence parameters of 

Cascadia earthquakes incorporating these additional recurrence models, based on input 

from scientists during a workshop convened by the USGS (Frankel, 2011). Another key 

parameter to the hazard maps is the location of the down-dip edge of rupture for great 

CSZ earthquakes, since there is virtually no interface seismicity in most of the CSZ to 

constrain this location. In a second workshop that we convened, participants favored 

models for the rupture zone based on inversions of GPS and uplift data and the location 

of the up-dip edge of episodic tremor and slip events. We are also evaluating groundmotion prediction equations for great subduction-zone earthquakes to apply in the 2014 

update, by comparing predicted values with observations from the Tohoku, Japan and 

Maule, Chile earthquakes. 

We have also developed urban seismic hazard maps that include the effects of deep 

sedimentary basins and shallow soils. The Seattle urban seismic hazard maps are based 

on 541 three-dimensional simulations of earthquakes on the Seattle fault, Southern 

Whidbey Island fault (SWIF), the Cascadia subduction zone, and random shallow and 

deep sources (Frankel et al., 2007). The maps are for 1 Hz spectral acceleration and are 

based on the same earthquake recurrence probabilities used in the national maps. The 3D 

velocity model was validated by modeling waveforms and amplifications for several 

events including the M6.8 Nisqually earthquake. Observed waveforms in the Seattle 

Basin show substantial amplification caused by basin-edge focusing of S-waves and 

basin surface waves generated by conversion of S-waves at the edge of the basin. The 

amplification from these 3D basin effects would not be captured by modeling verticallypropagating S-waves. The Seattle maps also contain the non-linear amplification from the 

soft soils of fill and alluvium, using empirical factors based on the 30m averaged shearwave velocity. Rupture directivity was also included in the simulations for earthquakes 

on the Seattle fault and SWIF. The maps show highest hazard for sites on soft soils 

within the Seattle basin. Next highest hazard is for stiff-soil sites within the basin and 

soft-soil sites outside the basin. The overall amplification for sites in the Seattle basin 

portrayed in the hazard maps is similar to the observed amplification from the Nisqually 

earthquake. 

References

Atwater, B.F., and G.B. Griggs (2012). Deep-sea turbidites as guides to Holocene 

earthquake history at the Cascadia Subduction Zone—Alternative views for a 

seismic-hazard workshop: U.S. Geological Survey Open-File Report 2012–1043, 

58 p., available at http://pubs.usgs.gov/of/2012/1043/

Frankel, A., C. Mueller, T. Barnhard, D. Perkins, E. Leyendecker, N. Dickman, S. 

Hanson, and M. Hopper (1996), National seismic-hazard maps: documentation 

28
June 1996, U.S. Geological Survey, Open-file Report 96-532, 110 pp, on website 

http://eqhazmaps.usgs.gov

Frankel, A., M. Petersen, C. Mueller, K. Haller, R. Wheeler, E. Leyendecker, R. Wesson, 

S. Harmsen, C. Cramer, D. Perkins, and K. Rukstales (2002). Documentation for 

the 2002 update of the national seismic hazard maps, U.S. Geological Survey, 

Open-file Report 02-420, 39 pp, on website http://eqhazmaps.usgs.gov

Frankel, A. D., W. J. Stephenson, D. L. Carver, R. A. Williams, J. K. Odum, and S. Rhea 

(2007). Seismic hazard maps for Seattle incorporating 3D sedimentary basin 

effects, nonlinear site response, and rupture directivity, USGS Open-File Report 

07-1175, 70 pp., available at: http://pubs.usgs.gov/of/2007/1175/ 

Frankel, A.D. (2011). Summary of November 2010 meeting to evaluate turbidite data for 

constraining the recurrence parameters of great Cascadia earthquakes for the 

update of the national seismic hazard maps, U.S. Geologic Survey Open-File 

Report 2011–1310, 13 p., available at http://pubs.usgs.gov/of/2011/1310/. 

Goldfinger, C., C.H. Nelson, A. Morey, J.E. Johnson, J. Gutierrez-Pastor, A.T. Eriksson, 

E. Karabanov, J. Patton, E. Gracia, R. Enkin, A. Dallimore, G. Dunhill, and T. 

Vallier (2012). Turbidite Event History: Methods and Implications for Holocene 

Paleoseismicity of the Cascadia Subduction Zone, USGS Professional Paper 

1661-F, Reston, VA, U.S. Geological Survey, 332 pp, 64 Figures. 

Kelsey, H.M., R.C. Witter, and E. Hemphill-Haley (2002). Plate-boundary earthquakes 

and tsunamis of the past 5500 years, Sixes River estuary, southern Oregon.

Geological Society of America Bulletin v. 114, p. 298–314. 

Nelson, A.R., H.M. Kelsey, and R.C. Witter (2006). Great earthquakes of variable 

magnitude at the Cascadia subduction zone. Quaternary Research. v. 65, p. 354–

365. 

Petersen, M., Frankel, A., Harmsen, S., Mueller, C., Haller, K., Wheeler, R., Wesson, R., 

Zeng, Y., Boyd, O., Perkins, D., Luco, N., Field, E., Wills, C., and Rukstales, K. 

(2008). Documentation for the 2008 Update of the United States National Seismic 

Hazard Maps: U.S. Geological Survey Open-File Report 2008–1128, 61 pp., on 

website http://eqhazmaps.usgs.gov

29
National Policy and Project on the Earthquake Research after the 2011 Off the 

Pacific Coast of Tohoku Earthquake

Koshun Yamaoka 

Earthquake and Volcano Research Center, Nagoya University 

kyamaoka@seis.nagoya-u.ac.jp 

 The gigantic earthquake off the Pacific coast of Tohoku (M9.0) required Japan’s national 

policy and program on earthquake research a serious amendment especially on the tsunami 

disaster mitigation and evaluation of large interplate earthquakes along subduction zone. 

 Japan’s researches on earthquakes in national level have been promoted based on a policy 

and a program. The former is “Basic comprehensive policy for the promotion of earthquake 

observation, measurement, surveys and research (hereafter, we call it basic comprehensive 

policy)”, which is issued by the Headquarters of Earthquake Research Promotion (HERP). The 

latter is “National observation and research program for the prediction of earthquakes and 

volcanic eruptions (hereafter, we call it prediction program)”, which is issued by the Council for 

Science and Technology. Both are revised or being revised through intensive discussions. As the 

amendment of the prediction program is still under progress, here I report how the basic 

comprehensive policy is revised. 

 The main cause of the devastating disaster in the earthquake was the tsunami that exceeded 

the hazard assessment in the coastal area of Tohoku region. More than 19,000 people died 

because the height and inundation of the tsunami extremely exceeded what they have anticipated 

before. The lessons from the earthquake should be applied immediately to another gigantic 

earthquakes, among which large interplate earthquakes along Nankai Trough that may produce 

extremely large tsunami. The Central Disaster Management Council (CDMC) recently released 

the disaster assessment, in which the death toll will be 320,000 in the worst case. 

 The problems opposing the existing basic comprehensive polity are 1) evaluation of 

largest-class interplate earthquakes, 2) rapid estimation of magnitude more than 8 in the 

earthquake early warning (EEW) system, and 3) evaluation and early warning of tsunami 

hazards. 

 The HERP has been evaluated the probability of earthquakes based on the historical and 

geological records of past earthquakes. The temporal limitation of the availability of the record is 

the main reason for the failure in the estimation of larger but less frequent event such as the 2011 

Tohoku event. In the off the Pacific coast of Tohoku region the manner of earthquake occurrence 

is evaluated based on the well-studied records in the past 400 years. The recurrence interval of 

the 2011-type event, if exists, is estimated to be more than 500 years, and could not be properly 

30
evaluated only by the record of past earthquakes. The revised basic comprehensive policy states 

that the seafloor geodetic and seismic observations in addition to the geological survey on the 

past earthquakes are necessary to improve the reliability of long-term evaluation of earthquake 

occurrence. 

 The early information of earthquakes and tsunamis is also essential for rapid evacuation 

from large tsunamis. In addition to the difficulty to estimate the source region in real time, which 

has been pointed out, the present EEW system did not estimate the magnitude of the Off Pacific 

Coast of Tohoku Earthquake. The revised basic comprehensive policy states that seafloor 

observations in addition to the extensive use of land-based GPS network are necessary to 

improve the reliability of the EEW system. Real-time seafloor observation network, such as 

off-shore tsunami observation stations, should also be deployed for the real-time data utilization 

of tsunami, which will be used to improve the tsunami warning accuracy in combination with the 

development of rapid tsunami forecast method. 

 Tsunami hazard assessment has been made by CDMC and local governments based on the 

long-term evaluation of earthquakes by HERP. The reason why the tsunami hazard is 

underestimated in most of the Pacific coast of Tohoku is partly miscommunication among the 

organizations. The meaning of the long-term evaluation in the off the coast of the Tohoku region 

is not well informed. The revised basic comprehensive policy states that the HERP should 

provide appropriate methods of tsunami hazard assessment to the local governments for better 

tsunami disaster mitigation action. 

31
E-DECIDER: Experiences Developing Earthquake Disaster Decision 

Support and Response Tools 

Margaret Glasscoe, Andrea Donnellan, Timothy Stough, Jay Parker, Michael Burl, 

Robert Granat 

Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA

Marlon Pierce, Jun Wang, Yu Ma 

Indiana University, Bloomington, IN 

John Rundle, Mark Yoder 

University of California, Davis CA 

Gerald W. Bawden 

US Geological Survey, Sacramento, CA 

Seth Gorelik 

University of California, Santa Barbara CA 

Within days following the devastating Tohoku-oki event, the E-DECIDER team 

worked with USGS International Charter representatives to provide remote 

sensing products to the Japanese government so they could assess damage 

from the tsunami and earthquake. The team provided geo-referenced maps of 

target areas identified by the Japanese International Charter representative, 

showing before and after high resolution optical images, including those of the 

Fukushima nuclear reactor. We provided our first change detection results within 

a few days and our image pair maps within a week, alongside other teams 

working with the US International Charter representatives. 

Earthquake Data Enhanced Cyber-Infrastructure for Disaster Evaluation and 

Response (E-DECIDER) is a NASA-funded project developing new capabilities 

for decision-making, utilizing remote sensing data and modeling software, to 

provide decision support for earthquake disaster management and response. EDECIDER incorporates the earthquake forecasting methodology and geophysical 

modeling tools developed through NASAʼs QuakeSim project. 

Geodetic imaging data, including from inteferometric synthetic aperture radar 

(InSAR) and GPS, as well as other remotely sensed data, have proven to be 

useful in earthquake research. As more of these types of data have become 

increasingly available they have also shown great utility for providing key 

information for disaster response. 

Work has been done to translate these data into useful and actionable 

information for decision makers in the event of an earthquake disaster. In 

32
addition to observed data, modeling tools provide essential preliminary estimates, 

while data are still being collected and/or processed, which can be refined as 

data products become available. Now, with more data and better models, we are 

able to provide these to responders who need easy tools and routinely produced 

data products. These data products can be used to help focus response efforts 

in the wake of an earthquake disaster, as well as aid in long-term planning and 

mitigation.

Our experiences with the Japan earthquake, and other recent global earthquakes 

like the Haiti event, have highlighted which remote sensing products were most 

readily available in the aftermath of a large disaster. In most cases high 

resolution optical data was most rapidly and readily accessible, rather than radar 

or other sources. These events also revealed the lack of collaborative 

infrastructure and also demonstrated the lack of worldwide hazard modeling 

services. Other issues revealed included limited search capability of available 

data (and often limited access to data), no automated data quality filter (which 

hindered rapid analysis), distribution of data across multiple providers with no 

standard interface, no automated delivery system, and user-restricted data – 

which requires time to negotiate the restrictions and takes precious time when 

responding to a disaster. 

These lessons and experiences have helped us to evaluate the needs of endusers for decision support products and have driven the development of our 

capabilities for supporting disaster response in both California and other regions. 

33
Some considerations for improvement of the National Seismic Hazard Maps 

for Japan

Hiroyuki Fujiwara 

National Research Institute for Earth Science and Disaster Prevention, Japan 

fujiwara@bosai.go.jp 

The Tohoku-oki earthquake (Mw 9.0) of March 11, 2011, was the largest event in the history 

of Japan and was recorded by nearly 1200 K-NET/KiK-net stations with a peak ground 

accelerations of 2933 gals and more than 1g at 10 sites. This mega-thrust earthquake was not 

considered in the national seismic hazard maps for Japan that were published by the headquarters 

for earthquake research promotion of Japan. By comparing results of the seismic hazard 

assessment and observed strong ground motions, we understand that the results of assessment 

were underestimated in Fukushima prefecture and northern part of Ibaraki prefecture. Its cause 

primarily lies in that it failed to evaluate the M9.0 mega-thrust earthquake in the long-term 

evaluation for seismic activities. On the other hand, another cause is that we could not have 

established the functional framework which is prepared for treatment of uncertainty for 

probabilistic seismic hazard assessment. We consider problems and issues to be resolved for 

probabilistic seismic hazard assessment based on the lessons learned from this earthquake 

disaster and make new proposals to improve probabilistic seismic hazard assessment for Japan. 

We have made a revision of the seismic hazard assessment based on the revised version of the 

"Long-term evaluation of seismic activity for the region from the off Sanriku to the off Boso" by 

the ERCJ. Revision of seismic activity model for other regions of Japan has been undergoing. 

After the revision of long-term evaluation for whole of Japan, we will recalculate seismic hazard. 

The followings are problems to be solved in the future. 

(1) Modeling of seismic activity with no oversight to low-probability earthquakes 

For both subduction zone earthquakes and earthquakes at active faults, it is necessary to aim 

to model seismic activity that can be considered to events about once several thousands or several 

tens thousands of years. To achieve this goal, we need to model background earthquakes that 

include a low probability of earthquakes by using the Gutenberg-Richter formula or other 

statistical techniques to compensate the long-term evaluation. 

(2) Preparation of strong ground motion maps considering low-probability earthquakes 

In addition to emphasize the urgency of the earthquake occurrence by showing the probability, 

by going back to the original purpose of the evaluation of probabilistic seismic hazard, we should 

prepare the maps that show the strong-motion level for earthquake preparedness. For example, 

based on the averaged long-term seismic hazard assessment, evaluating strong-motion level for 

34
about 10,000-100,000 years return period, we should prepare the maps that show the distribution 

of strong-motion level. Regarding the seismic hazard assessment for low probability, at present, it 

is insufficient to evaluate the uncertainty of ground motion prediction for low probability M8 

class earthquakes and it is necessary to improve techniques for them. 

(3) Development of methodology for selecting appropriate scenario earthquakes from 

probabilistic seismic activity model 

In the seismic activity model considering low-probability earthquakes, not only earthquakes 

with specified faults, but also earthquakes without specified faults are included. From the seismic 

activity model, it is necessary to establish a methodology that can be selected as appropriate 

scenario earthquakes for purposes of earthquake preparedness. 

(4) Development of methodology for prediction of strong ground motions for mega 

earthquakes 

In order to perform seismic hazard assessment considered the low-probability events, it is 

necessary to predict strong ground motions for large earthquakes that have not been recorded by 

the modern seismic observation network. For the "Method for prediction of strong ground motion 

for earthquakes with specified faults (recipe)", which is currently being used for strong motion 

prediction, the subduction zone earthquakes up to about M8 and earthquakes on active fault up to 

about 80km in length are only verified its scope. The sophistication of techniques that can be 

applied to the prediction of strong ground motions for super large earthquakes are required. 

 

Figure 1. Maps for distribution of seismic intensity corresponding to (a) return period of 1,000 

year and (b) that of 100,000 year. 

JMA seismic intensity JMA seismic intensity

(a)

 

(b)

 

35
Time-independent earthquake forecasts for the Intermountain West, United States 

Morgan Moschetti, U.S. Geological Survey, Golden, CO, mmoschetti@usgs.gov

We generate a high resolution, time-independent earthquake forecast for the 

Intermountain West (IMW), United States by spatially smoothing the seismicity 

rates of M4+ earthquake epicenters. We calculate information gain parameters to 

determine the smoothing method that best predicts the spatial distribution of 

seismicity rates from an independent sub-catalog. Models are generated from a 

declustered earthquake catalog with magnitude completeness levels at M4, M5 and 

M6. The forecast assumes that the Gutenberg-Richter relation describes the 

magnitude-frequency distribution and that the locations of smaller earthquakes 

(M4+) can identify the locations of future large, and damaging, earthquakes. 

Spatially smoothed seismicity rate models are generated with isotropic and 

anisotropic smoothing kernels, using Gaussian and power-law functions with fixed 

and adaptive bandwidths. We implement the adaptive smoothing method of 

Helmstetter et al. (2007), which varies smoothing bandwidth based on the local 

seismicity density, for isotropic smoothing and modify the method for anisotropic 

smoothing kernels. To identify an optimal smoothing method for long-term 

earthquake forecasting, we divide the IMW earthquake catalog, by date, into two 

independent sub-catalogs. Smoothing methods are applied to the earlier catalog to 

generate forecast models, which are then compared with the later catalog. We 

calculate likelihood values for all smoothed seismicity models, by assuming a 

Poisson distribution for earthquake occurrence, and select the smoothed seismicity 

model that maximizes an information gain parameter. For the isotropic models, 

adaptive smoothing methods with Gaussian kernels provide the highest information 

gain values and are used to generate the final time-independent earthquake forecast 

for the IMW. We also investigate the use of different magnitude thresholds for the 

36
smoothed seismicity models and find that the incorporation of smaller earthquakes 

(M4+) improves the forecast of M5+ earthquakes compared to the use of only larger 

magnitude (M5+) earthquakes. 

37
Session III

Abstracts 

38
Assessing Tsunami Hazard from Paleotsunami Deposits 

Bruce Jaffe, US Geological Survey, USA 

Kazuhisa Goto, International Research Institute of Disaster Science (IRIDeS), 

Tohoku University, Japan 

The 11 March 2011 Tohoku-Oki tsunami dramatically demonstrated the vulnerability of 

the world’s coastlines to the impact of tsunamis. Although northeast Japan had 

experienced large tsunamis in the past, there was no historical precedent for the March 11

tsunami. Many areas of the world capable of receiving such catastrophic tsunamis have 

not experienced them during the short period of written history. Sedimentary deposits left 

by tsunamis are being used to extend the record of tsunamis back through time. The state 

of the science for tsunami deposits has now evolved to a point where false positives (e.g. 

misinterpreting a storm deposit as a tsunami deposit) are less frequent. Tsunami hazard 

assessment is beginning to incorporate the spatial distribution of tsunami deposits and the 

record of tsunami recurrence. 

A recent development in the use of tsunami deposits for tsunami risk assessment is to 

obtain tsunami magnitude estimates by applying sediment transport models to replicate 

the observed deposits. Models have focused on estimating two parameters, tsunami 

height and flow speed. These models are developed and tested using data sets collected 

from recent tsunamis (Papua New Guinea 1998, Peru 2001, Indian Ocean 2004, Samoa 

2009, Chile 2010, and most recently, Tohoku-Oki 2011). One fundamental question is 

whether tsunamis leave a deposit to the limit of inundation. Field data collected from 

1998 to 2010 showed that the extent of tsunami deposits were less than the maximum 

inundation, but typically were within 10% on gently sloping coastal plains. However, 

recent field investigations on the coastal plain of Sendai, Japan after the 2011 tsunami 

bring into question whether the extent of deposits for extremely large tsunamis are a good 

proxy for maximum inundation distance. There, because of sediment source limitations, 

an easily recognizable deposit (sand thickness >0.5 cm) only extended about 2/3 of the 

way to the limit of inundation. This new data highlights the need to incorporate other 

proxies such as geochemical signatures and approaches such as sediment transport 

modeling in tsunami hazard assessment. 

39
Strategy for evaluating giant earthquake and tsunami by coastal 

paleoseismology

Masanobu Shishikura 

Active Fault and Earthquake Research Center, Geological Survey of Japan/AIST 

m.shishikura@aist.go.jp 

The Great Off-Tohoku Earthquake (M 9.0) of 2011 turned out to be an unprecedented 

disaster due to the giant tsunami that invaded the Pacific coast, and it is often said that its 

magnitude was “unexpected.” However, geological data such as tsunami deposit obtained from 

the coast facing the Japan Trench suggested that the giant tsunami as large as the 2011 event had 

repeatedly occurred for several thousand years, including the Jogan Earthquake (greater than M 

8.4) of 869. Subduction Zone Earthquake Research Team in GSJ has conducted 

paleoseismological survey to evaluate the recurrence time, tsunami inundation area and source of 

the Jogan Earthquake and its predecessors since 2004. Eventually, the inundation area of the 

tsunami in 2011 was very similar to the estimated tsunami inundation area of the Sendai Plain at 

the time of the Jogan Earthquake (Fig. 1). What this implies is that if the magnitudes of past 

earthquakes and tsunamis are elucidated and if histories of occurrence are reconstructed, we will 

be able to make a rough assumption of the magnitude and imminence of future probable 

earthquakes and tsunamis. 

Figure 1. Comparison of spatial distributions of 

the present tsunami inundation (Right figure) with 

old tsunami deposits brought by the AD 869 Jogan 

earthquake (Left figure). The right figure is from a 

WEB site of Geospatial Information Authority of 

Japan. Color contours in the left figure shows 

maximum flow depth computed for the AD 869 

Jogan earthquake source model.

40
Figure 2. Tsunami boulders in the Shionomisaki Cape

After the 2011 earthquake, GSJ urgently surveyed to observe the distribution and 

sedimentological characters of tsunami deposit which was derived from the 2011 tsunami. This is 

for improving a reconstruction technique of past tsunami inundation. From the results of this 

survey, it is recognized that actual tsunami inundation is able to reach 1-2 km further inland than 

the landward limit of the distribution of tsunami deposit. For more reliable estimation of future 

tsunami inundation area, it is highly important that we not only focus on the distribution of past 

tsunami sand layer, but also evaluate the scale of tsunami inundation by methods such as 

chemical component analysis in combinating with tsunami simulations. This instruction should 

be immediately apply to other coastal areas facing subduction zone which have potential of giant 

tsunami in near future such as the Nankai Trough. GSJ therefore is conducting field survey along 

the Pacific coast of Japan. 

On the other hand, regardless of paleoseismology, recently the government announced the 

estimation of disaster for future giant earthquake and tsunami in the worst case simulated from 

the largest source. However the evidence of such largest event has not yet been found in any 

records not only historically but also geologically. Therefore a role of paleoseismological study 

was oppositely changed. Before the 2011 event, paleoseismologists suggested the possibility of 

future giant earthquake from field survey data by inductive approach. But after the 2011 event, 

paleoseismologists must evaluate by deductive approach whether such the largest event suggested 

by the government exist or not from the evidence of field survey data. 

One of the solutions to evaluate the largest event was identified in the Shionomisaki Cape, 

where we found tsunami boulders which were moved at only the timing of giant earthquake 

generated from the Nankai Trough such 

as the 1707 Hoei earthquake (M 8.6) 

(Fig. 2). The boulders are distributed 

over the range of ca. 200 m from 

shoreline, but nothing was found on the 

Holocene terrace of 2-4 m in altitude 

just behind them. Because the terrace 

was probably emerged during 6000 

years ago, the largest tsunami in the 

past 6000 years must be not able to 

transport the boulders over the terrace. 

Then it can evaluate the actual 

magnitude of largest tsunami locally. 

41
JMA's response to the 2011 off the Pacific coast of Tohoku Earthquake 

and planned Improvements of Tsunami Warning

Takeshi Koizumi 

Earthquake and Tsunami Observations Division, Seismological and Volcanological Department, 

Japan Meteorological Agency 

t-koizumi@met.kishou.go.jp 

At 14:46 JST, March 11 2011, the 2011 off the Pacific coast of Tohoku Earthquake started its 

fault rupture from off coast of Miyagi Prefecture. The Japan Meteorological Agency (JMA) 

estimated its magnitude as 7.9 (Mj: JMA magnitude) in 3 minutes and disseminated the first 

tsunami warning at 14:49, in which estimated tsunami heights were stated as 6m for Miyagi Pref. 

and 3m for Iwate and Fukushima Pref. With near-shore GPS buoys as well as tide gauges along 

the coast, the JMA successively updated tsunami warning until 03:20 JST, March 12, when the 

whole Japanese coastlines were covered by warnings/advisories. 

The main issue of the JMA's tsunami warning for this event was the underestimated first 

warning based on the underestimated Mj7.9, and it might have resulted in the delay of evacuation. 

To deal with this problem, the JMA has been introducing tools with which validity of Mj 

estimation can be evaluated before the first tsunami warning. If the possibility of much larger 

magnitude than Mj is detected, the JMA will issue tsunami warning by replacing the Mj with the 

expected maximum magnitude in the region. In this case, as there is large uncertainty of tsunami 

height estimation, the JMA will not inform the estimated height numerically but qualitatively by 

an expression conveying emergency situation to the people. Also some changes in warning 

statements: tsunami height classification will be decreased from eight (0.5m, 1m, 2m, 3m, 4m, 

6m, 8m, >=10m) to five (1m, 3m, 5m, 10m, >10m) taking into account the realistic variety of 

countermeasures in time of emergency and forecast error range, for instance. 

In addition, some causes of the delay of tsunami warning update were pointed out. The JMA 

could not calculate Mw of the main shock within 15 minutes as with the JMA's normal operation 

because very large seismic waves went off the scale of most of the JMA's broadband 

seismographs (STS-2) in Japan. And data from offshore ocean-bottom pressure gauges could not 

be applied for tsunami warning update. In order to deal with these issues, the JMA will deploy 80 

new "broad-band strong motion" seismographs which ensure Mw within 15 minutes even in case 

of near-field huge earthquakes, and will promote the utilization of ocean-bottom pressure gauges 

including 3 DART buoys which will be installed by the JMA. 

The above described tsunami warning improvement measures will be put into operation by 

March 2013, subject to the system modification of both the JMA and organs responsible for 

42
transmitting and using tsunami warning. 

Possibility of 

magnitude 

underestimation

Eq.

Mw and CMT calculation

Updated warning

3 min.

15 min.

Quick hypocenter 

and magnitude(Mj) 

calculation

No Yes

First warning based on the

assumed maximum 

magnitude in the area

First warning 

based on Mj

Predicted tsunami height 

qualitatively

Predicted tsunami 

height in number

Offshore tsunami data 

analysis

Predicted tsunami height in number

Figure 1. Flowchart of planned improved tsunami warning procedure 

Category

Present Improvement Plan

Expression of

Tsunami height

Expression of

Tsunami height Predicted height

Numerical Qualitative

Tsunami

Warning

Major Tsunami

10m or more, 8m, 

6m, 4m, 3m

Over 10m

Huge

 10m -

10m 5m to 10m

5m 3m to 5m

Tsunami 2m, 1m 3m High 1m to 3m

Tsunami Advisory 0.5m 1m (Blank) 0.2m to 1m

Table 1. Categories and classes of tsunami warning and tsunami height prediction 

43
Session IV 

Abstracts 

44
Nonlinear site and topography effects in ground motion predictions: 

Observations, Hypotheses and Lessons to be learned 

Dr. Dominic Assimaki

School of Civil and Environmental Engineering

Georgia Institute of Technology

email: dominic@gatech.edu

We present results from our recent work on site and topographic amplification of strong seismic 

motion. Goal of our research is the efficient integration of realistic soil models in broadband 

ground motion simulations, that will allow nonlinear effects to be accounted for in seismological 

predictions while avoiding the pitfalls associated with the need for scarce and sparse geotechnical 

input data, and the tremendous computational effort associated with the spatial and temporal 

resolution of nonlinear site response simulations, had the geotechnical data been available at 

every grid point.

First, we present the development of an empirical relationship between nonlinear site response, 

soil properties, and ground motion. Using 24 downhole array sites in Southern California and a 

series of broadband ground motion synthetics corresponding to various magnitudes and distances 

from a strike-slip fault rupture, we quantify soil nonlinearity in site-specific response analyses, and

show that the factors controlling how strongly nonlinear is site response –or how large is the error 

introduced in ground motion predictions by not accounting for nonlinear site response– are soil 

stiffness, soil-rock impedance contrast, and ground motion intensity and frequency content. Based 

on real geotechnical input data and synthetic ground motions, our study indicates that to 

characterize the susceptibility of a soil profile to nonlinear effects at a given ground motion 

intensity, ground motion prediction equations should be complemented by measures of the soilrock impedance contrast to indicate the potential of the site to trap seismic energy in the near 

surface, as well as measures of the ground motion frequency content, to quantify the likelihood of 

incident seismic wave amplification. We next present results of our work on nonlinear response for 

sites with irregular surface topography. Our hypothesis is that coupling between topography 

effects and soil amplification, namely the presence of irregular surface topography on the surface 

of stratified media, cannot be predicted by the superposition of topography and stratigraphy 

effects alone. We test this hypothesis using numerical simulations and centrifuge experimental 

data. Our preliminary analyses show that topography-stratigraphy effects comprise seismic waves 

trapped in the near surface soil layers, amplified or de-amplified as a consequence of soil-bedrock 

impedance and nonlinear response, and further amplified due to scattering, refraction, mode 

conversion and interference caused by the non-horizontal ground surface. Our numerical and 

small scale experimental data are currently being compiled to determine the conditions when 

coupling of site and topography effects yields amplification in excess of the superposition of the 

two phenomena, and accordingly develop simplified space- and frequency-dependent amplification 

factors that could be used in ground motion predictions to account for topography effects for 

strong ground motion.

While the number of downhole array stations has significantly increased in the US in general, and 

Southern California in particular, the amount of ground motion data recordings that elicit 

nonlinear response are –with a few West Coast exceptions– not statistically significant to allow a 

parametric study on the role and efficient integration of nonlinear effects in seismological models. 

Similarly, recorded evidence of topography effects in the US and Europe is almost exclusively 

from small or distant events, producing by and large weak motion data that may or may not be 

applicable to describe topographic effects for strong motion shaking. In fact, there are no fully 

documented case histories of topographic effects under strong ground motion, while there exist 

very few comprehensive parametric studies of the effects of soil nonlinearity on topographic 

amplification. The unprecedented quality and amount of seismic data recorded by surface and 

downhole seismogram arrays in Japan such as KIK-Net and K-Net provide research opportunities

45
to advance our understanding of nonlinear site response, and to statistically test, evaluate and 

improve our predictive models, but more importantly, to open communication avenues across 

disciplines and across continents. To that end, rather than lessons learned, this presentation 

focuses on opportunities for lessons to be learned on nonlinear site response via international and 

interdisciplinary collaboration.

Figure: (a) Comparison of nonlinear site response model predictions by Assimaki and co-workers to strong 

motion recorded during the 2011 M9.0 Tohoku-Oki event at KIK-Net station mygh004; (b) Google earth 

satellite view, finite element numerical model and parametric study on the ground surface amplification of 

horizontal and vertical acceleration relative to the far field for vertical and inclined incidence of seismic 

waves at K-Net station myg004, which recorded a PGA=2.74g during the 2011 M9.0 Tohoku-Oki event.

46
Strong motion characteristics of the 2011 Tohoku-Oki earthquake 

observed by K-NET and KiK-net

Shin Aoi, Takashi Kunugi, Wataru Suzuki, Nobuyuki Morikawa, 

Hiromitsu Nakamura, and Hiroyuki Fujiwara 

National Research Institute for Earth Science and Disaster Prevention, Tsukuba, Japan 

During the Tohoku-Oki earthquake (Mw 9.0), which was the largest earthquake occurring in 

and around Japan since the recorded history, the ground motions were recorded at 1224 K-NET 

and KiK-net stations. The peak ground accelerations (PGA) exceeded 1g at 20 sites and the 

largest PGA, 2933 gals, was observed at the K-NET Tsukidate station (MYG004). We estimated 

the precise spatial distribution of seismic intensity from the observed data considering the 

near-surface amplification, and found that roughly twenty million people were exposed to a 

shaking of JMA seismic intensity 5+ or larger (>MMI 7). Huge numbers of large aftershocks and 

triggered earthquakes have occurred, some of which were located much nearer to the populated 

urban areas than the main shock and fatalities as well as severe building damages were caused by 

large ground shakings. 

Figure 1. Peak ground accelerations (left) and velocities (right) observed by K-NET 

(triangular) and KiK-net (square) during the 2011 Tohoku-Oki earthquake. 

47
Strong motions of this earthquake are characterized by large JMA seismic intensities and 

PGAs, long durations, and wideness of the area that experienced intense shaking. Although the 

tsunamis were the primary cause of damage, the strong shaking, liquefaction and landslides also 

brought serious destruction. However, it was reported that the damage ratios of houses and 

buildings directly due to shaking were not as high as those for the former earthquakes having 

comparable seismic intensities and PGAs. The recorded ground motions at most stations where 

the seismic intensities and PGAs were large had dominant periods shorter than 0.5 s and 

relatively weak power in the 1 - 2 s period range which has strong influence on the damage of 

few-stories wooden houses. The main reason for the short-period predominance is the 

amplification due to the low-velocity superficial layer and can be roughly explained by empirical 

amplification factors for 0.1 - 0.5 s periods rather than 1 - 2 s. 

48
9/7/2012 

Reconciling precariously balanced rocks with large 

earthquakes on the San Andreas fault system 

Lisa Grant Ludwig1, James N. Brune1,2, Abdolrasool Anooshehpoor2,3, Mathew D. Purvance2,4

and Richard J. Brune5

1

Program in Public Health, University of California, Irvine, CA USA 92697-395 

2

Seismological Laboratory, University of Nevada, Reno NV 89557 

3

U.S. Nuclear Regulatory Commission, Office of Nuclear Regulatory Research, Washington, DC 

20555-0001 

4

Itasca Consulting Group, Minneapolis, MN 55401 

5

3107 Murray Lane., Costa Mesa, CA 92626-2735 

Precariously balanced rocks (PBRs) are fragile landforms (Figure 1) susceptible to toppling by 

earthquakes such that the distribution of PBRs provides insight into the magnitude and 

distribution of earthquake ground motions over thousands of years. We report anomalous PBRs 

near the junction of the San Andreas and San Jacinto plate boundary faults in California, and 

compare PBR fragility to expected ground motions from seismic hazard maps and rupture 

scenarios. Results suggest that groups of PBRs survive in shadow zones of persistent low ground 

motions adjacent to areas of fault complexity where ground motions are attenuated. The 

intersection of the San Andreas and San Jacinto faults appears to be a trans-tensional step-over 

where strain is transferring between the faults. Paleoseismic data permit correlation of rupture 

on both faults, suggesting that simultaneous rupture can occur, with important implications for 

hazard analysis and modeling of fault systems. 

Figure 1

Stack of precariously balanced 

rocks ~12 km from the San 

Andreas fault at its junction 

with the San Jacinto fault.

49
Session V 

Abstracts 

50
Betting against the house and peer-to-peer gambling: a Monte Carlo view of earthquake forecasting

J. Douglas Zechar & Jiancang Zhuang

Using an analogy between prediction and gambling, we consider earthquake forecasts as wagers of 

professional reputation. We have previously discussed a "gambling score" based on comparing earthquake 

predictions with a reference model, and this is akin to betting against the house: the reference model is the 

oddsmaker and a gambler can win a large amount in a single bet. One might criticize this as an unstable 

score because it is sensitive to the occurrence of low-probability events, and constructing an appropriate 

reference model is itself a difficult problem. There is another gambling paradigm in which bettors 

compete directly against each other and share the winnings among themselves--this is sometimes called 

peer-to-peer betting. This too has an analogue in earthquake forecasting and model development, where it 

is increasingly common to compare and rank multiple forecasts which have a common format. In this 

presentation, we consider the case of gridded rate forecasts, in which one wants to forecast the distribution 

of seismicity (in space, time, magnitude, etc.) rather than individual events. We treat each grid node as a 

separate wager in which each forecast can abstain or bet one credit of reputation distributed over the 

number of expected earthquakes. After the observation period, each forecast that bet on this node is 

rewarded with an amount that is proportional to its correct wager. We applied this method to compare 

forecasts from the RELM (Regional Earthquake Likelihood Models) five-year experiment in California. In 

this presentation, we demonstrate how a peer-to-peer gambling score can be calculated in a roundtable 

setting to simulataneously compare multiple earthquake forecasts, and we also present a head-to-head 

mode which we compare to using a likelihood ratio metric. We also discuss how the gambling score can 

be used when developing new seismicity models.

51
Information services on earthquake prediction and forecast of JMA

Kohei Nagata 

Earthquake Prediction Information Division, Seismological and Volcanological Department, 

Japan Meteorological Agency 

k_nagata@met.kishou.go.jp 

The Japan Meteorological Agency (JMA), as the sole national authority responsible for issuing 

weather/earthquake/tsunami warnings in Japan, is required to provide reliable and timely information to 

governmental agencies and residents for the purpose of prevention and mitigation of natural disasters. 

On earthquake prediction and forecast, the JMA issues three different types of information: information 

on the Tokai Earthquake, information on seismic activity in the eastern Izu district and information on 

prospect of aftershock activity for major earthquakes. 

Prediction and Information Services for the Tokai Earthquake 

The Tokai Earthquake is a megathrust earthquake expected to occur in the near future along the 

Suruga Trough (Figure 1). Historically, the plate boundary along the Suruga trough has been ruptured 

every 100-150 years as a part of focal regions of similar megathrust earthquakes along the Suruga and 

Nankai Trough. However, in the last Tonankai Earthquake (1944, M7.9) and Nankai Earthquake (1946, 

M8.0), the plate boundary along the Suruga trough was not ruptured. This seismic gap area of the plate 

boundary, assumed as the focal area of the Tokai Earthquake, has not slipped for more than 150 years. 

Since the expected damage caused by the Tokai Earthquake is enormous, and there lies a possibility 

of short-term prediction, the Japanese government enacted the Act on Special Measures for Large-scale 

Earthquakes for disaster prevention. In the framework of this law, the JMA has undertaken the duty for 

predicting the Tokai Earthquake. 

The prediction of the Tokai earthquake is to be performed based on the detection and identification of 

pre-slip, derived from friction constitutive law.Such pre-slip is expected to occur on the upper boundary 

of the Philippine Sea Plate before the Tokai Earthquake. In order to detect the pre-slip, the JMA 

monitors crustal deformation with various kinds of observation instruments, such as strainmeters, 

tiltmeters and GNSS equipments installed in and around the assumed focal region of the Tokai 

Earthquake in collaboration with related institutes, on around-the-clock basis. Seismometers are also 

more densely installed in this region than in the other regions in Japan. 

If some anomaly is detected, the JMA issues Information on the Tokai Earthquake to enable 

preparatory actions and emergency measures for earthquake disaster prevention. According to the 

probability of the anomaly as a precursor, the information is categorized into three types: Investigation 

Report on Tokai Earthquake Prediction, Tokai Earthquake Watch, and Explanatory Information on Tokai 

Earthquake Warning. 

Information on Seismic Activity in the Eastern Izu District 

The eastern Izu district, one of active volcanic regions in Japan, has suffered Earthquake swarms 

52
many times. Investigation of past 49 earthquake swarms since 1978 has clarified that earthquake swarms 

in this district are controlled by magma behavior, and can be quantitatively forecast in terms of crustal 

deformation around the swarm area. Using this relation, the number of earthquakes in the whole period 

of the seismic activity can be estimated from the amount of strain change observed at the neighboring 

site in the early stage of the activity, which reflects the amount of magma injection. From the estimated 

number of earthquakes, we estimate the number of earthquakes by magnitude assuming the 

Gutenberg-Righter law. With this method, the JMA is to announce the expectation for maximum 

magnitude, maximum seismic intensity, duration of the activity and number of earthquakes to be felt as 

the information on seismic activity in the eastern Izu district since 2011. 

Prospect of Aftershock Activity 

The JMA has issued the information on prospect of aftershock activities for remarkable earthquakes 

since 1999 based on two well-known empirical relations. One is the modified Omori formula which 

expresses the way aftershocks decrease. The other is Gutenberg-Righter law, which can also explain 

aftershock activities well. Combining these relations enables probabilistic evaluation for aftershock 

activity with seismic data available at an arbitrary time. The information on prospect of an aftershock 

activity includes description of the expectation for the number of earthquakes larger than a certain 

magnitude expected to occur for the next several days and its probability value, duration of the activity, 

and maximum intensity in addition to description of the observed earthquake activity. 

Izu Earthquake Swarm Area 

Figure 1. Assumed focal regions of the Tokai, Tonankai and Nankai Earthquakes and Izu 

earthquake swarm area.

53
Earthquake Early Warning of JMA 

- The 2011 off the Pacific coast of Tohoku Earthquake and its aftershocks – 

Yasuyuki YAMADA 

Earthquake and Tsunami Observations Division, Seismological and Volcanological 

Department, Japan Meteorological Agency 

yamada1228@met.kishou.go.jp 

Earthquake Early Warning (EEW) is to announce the expected seismic intensity and 

arrival time of strong motion before its arrival by detecting and quickly analyzing 

seismic waveform data at stations near the epicenter. The Japan Meteorological Agency 

(JMA) started to provide EEW to a limited number of users from August 2006 and to 

the public through TV and radio in October 2007. The Meteorological Service Act was 

amended in December 2007 to legally provide that the EEW be announced as ”forecast” 

and ”warning” of strong ground motion caused by an earthquake. EEW (warning) is 

issued when seismic intensity of 5-lower or larger (on JMA scale) is estimated, whereas 

EEW (forecast) is issued when the estimated intensity is between 3 and 4, or magnitude 

of the detected earthquake exceeds 3.5. 

EEW is updated as available data increases with elapsed time. Accordingly EEW is 

issued repeatedly with improving accuracy for a single earthquake. 

On March 11 2011, the 2011 off the Pacific coast of Tohoku Earthquake (Mw9.0) 

occurred and caused strong ground motion around northeastern Japan. 

The fault rupture started at 14:46:18.1 (JST), and the EEW system was triggered when 

station OURI (138km from the epicenter) detected the initial P wave at 14:46:40.2. The 

first EEW (forecast), among the 15 announcements for the mainshock, was issued 5.4 

seconds after the detection. The waveform started with small amplitude, which was 

comparable to noise level for displacement. The small amplitude did not indicate that 

the initial rupture of the Mw 9.0 event was large, and did not suggest that the entire 

scale went to be incredibly enormous. Eight point six (8.6) seconds after the detection, 

the estimated intensity exceeded the warning threshold (5-lower) and the JMA issued 

the fourth EEW (first warning) to Tohoku district. The warning was automatically 

broadcast through TV, radios and cellular phones (by using Cell Broadcast Service) 

more than 15 seconds before the actual intensity of ground motion reached to the 

threshold. However, warned area was apparently smaller than the area where seismic 

intensity 5-lower or more was observed, due mainly to the focal area extent 

underestimation. 

54
After the mainshock to December 2011, the JMA issued 96 warnings and 3751 

forecasts for its quite active aftershocks and induced earthquakes. (Note that, from 

October, 2007 to March, 2011 (41 months), the JMA issued 17 warnings and 1928 

forecasts). 

On the other hand, some inaccurate warnings were issued after the mainshock. From 

March to December 2011 the JMA issued 27 ”false-alarms” in which seismic intensity 

5-lower or larger was expected but the real intensities were 2 or lower. 

The cause was investigated and was found out that two or more earthquakes occurred 

simultaneously over the wide area, which tricked the system as if one huge event 

happened in somewhere. 

In this presentation, we will present evaluation of the performance of EEW issuance, 

lessons learned from the earthquakes and various efforts to improve EEW of the JMA. 

Figure 1. EEW lead time (in seconds) and observed seismic intensity at the 2011 off 

the Pacific coast of Tohoku Earthquake

7

6Upper

6Lower

5Upper

5Lower

4

Seismic intensity

(JMA scale)

55
Early Warning on the US West Coast 

John E. Vidale and Paul Bodin

I’ll quickly review the status of US West Coast earthquake early warning (EEW) efforts funded 

by the USGS and the Moore Foundation, then highlight the particular challenges of EEW for 

Cascadia. 

The Cascadia subduction zone offers great utility from earthquake early warning for the Puget 

Sound, Portland, Vancouver, and the tsunami-vulnerable coast. The 1000-km length allows 

minutes of warning when a megaquake starts at a distance, as is likely. The 10,000-year record 

of the last several dozen great earthquakes from offshore turbidites allows good guessing of the 

chance of a big earthquake growing into a turbulent giant. We are far enough into the 500-year 

M9 cycle to have 150% of the long-term odds – 1/300 odds each year. The southern stretch of 

Cascadia, which is prone to M8s as well as M9s, is even more primed for action. 

Challenges are also outsized. Instrumentation is relatively sparse. Discrimination between a 

wide range of possible styles and depths of strong earthquakes will be difficult. Means of 

relaying warnings, discussions with potential users, and long-term funding are not yet mature. 

The UW and UC Berkeley, with the support of the Moore Foundation, are constructing a 

prototype early warning system. We are beginning with duplicate installations of the ElarmS 

algorithm in Seattle and Berkeley, and sharing data across borders. We are also exploring 

inclusion of GPS displacements in verifying the magnitude and development of large 

earthquakes. 

56
Session VI 

Abstracts 

57
Potential contributions of Seafloor Geodesy to understanding 

slip behavior along the Cascadia Subduction Zone 

C. David. Chadwell, 

Scripps Institution of Oceanography, University of California San Diego

We propose an experiment to measure crustal deformation along Cascadia that crosses the entire region of 

a subduction zone from the incoming plate, the offshore continental slope and the sub-aerial continent 

(See Figure). There are two primary objectives to address with seafloor geodetic monitoring of 

Cascadia. What is the stick-slip behavior along the subduction thrust fault from the deformation front 

toward the coast where land geodetic data are controlling? Where is this offshore behavior located? 

Generally there are three possibilities. Stable sliding could occur from the deformation front to landward, 

i.e., no stick behavior and no transfer of elastic strain to the upper plate. This has a low probability as 

elastic strain is observed onshore along Cascadia, except at approximately 44°40 ́ where [Burgette et al., 

2009] observe no significant uplift along a leveling line and note that no stick or locking is required on 

the thrust fault to fit their data. 

The second possibility is reported in most of the published models [Fluck et al., 1997; Wang et al., 2003; 

McCaffrey et al., 2007; Burgette et al., 2009]. They assume stick behavior from the deformation front to 

some distance landward where it decays linearly or exponentially to completely stable sliding. Land 

geodetic data are too far from the deformation front to resolve whether or not stick starts at the front. 

Likewise, though land geodetic data are best fit with a transition from fully stick or locked to a decay and 

ultimately fully stable sliding, this boundary occurs offshore and is not strongly resolved leading to 

variability among the published models. Seafloor geodetic data located directly above the thrust fault 

where the changes in slip behavior occur should be able to resolve more strongly their magnitude and 

location. 

The third possibility is a variation of the second where at the toe material is assumed to require some time 

and space to consolidate before supporting stick-like behavior. The situation is a subtle one because even 

though the material at the toe may not be under elastic strain it most likely moves with the material that is 

just downdip and locked. Wang [2007] has shown three scenarios. Gagnon et al., [2005] observed the 

toe offshore Lima Peru contracting significantly. This suggests it is reasonable to conclude the toe is not 

stationary with respect to the upper plate, but that generally it must move either under elastic strain or 

simply kinematically with the material downdip. Though the difference is small between frictionless and 

locked it could be detected with sufficient duration of seafloor geodetic monitoring. This would address 

the question directly as to the state of stick slip behavior out near the front as noted by [Avouac, 2011]. 

An additional target for seafloor geodesy is measuring any interseismic elastic deformation of the 

incoming plate and what role this may have in understanding the stick slip behavior on the thrust fault 

near the deformation front. This topic has received scant attention to date primarily due to a lack of 

observations. There are two recent examples, however, that suggest that some amount of the elastic strain 

due to convergence is accumulated in the incoming plate. Lay et al. [2009] observed in the Kuril Islands 

a subduction thrust fault earthquake in 2006 followed by a normal fault earthquake in 2007 in the 

incoming plate. They suggest that about half of the interseismic strain accumulation was accommodated 

58
elastically within the incoming plate. Chadwell [2007] reported an observation with GPS-Acoustics at 

44°40 ́ offshore central Oregon that is about half the expected long-term rate based on the geomagnetic 

anomaly reconstructions. A likely interpretation is that a significant amount of the convergent motion is 

accumulated as elastic strain in the plate offshore. Interestingly, this would be consistent with Burgette et 

al., [2009] finding that no stick (or locking) is required to fit the leveling data at this same latitude along 

the CSZ. 

Geodetic arrays in place before a subduction thrust earthquake provide 

more direct measurements of slope response than relying on land 

geodetic data alone. This was first demonstrated by Matsumoto et al. 

[2006] offshore Japan and of course most recently following the 

Tohoku-Oki Earthquake where 24 m was observed at one GPS-A site 

and 31 at another [Sato et al., 2011; Kido et al., 2011]. These 

measurements on the sea floor along with modeling of tsunami waves 

passing over deep sea pressure sensors imply 40-50 m displacement 

on the thrust fault. Early result based solely on land geodetic data 

estimated only about 25 m of shift along the thrust fault. The direct 

observation of the co-seismic displacement is unprecedented. 

However, the more important contribution from seafloor geodesy may 

be measurements of interseismic strains in the slope and incoming plate 

and using these observations to map the behavior of stick-slip for estimating more precisely the rupture 

potential. Figure shows a notional design of a seafloor geodetic array for Cascadia to be further refined 

with community input.

References: 

Avouac, J.-P., The lessons of Tohoku-Oki, Nature, 474, 1–2, 2011. 

Burgette, R. J., R. J. W. II, and D. A. Schmidt, Interseismic uplift rates for western Oregon and along-strike variation in locking 

on the Cascadia subduction zone, J. Geophys. Res., 114, 2009. 

Chadwell, C. D., Deformation of the Converging Juan de Fuca Plate Offshore Central Oregon, Eos. Trans.AGU, 88(52), Fall 

Meet., Suppl., Abstract T53A–1126, 2007. 

Fluck, P., R. D. Hyndman, and K. Wang, Three-dimensional dislocation model for great earthquakes of the Cascadia subduction 

zone, J. Geophys. Res., 102, 20,539–20,550, 1997. 

Gagnon, K. L., C. D. Chadwell, and E. Norabuena, Measuring the onset of updip locking in the Peru-Chile Trench with GPSAcoustic measurements, Nature, 434, 205–208, 2005. 

Kido, M., Y. Osada, H. Fujimoto, R. Hino, and Y. Ito, Trench-normal variation in observed seafloor displacements associated 

with the 2011 Tohoku-Oki earthquake, Geophys. Res. Lett., 38, L24303, doi:10.1029/2011GL050057, 2011. 

Lay, T., H. Kanamori, C. Ammon, A. Hutko, K. Furlong, and L. Rivera, The 2006-2007 Kuril Islands great earthquake sequence, 

J. Geophys. Res., 114, 2009. 

McCaffrey, R., A. I. Qamar, R. W. King, R. Wells, G. Khazaradze, C. A. Williams, C. W. Stevens, J. J. Vollick, and P. C. Zwick, 

Fault locking, block rotation and crustal deformation in the Pacific Northwest, Geophys. J. Int., 169, 13151340, 2007. 

Wang, K., R.Wells, S.Mazzotti, R. D. Hyndman, and T. Sagiya, A revised dislocation model of interseismic deformation of the 

Cascadia subduction zone, J. Geophys. Res., 108, 2003. 

Wang, K., Elastic and viscoelastic models of crustal deformation in subduction earthquake cycles, in TheSeismogenic Zone of 

Subduction Thrust Faults, edited by T. Dixon and J. Moore, vol. 2, pp. 540–575, 2007. 

Matsumoto, Y., T. Ishikawa,M. Fujita, M. Sato, H. Saito, M. Mochizuki, T. Yabuki, and A. Asada, Weak interplate coupling 

beneath the subduction zone off Fukishima, NE Japan, inferred from GPS/acoustic seafloor geodetic observation, 

Earth Planets Space, 60, e9–e12, 2008. 

Sato, M., T. Ishikawa, N. Ujihara, S. Yoshida, M. Fujita, M. Mochizuki, and A. Asada, Displacement Above the Hypocenter of 

the 2011 Tohoku-Oki Earthquake, Science, 332, 1395, 2011. 

59
Performance Tests of Real-Time Permanent Displacement Estimates and Rapid Rupture 

Characterization From Real-Time High-Rate GPS

Sarah E. Minson, John O. Langbein, Jessica R. Murray, Joan S. Gomberg

USGS Earthquake Science Center

Real-time high-rate GPS data present many advantages for rapid estimation of earthquake ruptures. 

Chief among them is the ability to provide spatial resolution of an earthquake rupture's static slip 

distribution and to obtain rapid moment estimates that do not saturate for large events. Although realtime high-rate GPS data suffer from relatively high noise, low sensitivity to small earthquakes, and a 

dearth of operating and telemetered instruments, these data still provide a valuable enhancement to 

existing seismic monitoring. 

We will present a prototype framework for rapid estimation of distributed slip models from real-time 

estimates of permanent surface displacement. In order to assess the immediate threat posed by an 

earthquake, such models must be accompanied by realistic confidence bounds on model parameters. 

Our goal is to develop an approach that balances computational efficiency with inversion methodologies 

that properly estimate the uncertainties in finite source models. If this modeling process can be made 

sufficiently speedy, the slip model could potentially be updated in near-real-time as the earthquake 

rupture evolves. 

The first part of our presentation focuses on performance tests of new methods relative to existing 

techniques for calculating the accumulated permanent displacement in real-time from GPS waveforms 

from a variety of earthquakes of different magnitudes and located in different tectonic settings. These 

methods need to be evaluated for both large earthquakes whose coseismic time series are dominated 

by static offsets and moderate magnitude earthquakes for which the dynamic offsets dwarf the static 

component of deformation. We compare the various algorithms based on how quickly they provide an 

initial estimate of accumulated displacement and the delay (if any) following the passing of the seismic 

waves in returning a final, accurate measurement of the permanent surface displacement. Variation in 

rupture and data characteristics can greatly affect the performance of real-time offset-estimation, and 

different methodologies may be preferable depending on whether an application prizes earlier 

information over more accurate information about the evolving static offset. 

In the second part of our presentation, we discuss how to best estimate a distributed coseismic slip 

model in near-real-time. While real-time high-rate GPS data is becoming more widely available, 

especially for regions of high seismic hazard in California and the Pacific northwest, station coverage is 

still limited and thus the spatial extent of rupture can still be quite poorly constrained. To handle this 

situation, we are developing techniques which combine Bayesian inference with linear regression to 

quickly produce rupture models with robust confidence bounds that can be used to evaluate the quality 

of the inversion results. 

60
Integrating)GPS)and)Radar)Geodetic)Imaging)Observations)with)Models)for)

Earthquake)Response)and)Planning)Additional)Data)Collection)

Andrea!Donnellan,!Jay!Parker,!Robert!Granat,!Margaret!Glasscoe!

Jet!Propulsion!Laboratory,!California!Institute!of!Technology

Geoff!Blewitt

University!of!Nevada!Reno

John!Rundle

University!of!California,!Davis

UJNR)Abstract)

For$session:$Real-time$Monitoring$of$seismic,$geodetic$and$strain$measurements,$

Seafloor$GPS$

Rapid!GPS!solutions!are!making!it!possible!to!quickly!infer!details!of!fault!ruptures,!

which!can!provide!information!about! fault!activity,!areas!of!damage,!and!potential!

aftershocks.!Radar!in!the!form!of!UAVSAR!and!spaceborne!interferometric!synthetic!

aperture!radar!(InSAR)!also!provides!information!about!crustal!deformation,!though!

often! not! as! rapidly.! However,! the! results! have! proved! useful! to! showing! where!

creep! has! occurred! on! faults! neighboring!a!major! rupture! such!as! occurred!in! the!

2010!El!Mayor!–!Cucapah!event.!Software!such!as!QuakeSim’s!simplex!program!has!

been!used!to!rapidly!invert!for!one!or!more!faults!following!events,!often!identifying!

moment!release!larger! than! the!seismic!moment!and!deformation!on! faults!off! the!

main! rupture.! Rapidly! and! readily! available! geodetic! data! and! reliable! and!

iteratively! refined! models! from! QuakeSim! are! fed! into! decision! support! systems!

such as! EWDECIDER! to! produce! products! for! decision! makers! that! can! be! used! to!

help!focus!response!efforts.!!These!include!deformation!gradient!maps!and!tilt!maps!

that! can! be! calculated! and! produced! both! from! observed! data! and! models.! Fault!

parameters! can! also! be! ingested! into! models! such! as! Virtual! California! to! infer!

aftershock! location! and! likelihood! and! probabilities of! future! large! earthquakes.

Such!models!are!being!run!to!estimate!earthquake!likelihood!in!Los!Angeles!due!to!

the! El! Mayor! –! Cucapah! and! Landers! earthquake.! Detailed! potential! surface!

deformation!can!be!calculated!to!steer!future!data!collection!efforts!to!areas!of!high!

probability!for!additional!earthquakes!or!ground!deformation.!UAVSAR!data!will!be!

collected! in! late! September! 2012! over! the! Brawley! swarm! region! to! further!

understand! the!regional!deformation!pattern!associated!with! that!event.!Statistical!

models! of! time! series! implemented! in! the! RDAHMM! software! and! its! extension!

allow! for! the! detection! of! local! or! regional! anomalies! observed! in! GPS!

data.! !Application! of! these! models! to! high! rate! GPS! collected! before! and! after! the!

2011! TohokuWOki! earthquake! provided! deeper! understanding! of! the! dynamics! of!

the! crustal! motion! around! the! time! of! the! earthquake! as! well! as! indications! of!

subsequent!aseismic!activity!at!a!distance!from!the!main!rupture!zone.!

61
Rapid assessment of high seismic intensity areas for mega-earthquake using 

satellite SAR data

Ken Xiansheng Hao1, Tomokazu Kobayashi2 and Hiroyuki Fujiwara1

1 National Research Institute for Earth Science and Disaster Prevention, Japan 

2 Geospatial Information Authority of Japan, Japan

hao@bosai.go.jp

The 2008 Mw 7.9 Wenchuan earthquake devastated huge regions and triggered over 

11,000 catastrophic landslides, slope collapses and debris flows spanning 300 km along the 

Longmen Shan (LMS) fault zone. The great disaster resulted in over 80,000 fatalities, 

350,000 injuries and 46,574 affected villages. 

Figure 1. A comparison of the displacement using a pixel-offset analysis with isoseismal 

contours obtained from field investigations for the Mw7.9 Wenchuan earthquake (star, 

epicenter). (a) The displacements, indicated by offset [m] with and warm/cold color scales, 

represent the forward or away from the satellite in the ground-to-satellite line of sight direction, 

superimposed by GPS-observed coseismic offsets (red arrows, scale proportional to 2.43 m of 

maximum horizontal displacement), and by locations (plus signs) of the major coseismic fault 

scarp. (b) The isoseismal contours indicated by intensity VI to XI, superimposed by locations 

of the major landslides (solid triangles), and active faults (brown lines). (Higher resolution 

images can be found (Hao et al., 2012). 

62
The Mw 7.9 earthquake epicenter was located on the southwestern end of the LMS faults; 

however, the most damaged regions were Yinxue (YX, seismic intensity XI), Beichuan (BC, 

XI) and Qingchuan (QC, IX), distributed over a distance of 290 km toward the northeast as 

the LMS faults ruptured (Hao et al., 2009). Lack of information on inaccessible areas such as 

mountainous regions led to more fatalities and injuries. 

On-line instrumental surveys of seismic intensity have dramatically revolutionized the 

method for assessing earthquake damage from the conventional field investigations. More 

than 4,200 strong-motion seismographs were installed to survey seismic intensity in Japan 

and allow information to be automatically publicized within minutes following an earthquake. 

Unfortunately, the other countries frequently affected by earthquakes lack such dense array of 

the seismographs leading to delayed reporting. For example, after the Wenchuan earthquake, a 

field investigation-based seismic intensity map (Figure 1b) was not produced until 14 weeks 

post-quake due to widespread damages. As earthquake survivors in devastated regions waited 

for rescue, responders had no detailed knowledge of seismic intensity distribution. An 

assessment of damage intensity is crucial to quickly determine extreme disaster regions 

without reliance on slower, resource intensive methods such as ground observations and field 

surveys. 

 A novel method of rapidly assessing high seismic intensity areas is proposed by using 

satellite geodetic surveys after the Wenchuan earthquake. We re-compute pixel displacements 

using ALOS/PALSAR data (Kobayashi et al., 2009), and densely setup the profiles of the 

pixel displacements across the region. Our profiles provide detailed information of areas 

within higher seismic intensity contours, especially for high mountainous areas where limited 

information was available. Vast amounts of field investigations provide valuable 

supplementary information about field fault scarps, landslides and seismic intensity contours. 

By analyses of displacements and seismic intensity contours, we propose a criterion of the 

displacement-to-intensity to qualitatively judge if high seismic intensity has occurred. 

Displacements of => 1 m may correspond to areas where higher intensities has occurred (> 

IX), and displacements of < 1 m may relate to areas where intensity < VII has occurred. We 

reveal that seismic intensity IX extended into VIII areas in western mountainous regions 

based on the criterion. Following mega (i.e. > M7) inland earthquakes, ground displacements 

of above one meter may indicate the possibility that the area suffers from high seismic 

intensities. This result calls for further study and cooperation; such as reduce the latency with 

more dedicated cooperation and improving accuracy. 

Hao, K. X., H. Si, H. Fujiwara, and T. Ozawa (2009), Coseismic surface-ruptures and crustal deformations of the 2008 Wenchuan 

earthquake Mw7.9, China, Geophys. Res. Lett., 36, L11303, doi:10.1029/2009GL037971. 

Hao, K. X., T. Kobayashi, and H. Fujiwara (2012), Rapid Assessment of High Seismic Intensity Areas of the 2008 Mw 7.9 Wenchuan 

Earthquake Using Satellite SAR Data, Seis. Res. Lett., July/August 2012, v. 83, p. 658-665, doi:10.1785/0220110117. 

Kobayashi , T., Y. Takada, M. Furuya, and M. Murakami (2009), Locations and types of ruptures involved in the 2008 Sichuan 

earthquake inferred from SAR image matching, Geophys. Res. Lett., 36, L09304, doi:10.1029/2009GL038675. 

63
Real-Time Monitoring at the USGS National Earthquake Information Center: Past, 

Present, Future 

G.P. Hayes, P.S. Earle, H.M. Benz, D.W. Wald 

UJNR Panel Meeting, Denver, October 2012 

Over the past decade, the US Geological Survey (USGS) National Earthquake 

Information Center (NEIC) has evolved from an operation primarily targeting the 

reporting of basic earthquake parameters in near-real time (i.e., location, origin 

time, magnitude) to one which leads global response to significant earthquakes 

through the production of a number of sophisticated products aimed at a broad 

characterization of source parameters and earthquake impact. This has been 

facilitated through (1), the evolution of the NEIC into a 24/7 operational facility, 

rather than being dependent on on-call analysts and researchers: (2), the 

development and operation of a new generation of seismic acquisition, processing 

and distribution system known as Bulletin Hydra: (3), expansions in global 

monitoring, seismic station density and quality: (4), accompanied improvements in 

our ability to rapidly characterize earthquake magnitude, using methods such as 

Empirical Green’s Function deconvolution and the W-phase centroid moment tensor 

(CMT) inversion, and (5), the production and implementation of a number of key 

products – for example, ShakeMap, PAGER, and Finite Fault Modeling – via both in 

house expertise and academic partnerships. 

In 2004, the NEIC lacked a comprehensive set of tools to provide rapid and robust 

magnitudes of the M 9.1 Sumatra earthquake, and to properly characterize the 

source mechanism and societal impact of the event. Thanks to the developments 

since, discussed in more detail in this presentation, following the 2011 Tohoku 

earthquake the world was aware of the great size of the event in minutes, instead of 

the hours to days it took for similar information to be disseminated in 2004. 

Today, our response challenge has evolved to one of addressing how we refine the 

tools we use to work better in tandem, and how to better streamline our external 

coordination efforts with other global and national earthquake agencies. Our 

64
research interests are aligned with the identification and application of approaches 

that help improve the speed and accuracy of earthquake response, and advance 

studies of earthquake risk reduction. We conclude by discussing some of these 

applications and developments, how they are being used for both real-time 

activities and longer-term research, and how we hope to use them to drive further 

improvements in earthquake monitoring and response in the future. 

Figure: Idealized response capabilities using regional applications of the W-phase 

CMT inversion, based on real time data streams available at the NEIC, and statistics 

of data requests versus usage in past W-phase inversions. Given a rapid trigger of 

approximate earthquake location and size, colors indicate how quickly an accurate 

magnitude and CMT mechanism could be available at a given location, assuming that 

approximately 20 data channels of data are needed beyond 5 degrees from the 

source to produce a reliable solution. 

65
NSF's EarthScope Program – Introduction and Updates 

Chuck Estabrook 

Program Director for EarthScope 

In the 90's started the EarthScope program. EarthScope is an ambitious, multifaceted 

program to investigate the structure, dynamics, and history of the North American 

continent. EarthScope’s vision is to use North America as a natural laboratory to gain 

fundamental insight into how Earth operates. EarthScope provides researchers with rich 

data sets to image, sample, and monitor the continent and underlying mantle at a 

resolution never before attempted. 

The program is an initiative of the Division of Earth Sciences at the National Science 

Foundation, and it began as a multiyear effort in 2003. Ideas for the program started in 

the 90's. It is now in its ninth year and is expected to continue until 2018. 

At NSF EarthScope is divided into the Facility, the Science program, the National Office

and Education and Outreach. The Facility is composed of four parts: USArray (a seismic 

and magnetotelluric network including the Transportable Array which is now 

approaching Washington DC), the Plate Boundary Observatory (geodetic and seismic 

network), San Andreas Fault at Depth (SAFOD), and GeoEarthScope (imagery and 

geochronology). The Science funds about 20 projects/year that use data from the ES 

Facility. 

This talk will concentrate on presenting some of the latest results from EarthScope with 

an emphasis of topics of interest to NASA. Presently there are 400 seismic stations in the 

eastern North America with plans for moving the equipment to Alaska. PBO is fully 

deployed and operational, and NSF is now accepting proposals for the future use of the 

SAFOD facility. 

66
Session VII (Posters) 

Abstracts 

67
Ocean bottom seismic and tsunami network along the Japan Trench

Toshihiko Kanazawa, Kenji Uehira, Shin’ichi Noguchi, Shin Aoi, Takashi Kunugi, 

Takumi Matsumoto, Yoshimitsu Okada, Shoji Sekiguchi, and Katsuhiko Shiomi 

National Research Institute for Earth Science and Disaster Prevention, Tsukuba, Japan 

Huge tsunami, which was generated by the 2011 off the Pacific Coast of Tohoku Earthquake 

of M9 subduction zone earthquake, attacked the coastal areas in the north-eastern Japan and gave 

severe casualties (about 20,000 people) and property damages in the areas. The present tsunami 

warning system, based on land seismic observation data, did not work effectively in the case of 

the M9 earthquake. For example, real tsunami height was higher than that of forecast by this 

system. It is strongly acknowledged that marine observation data is necessary to make tsunami 

height estimation more accurately. Therefore, new ocean bottom observation project has started 

in 2011 that advances the countermeasures against earthquake and tsunami disaster related to 

subduction zone earthquake and outer rise earthquake around the Japan and Kuril Trenches. A 

large scale ocean bottom cabled observation network is scheduled to be deployed around the 

Japan Trench and the southern Kuril Trench by 2015. The network is consisted of 154 ocean 

bottom observation stations. Ocean bottom fiber optic cables, about 5800 km in total length, 

connect the stations to land. Observation stations with tsunami meters and seismometers will be 

placed on the seafloor off Hokkaido, off Tohoku and off Kanto, in a spacing of about 30 km 

almost in the direction of East-West (perpendicular to the trench axis) and in a spacing of about 

50 - 60 km almost in the direction of North-South (parallel to the trench axis). Two or more sets 

of tsunami meters and seismometers will be installed in one station for redundancy. Two sets of 

three component servo accelerometers, a set of three component quartz type accelerometers 

(frequency outputs), a set of three component velocity seismometers will be installed, and two 

sets of quartz type depth sensors (frequency outputs) will be installed as tsunami meters. Tsunami 

data and seismometer data will be digitized at sampling frequency of 10 Hz and 100 Hz, 

respectively, and will be added clock information at land stations. These digitized data will be 

transmitted to the NIED data centers, JMA, universities and so on, using IP network. The 

network is capable of quickly and precisely catching seismic motions and sea level changes near 

earthquake sources along remote subduction zone, which will be utilized to monitor large 

earthquakes and tsunamis, to transfer prompt and precise warnings, and to clarify the detailed 

crustal structure. 

68
 

Figure 1. An ocean bottom cabled observation network composed of seismometers and 

tsunami meters is planned to be deployed at 154 locations on the deep sea bottom 

along the southern Kuril Trench, the Japan Trench and the Sagami Trough. 

69
Developing a GEONET Real-time Processing System for Rapid Earthquake Modeling 

Satoshi Kawamoto 1, Kohei Miyagawa 1, Basara Miyahara 1, Kazunori Yamaguchi 1, 

Tomoaki Furuya 1, Kazuki Sakai 1, Yuki Hatanaka 1, Takuya Nishimura 1, 

Satoru Nemoto 1, Hiromichi Tsuji 1, Yusaku Ohta 2, Ryota Hino 2, Motoyuki Kido 2, 

Takeshi Iinuma 2, Hiromi Fujimoto 2 and Satoshi Miura 3

1 Geospatial Information Authority of Japan 

2 Graduate School of Science, Tohoku University 

3 Earthquake Research Institute, The University of Tokyo 

s-kawamoto@gsi.go.jp 

1. Introduction 

The 2011 off the Pacific Coast of Tohoku Earthquake (Mw 9.0; hereafter Tohoku 

earthquake) caused catastrophic tsunami damage. It indicates us several problems for 

improving a tsunami early warning system. Overcoming magnitude saturation is one of 

the keys to improve forecasting of the large tsunami. It has been suggested that 

real-time GNSS processing could contribute a rapid determination of earthquake 

magnitude (e.g., Blewitt et al., 2006) and that it could supplement the operating 

tsunami warning system mainly based on the seismometer network. “GEONET” could 

contribute it, which is Japan’s nationwide GNSS network consists of over 1,200 

permanent stations streaming 1Hz data. Here, we describe our challenge to determine 

the earthquake magnitude with GEONET data in real-time. 

2. System Overview 

Now GSI and Tohoku University are underway to develop a new GEONET 

real-time processing system together to help fast tsunami forecast. The goal of the 

system is to provide displacements fields and earthquake magnitude as fast as possible 

after earthquakes. The system features include: 

 implementation of “RTKLIB 2.4.1” (Takasu, 2011) for processing real-time GNSS 

data of whole GEONET network; 

 detecting large earthquakes automatically without seismometer; 

 estimation of a rectangular fault model including moment magnitude; 

 providing the results described above as a forecast guidance; 

3. Development Progress 

Starting on 6 April 2012, the prototype has implemented “RAPiD” (Ohta et al. 

70
2012), which was developed as an algorithm for auto-detection of permanent 

displacements from timeseries of GNSS positioning, and being in operation processing 

about 150 baselines with RTKLIB 2.4.1. If the system detects displacements, it will start 

monitoring ground motions of rover stations. When the strong ground shaking is over, 

the prototype sends permanent displacement field and detected time via e-mail to 

operators. 

Real-time GNSS processing shows the standard deviation of 1.6 cm in horizontal 

component for two months of operation. It suggests that the real-time positioning is 

enough precise to detect a giant earthquake like the 2011 Tohoku earthquake adequately. 

However, false detections of permanent displacements were often found during this 

experimental period. These are caused by large noises of GNSS positioning due to 

atmospheric signal delays and temporary suspension in real-time streaming data. 

Therefore we are continuing to refine the prototype. 

4. Future Plan 

The false detections found would be problem. Kobayashi et al. (2012) proposed a 

new algorithm that used adjacent stations simultaneously and demonstrated it would 

dramatically reduce false detections. By the end of this year, we will upgrade the 

prototype with implementing the algorithms for reducing false detections as well as 

estimation of a rectangular fault model. 

The system is planned to be in full operation after the next fiscal year. Then we will 

start to provide the results to disaster prevention organizations. 

Figure 1. An example of flow of the information provided by the system. 

71
Asia-Pacific Region Global Earthquake and Volcanic Eruption Risk 

Management (G-EVER) project 

Yasuto Kuwahara 

Geological Survey of Japan, AIST 

y-kuwahara@aist.go.jp

The first Workshop of Asia-Pacific Region Global Earthquake and Volcanic 

Eruption Risk Management (G-EVER1) was held in Tsukuba on February 22-24, 

2012. The workshop focused on the formulation of strategies to reduce the risks of 

disasters worldwide caused by the occurrence of earthquakes, tsunamis, and volcanic 

eruptions. The workshop was attended by 152 participants from 12 countries and 

regions representing 56 national and international institutes. The participants were 

encouraged by some successful risk mitigation activities and progress of some local 

and global risk reduction efforts. Collaboration between geohazard institutes and 

organizations in the Asia-Pacific region can advance the science of natural hazards 

and contribute to the reduction of the loss of lives and properties caused by the 

occurrence of earthquakes, tsunamis, and volcanic eruptions.

During the workshop, the G-EVER1 accord was approved by the participants. 

The Accord consists of 10 recommendations: 

・ Establish a consortium of Asia-Pacific geohazard research institutes, with the 

goal of enhancing collaboration, sharing resources, and making information 

about risk from earthquakes and volcanic eruptions freely available and 

understandable.

・ Promote the use of hazard information in decision-making by citizens, 

governments, and businesses, so our science supports mitigation actions.

・ Develop a website hub for the consortium in English and major Asian languages, 

which would link to websites of allied global efforts, such as VHub, GEM 

Nexus, and the International Seismological Centre (ISC).

・ Establish or endorse data interchange standards and standardized analytical 

methods for geohazard institutes of the world to promote data sharing and 

comparative analyses.

・ Actively participate in related global risk reduction efforts, such as Integrated 

Research on Disaster Risk (IRDR) Program, Global Earthquake Model (GEM), 

Global Volcanic Model (GVM) and their component databases like World 

Organization of Volcano Observatories Database (WOVOdat) and GEM Faulted 

Earth.

・ Promote "the borderless world of science" with trans-border hazard maps built 

using common data sets, and more uniform and advanced methods and software 

than has been possible in the past.

・ Promote exchange visits among researchers of the consortium, and encourage 

opportunities for graduate study in geohazards.

・ Encourage the formation of working groups for broad, multi-disciplinary, 

unifying themes.Promote best practice training on interaction with the media, on 

outreach to citizens and school children on hazard preparedness, and on 

72
interaction between volcano scientists and Volcanic Ash Advisory Centres in the 

region.

・ Convene a G-EVER workshop every 2 years in Asia-Pacific countries in 

conjunction with major regional events (such as AOGS, WPGM and AGU 

meetings).

 The G-EVER Hub website ( http://g-ever.org ) was established to promote the

exchange of information and knowledge among the Asia-Pacific countries. Several 

G-EVER working groups and task forces were proposed such as: (1) large-scale 

earthquake risk assessment, (2) large-scale volcanic eruption risk assessment, (3) 

next-generation real-time volcano hazard assessment, and (4) Asia-Pacific region 

earthquake and volcano hazard mapping. Establishing or endorsing data interchange 

standards and standardized analytical methods for geohazard institutes of the world to 

promote data sharing and comparative analyses were also considered important 

target. 

Group photo at the G-ever1 workshop held in Tsukuba on Feb. 22-24, 2012 

73
Session VIII

Abstracts 

74
Dynamics of Migrating Earthquake Swarms at Yellowstone and Mount Rainier 

Volcanic Areas: Evidence for Fluid Triggering? 

David R. Shelly, Seth C. Moran, David P. Hill, Frédérick Massin, Jamie Farrell, Robert 

B. Smith 

Volcanic and hydrothermal regions often exhibit high rates of seismicity and 

frequent seismic swarms. Two recent examples include a swarm September 20-23, 

2009, beneath Mount Rainier and a January 15-February 6, 2010 swarm near the 

northwest rim of Yellowstone Caldera (Madison Plateau) in Yellowstone National 

Park. To help illuminate the underlying processes driving the activity, we attempt 

to identify low signal-to-noise earthquakes and to locate them precisely along with 

numerous cataloged events. 

For each swarm, we use the waveforms of cataloged events to scan the continuous 

seismic data, with the goal of improving both event identification and relative 

locations. To do this, we measure both the height and precise timing of the 

correlation peaks between catalog events and the continuous waveform data. We 

then input the resulting differential times to a double-difference relative relocation 

algorithm. This results in successful location of a factor of ~4 more events than 

included in the catalog, or roughly 800 and 8000 events for the Rainier and 

Yellowstone sequences, respectively. 

Despite differences in the depth range (2-3.5 km below mean station elevation at 

Rainier versus 6-11 km in Yellowstone), the swarms share many common 

characteristics. Both seismic swarms exhibit clear migration of event centroids, and 

in each case activity expands systematically outward in a largely planar pattern with 

time. Expansion of the seismicity front is episodic and seems to be led by smaller 

events, even when accounting for differences in source dimensions. Both the 

Rainier and Yellowstone swarms activate shallower, seismically disconnected 

structures later in the swarm evolution. A further similarity is that dominant 

structures, as defined by the earthquake locations, strike perpendicular to the 

direction of minimum regional compressive stress, and neither nodal plane of 

double-couple-constrained focal mechanisms generally matches the trend of event 

locations. This suggests the possibility of en echelon faulting and/or a component of 

fault opening, perhaps in a fracture mesh geometry similar to that envisioned by Hill 

[1977]. We hypothesize that both swarms were driven by sudden fluid pressure 

increases diffusing through the crust along pre-existing fractures, in combination 

with stress transfer from preceding events. If so, these swarms may represent 

natural analogs for seismicity induced by industrial injection. 

75
Detection of short-term slow slip events 

along the Nankai trough, southwest Japan using GNSS data

Takuya Nishimura1, Takanori Matsuzawa2, and Kazushige Obara3

1Geospatial Information Authority of Japan 

2National Research Institute for Earth Science and Disaster Prevention 

3

Earthquake Research Institute, University of Tokyo 

t_nisimura@gsi.go.jp 

Short-term slow slip events (SSEs) along the Nankai trough, southwestern Japan have been 

observed only by tiltmeters and strainmeters. Here, we present a method to detect the deformation 

associated with the SSEs and fault models of the SSEs on the plate interface of the Philippine Sea 

plate inverted from GNSS data. We also compare them with a tremor activity (Maeda and Obara, 

2009; Obara et al., 2010) and the fault models of the SSEs estimated from tilt data (Sekine et al., 

2010). 

Daily coordinates of 565 GEONET stations in southwestern Japan were used to detect the 

deformation of the SSEs. We fitted a step function to the filtered daily coordinates to detect 

displacements in a direction of N130oE which is opposite to the relative plate motion between the 

Philippine Sea plate and southwestern Japan. The candidate dates of the SSEs are determined if the 

significant displacements were detected. And three components (i.e., EW, NS, and UD) of the 

displacement on the date were inverted to estimate a rectangular fault model (Fig. 1). We finally 

recognized SSEs if the observed displacement were well reproduced by the fault model. 

209 candidates of SSEs were found in a period from June 19, 1996 to January 7, 2012. They 

were categorized into 97 certain SSEs including 3 double-counted events, 63 possible SSEs and 49 

non-SSEs. Moment magnitude (Mw) of 157 “certain” and “possible” SSEs ranges between 5.5 and 

6.4. SSEs with Mw ≥ 6.2 have occurred only in western and central Shikoku 5 times. No certain 

SSEs (Fig. 2) occurred in the Kii Channel (around 135.0oE) and east of 137.5oE (Lake Hamana). A 

couple of certain SSEs have occurred in Ise Bay where the tremor activity is weak. 

Comparing the fault models from GNSS with those from tilt data (Sekine et al., 2010), we 

found 27 SSEs included in both catalogues. There is no systematic difference of their Mw estimated 

from GNSS and tilt. SSEs with Mw ≥ 6.1 were included in both catalogues. However, 25 and 17 

SSEs were detected solely from GNSS and tilt data, respectively. It, therefore, suggests that the 

detectability of neither GNSS nor tiltmeter is perfect for small SSEs. Space-time plot of the SSEs 

(Fig. 2) shows a variety of size and recurrence times, though it may be apparent due a lot of events 

missed by GNSS. However, we recognize that the number of the SSEs increases around 2004 in 

eastern Shikoku. The increase may reflect a long-term change of conditions on the plate interface 

76
because similar increase is also observed in tremor activities (Obara et al., 2010). 

Figure 1. Observed and calculated displacements for “certain” SSE along the Nankai trough, 

western Japan. Black and white vectors are observation and calculation using a rectangular fault 

model, respectively. Purple circles are epicenter of nonvolcanic tremors for 5 days centering the 

certain day. (a) An event on November 13, 2008. (b) An event on December 29, 2009. 

Figure 2. Space-time plot of the SSEs. Red and yellow rectangles show fault models of “certain” 

and “possible” SSEs, respectively. The horizontal axis indicates the date and the slip amount for 

each SSE. Blue and purple stars represent dates of the “certain” and “possible” SSEs, 

respectively. 

77
Mitigation of Earthquake Hazards with a Seismogeodetic Model as 

Demonstrated for the 2011 Mw 9.0 Tohoku-oki Earthquake 

Yehuda Bock (ybock@ucsd.edu), Brendan Crowell, Diego Melgar 

Institute of Geophysics and Planetary Physics 

Scripps Institution of Oceanography 

La Jolla, California 

Saturation of broadband seismometers in the near field and problems with the double integration 

of accelerometer data into displacements in real time degrade early warning and rapid source 

characterization for large earthquakes. An integrated seismogeodetic network model overcomes 

these limitations to estimate, on the fly, the full spectrum of seismic motions, allowing for an 

order of magnitude improvement in response time compared to traditional seismic methods as 

demonstrated for the 2011 Mw 9.0 Tohoku-oki earthquake in Japan. Replaying local data in a 

simulated real-time mode from 785 GPS GEONET stations and 190 accelerometers from the KNET and KiK-net networks, we demonstrate that an accurate centroid moment tensor solution to 

ascertain the type of earthquake, immediately followed by a finite fault slip model could have 

been obtained in about 3 minutes, providing more accurate and timely warnings of the severity of 

the impending tsunami and assisting first responders with evacuation and recovery efforts. We 

use the rapid slip inversion to model the ensuing tsunami. The seismogeodetic network model is 

sufficiently accurate to detect P wave arrivals in the near field for large events, leading to 

improved earthquake early warning (EEW) methodologies that predict the arrival and intensity 

of S waves. We are currently applying the seismogeodetic approach and the lessons learned from 

the Tohoku-oki earthquake to a NASA-supported earthquake early warning system for Western 

North America (http://sopac.ucsd.edu/projects/realtime/READI/). 

78
Short-term slow slip events in the Kii peninsula by joint analysis of the AIST 

borehole strainmeter array and the NIED Hi-net tiltmeter array 

Norio Matsumoto, Satoshi Itaba,Yuichi Kitagawa, and Naoji Koizumi 

(Geological Survey of Japan, AIST, n.matsumoto@aist.go.jp) 

Hisanori Kimura 

(National Research Institute for Earth Science and Disaster Prevention) 

Geological Survey of Japan, AIST has constructed fourteen observatories in and around 

expected focal zones of the Nankai and Tonankai earthquakes to monitor groundwater and 

borehole strain during 2006 - 2010. The 30, 200 and 600 m-depth wells are constructed in one 

observatory. The multi-component borehole strainmeter and borehole tiltmeter are installed at 

the bottom of either the 600 m-depth well or the 200-m depth well. The purposes of this 

observation array are i) detection of groundwater level and/or strain changes associated with the 

possible preseismic, co- and afterseismic crustal deformation, ii) precise mapping of Short-term 

slow slip events (SSEs). 

For the borehole strainmeter data, we applied in-situ calibration methods by using response of 

each strain gauge to the Earth tides (Gladwin and Hart, 1985; Roeloffs, 2010), because the

observed borehole strain data is different from the strain in the surrounding rocks which is 

caused by inclusion of host rocks, grout and housing of strainmeter. Then, the calibration matrix 

estimated by the tidal response is 

validated by using theoretical and 

observed strain produce by longperiod surface wave. 

Geological Survey of Japan, 

AIST and the National Research 

Institute for Earth Science and 

Disaster Prevention (NIED) 

started to exchange AIST 

borehole strainmeter data with the 

NIED Hi-net tiltmeter data on a 

real-time basis since 2011. Fault 

models of SSEs are estimated 

using data from both the AIST 

borehole strainmeter array and the 

NIED Hi-net tiltmeter array by 

grid search method. The mapping 

accuracy of the fault models of 

SSEs is improved by the joint 

analysis of AIST strainmeter and 

the NIED Hi-net tiltmeter data. 

Figure 1 Fault model of SSE occurred on June, 2011 estimated by AIST 

strainmeter/tiltmeter data (top left), fault model by using the NIED Hi-net 

tiltmeter data (top right) and fault model by using both AIST 

strainmeter/tiltmeter and Hi-net tiltmeter data (bottom) 

79
3D quasi-dynamic modeling of cycles of megathrust earthquakes along the 

Japan Trench subduction zone considering high-speed friction 

Bunichiro Shibazaki 

International Institute of Seismology and Earthquake Engineering, 

Building Research Institute, Tsukuba, Japan 

e-mail: bshiba@kenken.go.jp

We investigate the generation mechanism of the 2011 Tohoku-oki earthquake (M 9.0) by 

performing 3D quasi-dynamic modeling with high-speed friction. Many studies on this 

earthquake indicate that large slips occurred near the trench off Miyagi and off Fukushima [e.g. 

Fujii et al., 2011; Satake et al., 2012] and that significant stress drop occurred in this region [e.g. 

Hasegawa et al., 2011]. These observational studies suggested that the 2011 Tohoku-oki 

earthquake released roughly all of the accumulated elastic strain on the plate interface owing to 

considerable weakening of the fault. Recent studies on high-speed friction show that considerable 

weakening can occur at a high slip velocity because of thermal pressurization or thermal 

weakening processes [Noda and Lapusta, 2010; Di Toro et al., 2011, Tsutsumi et al., 2011]. 

Based on experimental results by Tsutsumi et al. [2011], Shibazaki et al. [2011] propose a rateand state-dependent friction law with two state variables that exhibit weak velocity weakening or 

strengthening with a small critical displacement at low to intermediate velocities, but a velocity 

weakening with a large critical displacement at high slip velocities. We use this friction law for 

3D quasi-dynamic modeling of cycles of the Tohoku-oki earthquake and other large earthquakes 

along the Japan Trench subduction zone. We set several asperities where velocity weakening 

occurs at low to intermediate slip velocities. Outside of the asperities, velocity strengthening 

occurs at low to intermediate slip velocities. At high slip velocities, strong velocity weakening 

occurs both within and outside of the asperities. The rupture of asperities occurs at intervals of 

several tens of years, whereas megathrust events occur at much longer intervals (several hundred 

years). Megathrust slips occur even in regions where velocity strengthening occurs at low to 

intermediate slip velocities. Following M 9 class events, large afterslips occur in an area where 

the coseismic slip is not large, complementing the large coseismic slip zone. At points located in 

the velocity strengthening region at low slip velocity, even when coseismic slips occur, afterslips 

can occur as a result of velocity strengthening at low slip velocity. We also report the 

quasi-dynamic 3D model [Shibazaki et al., 2012] for the Tohoku-oki earthquake considering a 

rate- and state-dependent friction law and thermal pressurization by using a spectral solver [Noda 

and Lapusta, 2010] to efficiently calculate the temperature and pore-pressure evolution on a fault 

plane. 

80
Advantages and Limitations of Cluster Analysis in 

Interpreting Regional GPS Velocity Fields in California and Elsewhere 

Wayne Thatcher, James C. Savage, Robert W. Simpson 

Cluster analysis offers a simple, visual exploratory tool for the initial investigation of 

regional Global Positioning System (GPS) velocity observations, which are providing 

increasingly precise mappings of actively deforming continental lithosphere (Simpson et 

al., 2012 GRL). Here we describe new results applying cluster analysis to GPS velocities 

from three regions, the Mojave Desert and San Francisco Bay Area in California, and the 

Aegean in the eastern Mediterranean. Our goal is to illustrate the strengths and 

shortcomings of the method in searching for spatially coherent patterns of deformation 

including evidence for and against block-like behavior in these 3 regions. 

The deformation fields from dense regional GPS networks can often be concisely 

described in terms of relatively coherent blocks bounded by active faults, although the 

choice of blocks, their number and size, is subjective and usually guided by the 

distribution of known faults. Cluster analysis provides a completely objective method for 

identifying blocks ranging in size from 10s to 100s of km in characteristic dimension. 

Statistically significant clusters are almost invariably spatially compact, fault bounded, 

and define elastic blocks that deform significantly only on their boundaries. Often, higher 

order clusters that are not statistically significant are also spatially compact, suggesting 

the existence of additional blocks, or defining regions of other tectonic importance (e.g. 

zones of localized elastic strain accumulation near locked faults). These results can be 

used to both formulate tentative tectonic models with testable consequences and suggest 

focused new measurements in under-sampled regions. 

Cluster analysis has several noteworthy limitations. First of all, the method typically 

identifies only a small number of statistically significant clusters in a given region, 

usually 5 or less. Thus we often cannot preclude existence of more clusters that define 

smaller blocks, although this shortcoming can sometimes be overcome by applying the 

81
method to smaller sub-regions. Finally, GPS data precision and spatial density limits the 

degree to which distinct clusters can be defined, pointing to the importance higher 

precision (e.g. semi-continuous and continuous GPS sites) and incorporation of other data 

types like InSAR deformation maps into the method. 

82
Characteristic activity of tremor as proxy for slow slip in the transition zone 

along the subducting plate interface

Kazushige Obara1

, Takanori Matsuzawa2, Sachiko Tanaka2, and Takuto Maeda1

1

Earthquake Research Institute, The University of Tokyo, 

2

National Research Institute for Earth Science and Disaster Prevention

obara@eri.u-tokyo.ac.jp 

Non-volcanic tremor has been detected accompanied by slow slip event in subduction zone 

with young oceanic plate. Tremor is considered as a proxy for slow slip because duration of 

major tremor bursts measured seismologically in southwest Japan and Cascadia is proportional to 

the moment release of slow slip measured geodetically. Therefore, the activity style of tremor 

reflects occurrence and rupture process of slow slip. In this paper, we review characteristic 

activity of tremor to reveal the nature of slow slip along the subducting plate interface. 

Subduction tectonic tremor in southwest Japan and Cascadia is distributed within a narrow 

belt-like zone with a length of 600 and 1200 km along the strike of the slab, respectively. 

Along-strike segmentation of tremor is defined by coherent zones with different recurrence 

intervals and time offsets. The segmentation may be related to tectonics. In southwest Japan, 2 

large gaps, which reflect segment boundaries, correspond to the topographic highs of the 

subducting Philippine Sea plate due to its bending. Tremor episodes in both sides of Ise bay area, 

that is one of large gaps, usually occur independently; however, the migrating tremor in the Kii 

segment rarely continues to the Tokai segment beyond the gap. Similar migration of tremor 

activity is frequently observed between central and eastern Shikoku; there exists a small gap in 

tremor activity, less than 10 km in length horizontally. A tremor activity usually occurs along the

extrapolation from migration in another side of tremor cluster with a time difference of 1 or 2 

days. These continuity of tremor migration including a gap suggests that slow slip propagates 

through the inactive tremor zone.

Even though there is a possibility to exist aseismic slow slip propagation, tremor activity is a 

good proxy for slow slips within tremor zone, then we understand detail rupture process of slow 

slip from tremor migration. There are mainly three migration modes; along-strike long-term 

migration at a speed of about 10 km/day; rapid tremor reversal (RTR), which involves 

along-strike migration at speeds on the order of 100 km/day, propagating in the opposite direction 

to the long-term migration; and much faster slip-parallel migration at speeds on the order of 1000 

km/day. The improvement of tremor location method enabled to clarify the systematic along-dip 

variation in the activity style within the narrow tremor zone. The updip tremor activity is 

modulated by the major burst infrequently occurring at regular recurrence interval; however, the 

downdip tremor activity is composed of more frequent occurrence of minor burst. Major tremor 

burst, which was recognized as characterized by along-strike migration, usually starts from the 

83
downdip edge and migrates updip. That is to say, the long-term migration propagates radially. 

Recently, Obara et al. (2012) revealed the existence of along-strike migration with a speed of 

10–20 km/hr concentrated at the updip side of the tremor zone whereas the faster slip-parallel 

migration is distributed over the entire zone. The migration events include both of reverse and 

forward direction relative to the long-term migration. The reverse migration is considered as a 

seed of RTR. The long-term migration seems to consist of and be excited by the propagation of 

forward along-strike creep at the updip part. Systematic variation in recurrence and migration 

mode within the tremor zone must reflect the change in frictional property and fluid contents 

along the plate interface due to the temperature and material changes.

Figure Distribution of the migration direction of extracted 

migrating tremor sequences for two different time scales. Short 

lines on the map view indicate the migration direction plotted on the 

centroid location for its extracted migrating tremor sequence. The 

rose diagram at top left indicates the azimuthal distribution of the 

tremor migration in 15-degree bins. The diameter of the outer circle 

is normalized by the maximum number in each bin. Red color 

indicates the migration direction within the first or third quadrant, 

which is to the northeast or southwest along the strike of the slab, 

respectively. Blue color indicates a migration direction within the 

second or fourth quadrant, which is downdip or updip along the slip 

direction, respectively. The length of the time scale (T) is (a) 0.5, 

and (b) 2.0 hours. N is the total number of migrating tremor 

sequence for each time scale. Arrow indicates the relative plate 

motion [Miyazaki and Heki, 2001]. Dashed and chained lines 

indicate the directions of the average strike of the tremor zone and 

plate convergence, respectively. The pie chart at bottom right 

indicates the percentage of each migration direction during the 

background long-term migration episodes, showing clear 

propagation to the northeast or southwest. The term 

‘Perpendicular’ indicates a detected tremor sequence with a 

migration direction within the second or fourth quadrant. Other 

events composed of ‘Backward’ and ‘Forward’ have a migration direction within the first or third 

quadrant. The terms ‘Backward’ and ‘Forward’ indicate a detected tremor sequence migrating in the 

opposite or same direction to the direction of the long-term migration episode, respectively. The total 

number of detected tremor sequences within long-term migration episodes with clear propagation to the 

northeast or southwest is shown on the top of the circle. 

b

84
Repeating Earthquakes on the Parkfield Segment of the San Andreas: 

Do They Reload Themselves? 

Justin L. Rubinstein & William L. Ellsworth 

US Geological Survey – 345 Middlefield Road; Menlo Park, CA 94025 

Repeating earthquakes in the Parkfield segment of the San Andreas Fault are nearly 

periodic but deviate slightly in a manner that suggests more rapid reloading early in their cycle. 

We propose a self re-loading model where an asperity slips, causing creep in the surrounding 

volume. This creep, in turn, rapidly reloads the asperity, which is then further loaded at a tectonic 

rate. 

Repeating earthquakes in the Parkfield section of the San Andreas Fault exhibit slippredictable scaling, whereby moment increases with the preceding inter-event time. However, 

statistical analysis of these events indicates that while the repeaters exhibit a slip-predictable 

sense scaling, in a strict sense they are neither slip- nor time-predictable (Rubinstein et al., 2012). 

While the size of the repeating earthquakes does appear to scale linearly with inter-event time, 

this scaling predicts that at zero recurrence interval an earthquake would have non-zero size 

(incomplete stress drop). The slip-predictable model requires both a constant loading rate and a 

complete stress drop, hence it fails to explain our observations. 

As an alternative to the slip predictable model, we suggest that the reloading of the slip 

patch is nonlinear. In this model, the stressing rate on the fault patch increases immediately 

following an earthquake and decays with time to a constant background rate. This would give a 

rapidly increasing slip-budget immediately following an earthquake with the loading of the patch 

eventually slowing to a constant rate. We believe that our observations of the repeating events lie 

within this time period where the slip-deficit rate is constant, such that we see a linear 

relationship between slip and recurrence interval. The combination of the nonlinear loading and 

observations only during a period of constant loading would yield observations like ours, i.e. an 

apparent constant loading rate and incomplete stress drop. A nonlinear slip deficit rate and 

complete stress drop could come from two scenarios: 1) nonlinear loading rate of the fault patch 

from outside the fault patch, e.g., afterslip, or 2) a nonlinear increase in fault strength. 

To determine whether loading rate or fault strength can reproduce our observations we 

need to find an analogous situation where we know that the slip-deficit rate rapidly increases and 

decays back to a constant level. The aftershocks of the 2004 M 6.0 Parkfield Earthquake present 

this opportunity. Moment rates of the repeating earthquakes spiked immediately following the 

mainshock and decayed back to a constant level within 1-2 years, thus we can use these events to 

distinguish whether a variable loading rate or variable fault strength recovery can explain our 

observations. Analysis of the aftershocks indicates that a variable loading rate is the preferred 

model. The fault strength model would predict that fault strength will dramatically decrease at 

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the time of the mainshock, recovering with time. Monotonically increasing fault strength would 

allow for larger and larger earthquakes with increasing time since the mainshock. Our 

observations yield the opposite, where the repeating events get smaller with increasing time since 

the mainshock. Additionally, we prefer the variable loading rate model because we find that the 

moment rate of the repeating events matches the observed afterslip pattern. This would indicate 

that afterslip is driving the increased moment rate observed in the aftershocks. 

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Keynote Talks 

Abstracts 

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Earthquake loss modeling on a global scale: balancing empirical & physicsbased approaches 

 

David Wald, U.S. Geological Survey 

National Earthquake Information Center, Golden, CO 

The USGS Prompt Assessment of Global Earthquakes for Response (PAGER) system 

provides rapid and automated alerting of estimated economic and human impacts 

following earthquakes around the globe. Although PAGER's primary purpose is to 

quantitatively any earthquake's severity for situational awareness and response 

decision-making, the underlying tools developed are utilized for many other scientific 

and mitigation efforts. There are four components of the PAGER system. First, 

earthquakes trigger rapid source characterization; second, these source parameters 

inform our estimates of shaking-distribution (e.g., ShakeMap). Third, losses are then 

modeled by computed populations exposed per shaking intensity level, and countryspecific and shaking-dependent loss functions are used to provide estimates of 

economic impact and potential casualties. Finally, these uncertain loss estimates are 

communicated in an appropriate form for actionable decision-making among a variety 

of users. Rapidly and automatically assessing the wide range of seismological, 

demographic, building inventory, and vulnerability information necessary to make such 

loss estimates entails a requisite balance of empirical & physics-based modeling 

strategies. Several aspects of our problem cannot yet be adequately solved with purely 

empirical, nor solely mechanistic, approaches. The "physics-based" model components 

of the PAGER system are essential for informing empirical models where they are datalimited, and for providing a framework for better understanding the causative pathways 

that dominate earthquake losses around the globe. In the course of explaining the endto-end strategies and science/engineering employed by the PAGER system, I also 

describe what pragmatic choices were made in balancing the uncertainties in and 

benefits provided by our empirical, semi-empirical, expert-opinion, and physical models. 

Recognizing and reconciling the complimentary benefits of data-driven verses 

theoretical problem-solving is at the core of the PAGER system, as it is for a wide variety 

of other challenges within the earth sciences. 

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UNAVCO: Recent Earthquake Responses, Multi-hazard Networks, and 

Technology Development 

M. Meghan Miller, UNAVCO, Inc., 6350 Nautilus Drive, Boulder Colorado 80301 

UNAVCO, a non-profit university-governed consortium that facilitates geoscience 

research and education using geodesy, provides services to advance learning in response 

to significant earthquakes of interest to its science community. One hundred and four 

U.S. academic Members and 78 non-academic or international Associate Members 

share UNAVCO’s mission and community vision to transform human understanding of 

the changing Earth by enabling the integration of innovative technologies, open geodetic 

observations, and research, from pole to pole. The consortium operates a facility that 

provides engineering, data, and educational services to its investigator community, and 

the Plate Boundary Observatory, the geodetic component of the EarthScope Facility. 

UNAVCO resources include field engineering services; permanent, real-time/high rate, 

and campaign GPS deployment; new solutions for data communications and power 

systems; borehole tiltmeter, strainmeter, and seismometer deployments; ground-based 

LiDAR measurements and airborne LiDAR project management; InSAR data 

acquisition; assistance with education and outreach activities; data archiving and 

processing services; a messaging forum for coordination of communications among 

stakeholders, and hosting of an event website for posting of early results. 

Since 2011, UNAVCO has mounted a formal response to each of three events: the 23 

August 2011 Mw=5.8 Virginia earthquake, the 2011 March 11 Mw=9.0 Tohoku, Japan 

earthquake and tsunami, and the 2012 September 5 Mw=7.6 Nicoya Peninsula 

earthquake, Costa Rica. Initially developed for the 2008 Shake Out earthquake drill in 

southern California, UNAVCO’s organizational event response capabilities were tested 

and refined to ensure robust protocols for decision-making and geodetic observations in 

the wake of a natural disaster, with the goal of preparedness for rapid deployments 

when geodetic observations are required to strengthen geohazards science. 

For each of these earthquakes, a different UNAVCO staff member is appointed to serve 

as Event Response Coordinator, and manage communications, support requests, 

logistics and decision-making both within UNAVCO and the community at-large. The 

community activities, science contributions, and other resources are available at: 

http://www.unavco.org/support/event-response/event-response.html. These events 

have supported the science community in the collection of key data sets for the 

advancement of hazards science. 

In addition to these event-specific activities, UNAVCO has advanced two community 

multi-hazards GPS networks, in Africa (AfricaArray) and the Caribbean (COCONet). 

These provide an observational backbone to support a broad range of Earth and 

atmospheric science investigations with a focus on earthquake, sea level, and hurricane 

hazards. UNAVCO Development and Testing has furthered more robust remote BGAN 

communications for rapid deployments and has conducted shake table testing of various 

GPS antenna – receiver systems. 

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