Kurile Arc Subduction Zone: View of Great Earthquake Generation
and Disaster Mitigation of Related Phenomena

Editorial Board (September 2022)
Editor-in-Chief
Takeshi Sagiya, Nagoya University, Japan

Vice Editors-in-Chief
Masahito Nosé, Nagoya University, Japan

Aitaro Kato, University of Tokyo, Japan

Editors
Koki Aizawa
Hideo Aochi
Pascal Audet
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Xiaowei ChenPeter Chi
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Mie Ichihara
Hidekatsu Jin
Art Jolly
Shunichi Kamata
Nobuki Kame
Katsuya Kaneko
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Kunihiro Keika
Kostas Konstantinou
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Juanjo Ledo
Koji Matsuo
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Atsuko Namiki
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Yohei Yukutake
Seiji Zenitani

Hiroo Kanamori
Jun'ichiro Kawaguchi
Takafumi Matsui
Hitoshi Mizutani

Yasuo Ogawa
Toshitaka Tsuda
Zhongliang Wu
Kiyoshi Yomogida

Advisory Board
Benjamin Fong Chao
Bernard Chouet
Yoshimori Honkura
Toshihiko Iyemori

Journal Scope
Earth, Planets and Space (EPS) is the official journal of Society of Geomagnetism and Earth, Planetary
and Space Sciences, The Seismological Society of Japan, The Volcanological Society of Japan, The
Geodetic Society of Japan, and The Japanese Society for Planetary Sciences.
EPS is a peer-reviewed, open-access journal published under SpringerOpen. It is an international journal
covering scientific articles in the entire field of earth and planetary sciences, particularly geomagnetism,aeronomy, space science, seismology, volcanology, geodesy, and planetary science. EPS also welcomesarticles in new and interdisciplinary subjects, and technical reports on instrumentation and software.
The journal was launched in 1998 and has since published over 4000 articles. All of them are available forfree on SpringerLink:
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Yours sincerely,
Prof. Takeshi Sagiya
Editor-in-Chief, Earth, Planets and Space
eic@earth-planets-space.org

Earth, Planets and Space(2021) 73:122
Tanioka et al. Earth, Planets and Space
https://doi.org/10.1186/s40623-021-01439-8

Open Access

PREFACESpecial issue, “Kurile arc subduction
zone: View of great earthquake generationand disaster mitigation of related phenomena”
Yuichiro Tanioka1*, Naoki Uchida2, Aditya Riadi Gusman3, Masanobu Shishikura4 and Takuya Nishimura5

Next, using precise micro-earthquake data, the stressfield due to the Kurile subduction can be studied. Maeda
et al. (2020) studied the spatiotemporal variation in stressfrom eastern Aomori to Tsugaru Strait using those data.
Their results indicated that those variations reflected theeffects of the upper-plate bending and the 2011 TohokuOki earthquake, and that the compressional stress causedby the Pacific plate was relatively weak. Using aftershock
data of the 2018 Eastern Iburi earthquake, Susukida et al.
(2018) studied the stress field in the aftershock area in thewestern boundary of the Hidaka Collision Zone. Theirresults showed that the reverse-fault-type stress field was
predominant in this area.
Finally, forecast of future earthquake activities and precise tsunami forecast are challenges for disaster mitigation. Katsumata and Nakatani (2021) tested the seismic
quiescence hypothesis through retrospective trials ofalarm-based earthquake prediction in the Kurile–Japansubduction zone. Their conclusion is that there is a reasonable chance that their tested quiescence will pass
the cross-validation test when more target earthquakes
become available in the near future. Kano et al. (2020)
developed an adjoint method assimilating GNSS timeseries data to optimize the frictional parameters that
control the slip behavior on the fault. They applied themethod to the observed GNSS time series for the first
15 days following the 2003 Tokachi-oki earthquake andfound that the optimized frictional parameters quantitatively predicted the postseismic GNSS time series.
Therefore, their data assimilation method is an effective evaluation method for assessing risks of subsequent
earthquakes and for monitoring the recovery process
of megathrust earthquakes. As a near-field tsunami

Various great earthquakes have occurred in the past
along the Kurile subduction zone where the Pacific platesubducts along the Kurile Trench. The Headquarters
for Earthquake Research Promotion, Japan, published along-term evaluation report on the occurrence of large
subduction earthquakes along the Kurile Trench (Headquarters of Earthquake Research Promotion 2018). They
reported that the probability of a giant earthquake witha magnitude exceeding Mw 8.8 along the Kurile trenchin 30 years is between 7 and 40%, as of 2021. Mitigationof disasters due to the giant earthquake along the Kurile
arc subduction zone has become one of urgent challenges
in Japan. This special issue covers various researches
concerning earthquake generation and postseismic processes, seismic wave attenuation, forecast of seismic
activities, and mitigation of tsunami disasters in andaround the subduction zone.
First, precise hypocenter estimation of micro-earthquakes along the Kurile subduction zone is a key tounderstand seismic activity and the stress field. Ichiyanagi et al. (2020) presented that the estimation errorof hypocenter along the Kurile trench was significantly
reduced using both Japanese and Russian data. In addition, Shiina et al. (2021) indicated that high-attenuation
zones in the backarc mantle wedge controlled propagations of high-frequency S-wave later phases in addition
to the scatterers in the forearc region.

*Correspondence: tanioka@sci.hokudai.ac.jp1
Institute of Seismology and Volcanology, Faculty of Science, Hokkaido
University, Sapporo 060‑0810, Japan
Full list of author information is available at the end of the article© The Author(s) 2021, corrected publication 2021. This article is licensed under a Creative Commons Attribution 4.0 International License,
which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit tothe original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images orother third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line
to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory
regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of thislicence, visit http://creativecommons.org/licenses/by/4.0/.

1

Kurile Arc Subduction Zone: View of Great Earthquake Generation and Disaster Mitigation of Related Phenomena
Tanioka et al. Earth, Planets and Space(2021) 73:122

Page 2 of 2

forecasting method, Tanioka (2020) developed a method
assimilating ocean-bottom pressure sensor network(S-net) without any information of earthquakes. The
method was numerically tested for two large underthrust fault models, a giant earthquake (Mw8.8) andthe Nemuro-oki earthquake (Mw8.0) models along the
Kurile arc subduction zone. The results indicated that themethod was applicable to the data at the S-net stations.
This special issue presents promising results for mitigation of disaster due to giant earthquakes along the Kurile
arc subduction zone although some of researches are still
primitive and also challenging. Continuation of studies isnecessary to mitigate disaster due to future giant earthquakes. Most of researches presented in this special issue
were supported by the Ministry of Education, Culture,
Sports, Science and Technology (MEXT) of Japan, under“The Second Earthquake and Volcano Hazards Observation and Research Program”.

References
Headquarters of Earthquake Research Promotion (2018). Evaluations of occur‑
rence potential of large earthquakes along the Kurile trench. https://www.jishin.go.jp/main/chousa/kaikou_pdf/chishima3.pdf. Accessed 10
May 2021
Ichiyanagi M, Mikhaylov V, Kostylev D, Levin Y, Takahashi H (2020) Evaluation
for hypocenter estimation error in the southwestern Kuril trench using
Japan and Russia joint seismic data. Earth Planets Space 72:86. https://doi.org/10.1186/s40623‑020‑01215‑0
Kano M, Miyazaki S, Ishikawa Y, Hirahara K (2020) Adjoint‑based direct data
assimilation of GNSS time series for optimizing frictional parametersand predicting postseismic deformation following the 2003 Tokachi‑
oki earthquake. Earth Planets Space 72:159. https://doi.org/10.1186/
s40623‑020‑01293‑0
Katsumata K, Nakatani M (2021) Testing the seismic quiescence hypothesis
through retrospective trials of alarm‑based earthquake prediction in the
Kurile‑Japan subduction zone. Earth Planets Space 73:100. https://doi.
org/10.1186/s40623‑021‑01418‑z
Maeda S, Matsuzawa T, Okada T, Katao H, Yoshida T, Kosuga M, Otsubo M(2020) Spatiotemporal variations in the stress field in the northeastern‑
most part of the NE Japan arc: constraints from microearthquakes. Earth
Planets Space 72:117. https://doi.org/10.1186/s40623‑020‑01245‑8
Shiina T, Katsumata K, Yomogida K, Kato A (2021) Attenuation contrast in man‑tle wedge across the volcanic front of northeastern Japan that controls
propagations of high‑frequency S‑wave later phases. Earth Planets Space73:33. https://doi.org/10.1186/s40623‑021‑01361‑z
Susukida Y, Katsumata K, Ichiyanagi M, Ohzono M, Aoyama H, Tanaka R, Takada
M, Okada K, Takahashi H, Sakai S, Matsumoto S, Okada T, Matsuzawa T,
Hirano S, Yamanaka Y, Kosuga M, Katao H, Nagaoka A, Tsumura N, Ueno
T, The Group for the Aftershock Observations of the 2018 Hokkaido
Eastern Iburi Earthquake (2021) Focal mechanisms and the stress fieldin the aftershock area of 2018 the Hokkaido Eastern Iburi earthquake(MJMA = 6.7). Earth Planets Space 73:1. https://doi.org/10.1186/
s40623‑020‑01323‑x
Tanioka Y (2020) Improvement of near‑field tsunami forecasting method using
ocean‑bottom pressure sensor network (S‑net). Earth Planets Space72:132. https://doi.org/10.1186/s40623‑020‑01268‑1

Authors’ contributions
YT, NU, AG, MS, and TN served as guest editors for this special issue. All authors
read and approved the final manuscript.
Competing interests
The authors declare that they have no competing interests.
Author details
1
Institute of Seismology and Volcanology, Faculty of Science, Hokkaido Univer‑sity, Sapporo 060‑0810, Japan. 2 Research Center for Prediction of Earthquakes
and Volcanic Eruptions, Graduate School of Science, Tohoku University, Sen‑dai 980‑8578, Japan. 3 GNS Science, Lower Hutt 5040, New Zealand. 4 ResearchInstitute of Earthquake and Volcano Geology, Geological Survey of Japan,
National Institute of Advanced Industrial Science and Technology (AIST), 1‑1‑1
Higashi, Tsukuba, Ibaraki 305‑8567, Japan. 5 Research Center for Earthquake
Prediction, Disaster Prevention Research Institute, Kyoto University, Gokasho,Uji, Kyoto 611‑0011, Japan.

Publisher’s NoteSpringer Nature remains neutral with regard to jurisdictional claims in pub‑lished maps and institutional affiliations.

Received: 10 May 2021 Accepted: 11 May 2021

2

Earth, Planets and Space

FULL PAPER

Open Access

Improvement of near-field tsunami forecasting method
using ocean-bottom pressure sensor network (S-net)
Yuichiro Tanioka
Earth, Planets and Space 2020, 72:132 DOI: 10.1186/s40623-020-01268-1
Received: 23 June 2020, Accepted: 4 September 2020, Published: 14 September 2020

Abstract
Since the installation of a dense cabled observation network around the Japan Trench (S-net) by the Japanese government that includes 150
sensors, several tsunami forecasting methods that use the data collected from the ocean floor sensors were developed. One of such methods isthe tsunami forecasting method which assimilates the data without any information of earthquakes. The tsunami forecasting method based on
the assimilation of the ocean-bottom pressure data near the source area was developed by Tanioka in 2018. However, the method is too simple
to be used for an actual station distribution of S-net. To overcome its limitation, we developed an interpolation method to generate theappropriate data at the equally spaced positions for the assimilation from the data observed at sensors in S-net. The method was numericallytested for two large underthrust fault models, a giant earthquake (Mw8.8) and the Nemuro-oki earthquake (Mw8.0) models. Those fault models
off Hokkaido in Japan are expected to be ruptured in the future. The weighted interpolation method, in which weights of data are inversely
proportional to the square of the distance,
showed good results for the tsunami forecast
method with the data assimilation. Furthermore,
results indicated that the method is applicable tothe actual observed data at the S-net stations.
The only limitation of the weighted interpolation
method is that the computed tsunami
wavelengths tend to be longer than the actual
tsunamis wavelength.

Keywords: Tsunami forecasting method, Dataassimilation, Tsunami numericalsimulation, Kurile subduction
zone

Graphical abstract

Corresponding author: Yuichiro Tanioka, tanioka@sci.hokudai.ac.jp

FULL PAPER

Open Access

Adjoint-based direct data assimilation of GNSS time series for
optimizing frictional parameters and predicting postseismic
deformation following the 2003 Tokachi-oki earthquake
Masayuki Kano*, Shin’ichi Miyazaki, Yoichi Ishikawa and Kazuro Hirahara
Earth, Planets and Space 2020, 72:159 DOI: 10.1186/s40623-020-01293-0
Received: 29 June 2020, Accepted: 13 October 2020, Published: 22 October 2020

Abstract
Postseismic Global Navigation Satellite System (GNSS) time series followed by megathrust earthquakes can be interpreted as a result of afterslip
on the plate interface, especially in its early phase. Afterslip is a stress release process accumulated by adjacent coseismic slip and can beconsidered a recovery process for future events during earthquake cycles. Spatio-temporal evolution of afterslip often triggers subsequent
earthquakes through stress perturbation. Therefore, it is important to quantitatively capture the spatio-temporal evolution of afterslip andrelated postseismic crustal deformation and to predict their future evolution with a physics-based simulation. We developed an adjoint data
assimilation method, which directly assimilates GNSS time series into a physics-based model to optimize the frictional parameters that control
the slip behavior on the fault. The developed method was validated with synthetic data. Through the optimization of frictional parameters, thespatial distributions of afterslip could roughly (but not in detail) be reproduced if the observation noise was included. The optimization offrictional parameters reproduced not only the postseismic displacements used for the assimilation, but also improved the prediction skill of thefollowing time series. Then, we applied the developed method to the observed GNSS time series for the first 15 days following the 2003 Tokachioki earthquake. The frictional parameters in the afterslip regions were optimized to A–B ~ O(10 kPa), A ~ O(100 kPa), and L ~ O(10 mm). A large
afterslip is inferred on the shallower side of the coseismic slip area. The optimized
frictional parameters quantitatively predicted the postseismic GNSS time series forthe following 15 days. These characteristics can also be detected if the simulation
variables can be simultaneously optimized. The developed data assimilation
method, which can be directly applied to GNSS time series following megathrustearthquakes, is an effective quantitative evaluation method for assessing risks ofsubsequent earthquakes and for monitoring the recovery process of megathrustearthquakes.

Keywords: Data assimilation, Afterslip, The 2003 Tokachi-oki earthquake, GNSS,
Frictional parameters, Postseismic deformation prediction*Corresponding author: Masayuki Kano, masayuki.kano.a3@tohoku.ac.jp
3Graphical abstract

Kurile Arc Subduction Zone: View of Great Earthquake Generation and Disaster Mitigation of Related Phenomena

FULL PAPER

Open Access

Focal mechanisms and the stress field in the aftershock area ofthe 2018 Hokkaido Eastern Iburi earthquake (MJMA = 6.7)
Yuki Susukida, Kei Katsumata*, Masayoshi Ichiyanagi, Mako Ohzono, Hiroshi Aoyama, Ryo Tanaka, Masamitsu Takada,Teruhiro Yamaguchi, Kazumi Okada, Hiroaki Takahashi, Shin’ichi Sakai, Satoshi Matsumoto, Tomomi Okada,Toru Matsuzawa, Hiroki Miyamachi, Shuichiro Hirano, Yoshiko Yamanaka, Shinichiro Horikawa, Masahiro Kosuga,
Hiroshi Katao, Yoshihisa Iio, Airi Nagaoka, Noriko Tsumura, Tomotake Ueno and The Group for the Aftershock
Observations of the 2018 Hokkaido Eastern Iburi Earthquake
Earth, Planets and Space 2021, 73:1 DOI: 10.1186/s40623-020-01323-x
Received: 8 July 2020, Accepted: 25 November 2020, Published: 1 January 2021

Abstract

Depth (km)Depth (km)The tectonic stress field was investigated in and around the aftershock area of the Hokkaido Eastern Iburi earthquake (MJMA = 6.7) occurred on 6 September
2018. We deployed 26 temporary seismic stations in the aftershock area for approximately 2 months and located 1785 aftershocks precisely. Among theseaftershocks, 894 focal mechanism solutions were determined using the first-motion polarity of P wave from the temporary observation and the permanentseismic networks of Hokkaido University, Japan Meteorological Agency (JMA), and High Sensitivity Seismograph Network Japan (Hi-net). We found that (1) thereverse faulting and the strike-slip faulting are dominant in the aftershock area, (2) the average trend of P- and T-axes is 78° ± 33° and 352° ± 51°, respectively,and (3) the average plunge of P- and T-axes is 25° ± 16° and 44° ± 20°, respectively: the P-axis is close to be horizontal and the T-axis is more vertical than the
average of the P-axes. We applied a stress inversion method to the focal mechanism solutions to
LatitudeLatitude
42.6
42.8
42.6
42.8
estimate a stress field in the aftershock area. As a result, we found that the reverse fault type stress field00
is dominant in the aftershock area. An axis of the maximum principal stress (σ1) has the trend of 72° ± 7°
and the dipping eastward of 19° ± 4° and an axis of the intermediate principal stress (σ2) has the trend of
10
10131° ± 73° and the dipping southward of 10° ± 9°, indicating that both of σ1- and σ2-axes are close to be20
20
horizontal. An axis of the minimum principal stress (σ3) has the dipping westward of 67° ± 6° that is close
to be vertical. The results strongly suggest that the reverse-fault-type stress field is predominant as an
30
30
average over the aftershock area which is in the western boundary of the Hidaka Collision Zone. The
40
40
average of the stress ratio R = (σ1 − σ2)/(σ1 − σ3) is 0.61 ± 0.13 in the whole aftershock area. Although not
H:V=1:1
H:V=1:1
statistically significant, we suggest that R decreases systematically as the depth is getting deep, which is
50
50
modeled by a quadratic polynomial of depth.
50

Keywords: The Hokkaido Eastern Iburi earthquake, Reverse fault, Aftershock distribution,
Focal mechanism solution, Temporary seismic network, Stress inversionc0*Corresponding author: Kei Katsumata, kkatsu@sci.hokudai.ac.jp

7080
trend (°)

90

0

10
20
plunge (°)

Graphical abstractd

Latitude
42.6

42.8

30

Latitude

42.6

0

10

42.8

10
Depth (km)Depth (km)

FULL PAPER

60

20
30
40

Attenuation contrast in mantle wedge across the volcanic
front of northeastern Japan that controls propagations ofhigh-frequency S-wave later phases
H:V=1:1

50

240

270 300
trend (°)

330

20
30

Open Access

40
H:V=1:1

50
50

60
70
plunge (°)

Takahiro Shiina*, Kei Katsumata, Kiyoshi Yomogida and Aitaro Kato
Earth, Planets and Space 2021, 73:33 DOI: 10.1186/s40623-021-01361-z
Received: 4 July 2020, Accepted: 15 January 2021, Published: 2 February 2021

Abstract
Distinct later phases of waves with rich high-frequency (> 8 Hz) components were observed for intraslab earthquakes that
occurred at intermediate depths, particularly at depths exceeding 100 km, in the northeastern (NE) Japan subduction zone.
These high-frequency later phases (HFLPs) showed anomalously large peak-amplitude delays, up to ~ 50 s after direct S-wave
arrivals at stations in the backarc region. Using a source-scanning algorithm, we investigated the locations of passing points
affecting the propagation of HFLPs. The passing points were estimated to be in the forearc region in the entire NE Japan,
indicating that HFLPs are scattered waves that pass through athe forearc region. The propagating HFLPs seem to bypassb
the backarc mantle wedge, as a consequence of the distinct
attenuation contrast in the mantle wedge across the volcanic
front in NE Japan. These HFLP observations suggest that thehigh-attenuation zone in the backarc mantle wedge controls
propagations of the high-frequency waves of intraslab
earthquakes, in addition to the scatterers possibly locate in
the forearc region.

Keywords: High-frequency later phase, Intraslab

earthquake, Seismic wave scattering, S-wave
attenuation

Graphical abstract*Corresponding author: Takahiro Shiina, taka.shiina@aist.go.jp
480

Earth, Planets and Space

FULL PAPER

Open Access

Testing the seismic quiescence hypothesis throughretrospective trials of alarm-based earthquake predictionin the Kurile–Japan subduction zone
Kei Katsumata* and Masao Nakatani
Earth, Planets and Space 2021, 73:100 DOI: 10.1186/s40623-021-01418-z
Received: 5 October 2020, Accepted: 10 April 2021, Published: 27 April 2021

Abstractr: prediction rate

We make trial binary forecasts for the Kurile–Japan subduction zone for the period 1988–2014 by hypothesizing that seismic quiescence (i.e., theabsence of earthquakes of M ≥ 5 for a minimum period of Tq) is a precursor of a large (7.5 ≤ Mw < 8.5) earthquake in the coming period Ta within aradius R of the quiescence. We evaluate the receiver-operating-characteristic diagram constructed using a range of forecast models specified by(Tq, R, Ta). A forecast experiment targeting eight large earthquakes in the studied spacetime
suggests that the risk of a large earthquake is modestly (probability gain G ~ 2) but significantly(p-value less than 5%) heightened for several years following a long quiescent period of Tq ≥ 9years, within several tens of kilometers of the quiescence. We then attempt cross-validation,
1.0
where we use half the data for training [i.e., optimization of (Tq, R, Ta)] and the remaining half forevaluation. With only four target earthquakes available for evaluation of the forecasts in each of
the learning and evaluation periods, our forecast scheme did not pass the cross-validation test(with a criterion that the p-value is less than 5%). Hence, we cannot formally deny the possibility
that our positive results for the overall period are a ghost arising from over-fitting. However,
0.5
through detailed comparison of optimal models in the overall test with those in the crossvalidation tests, we argue that severe over-fitting is unlikely involved for the modest G of ~ 2
p−valueobtained in the overall test. There is thus a reasonable chance that the presently tested type of
0.00−0.05
0.05−0.10
quiescence will pass the cross-validation test when more target earthquakes become available
0.10−0.15
in the near future. In the meantime, we find that G improves to ~ 5 when target earthquakes are
0.15−1.00
limited to 8 ≤ Mw < 8.5, though we cannot say anything about the possible involvement of
0.0
over-fitting because we have only three such very large target earthquakes.

Keywords: Earthquake prediction, Seismic quiescence, Cross-validation, Kurile–Japan

0.0

subduction zone

0.5

1.0

f: alarm fraction

Graphical abstract*Corresponding author: Kei Katsumata, kkatsu@sci.hokudai.ac.jp

EXPRESS LETTER

Open Access

Spatiotemporal variations in the stress field in thenortheasternmost part of the NE Japan arc: constraints frommicroearthquakes
Sumire Maeda*, Toru Matsuzawa, Tomomi Okada, Hiroshi Katao, Takeyoshi Yoshida,
Masahiro Kosuga and Makoto Otsubo
Earth, Planets and Space 2020, 72:117 10.1186/s40623-020-01245-8
Received: 2 June 2020, Accepted: 31 July 2020, Published: 10 August 2020

Keywords: Focal mechanism, Stress field, Low-seismicity area, Microseismicity, Forearc,
Northeastern Japan, Pacific plate subduction, Kurile arc

region N, n = 17

Stress ratio, R

Frequency (%)

20
0

0.0

region C, n = 25

0.5Frequency (%)

60

20
0

region S, n = 28

0.5

:σ3-a

region N, n = 31

Stresregion C, n = 21

1.0

Stress ratio, R

60

20
0
1.0

Stres

0.0

40

0.5

:σ2-axis

0.0

40

0.0

:σ1-axis

1.0

Stress ratio, R

Graphical abstract

5

60
40

0.0

*Corresponding author: Sumire Maeda, maeda.sumire@aist.go.jpaFrequency (%):σ3-axis

Frequency (%)

We determined focal mechanism solutions of microearthquakes and examined the stress field in
the low-seismicity region from southern Hokkaido to eastern Aomori, NE Japan. The stress fields
determined in this study comprise (1) a reverse faulting stress regime in southern Hokkaido withthe axis of maximum compressional stress (σ1) being sub-horizontal and trending WNW–ESE, and(2) a stress regime in eastern Aomori to Tsugaru Strait that shows temporal variations anddifferential stress of less than tens of MPa. The spatiotemporal variation in stress from eastern
Aomori to Tsugaru Strait might reflect the effects of the upper-plate bending and the 2011 Mw 9.0
Tohoku-Oki earthquake. It also indicates that the compressional stress caused by the descending
Pacific plate is relatively weak, which is similar to other areas in eastern parts of the NE Japan arc.

:σ2-axis

Frequency (%):σ1-axis

region S, n = 38

Stres

Frequency (%)

Abstract

0.0

Kurile Arc Subduction Zone: View of Great Earthquake Generation and Disaster Mitigation of Related Phenomena

TECHNICAL REPORT

Open Access

Evaluation for hypocenter estimation error in the southwestern
Kuril trench using Japan and Russia joint seismic data
Masayoshi Ichiyanagi, Valentin Mikhaylov, Dmitry Kostylev, Yuri Levin and Hiroaki Takahashi*
Earth, Planets and Space 2020, 72:86 DOI: 10.1186/s40623-020-01215-0
Received: 8 April 2020, Accepted: 8 June 2020, Published: 16 June 2020

Abstract
The southwestern Kuril trench is seismically active due to the subduction of the Pacific plate. Great earthquakes in this zone havefrequently induced fatal disasters. Seismic monitoring and hypocenter catalogs provide fundamental information on earthquake
occurrence and disaster mitigation. Real-time hypocenter and magnitude estimates are extremely crucial data for tsunami
warning systems. However, this region is located in the international border zone between Japan and Russia. The Japan
Meteorological Agency and Russian Academy of Sciences have routinely determined hypocenters and issued earthquake
information independently. Waveform data have not yet been exchanged internationally in real time. Here, we evaluated how ahypothetical Japan–Russia joint seismic network could potentially improve the hypocenter estimation accuracy. Experiments
using numerical and observed data indicated that the joint
a single networkb joint network46˚
46˚
network extended the distance over which hypocenters can be
accurately determined over 100 km eastward compared to theJapan network only. This fact suggests that joint seismic data havethe potential to improve the hypocenter accuracy in this region,
44˚
44˚
which would provide improved performance in gathering disaster
information at the moment of a tsunami warning.
50 km

50 km

Keywords: The southwestern Kuril trench, Hypocenter

Depth(km)determination, Japan and Russia joint seismic
network, Great subduction earthquakes, Tsunami
warning

42˚
144˚
0

146˚

148˚

150˚

42˚
144˚
0

50

50

100

100

150

150

Graphical abstract*Corresponding author: Hiroaki Takahashi, hiroaki@sci.hokudai.ac.jp

6

146˚

148˚

150˚

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Contents
Special issue, “Kurile arc subduction zone: View of great earthquake generation and disaster mitigation of related
phenomena”...............................Yuichiro Tanioka, Naoki Uchida, Aditya Riadi Gusman, Masanobu Shishikura and Takuya Nishimura
Improvement of near-field tsunami forecasting method using ocean-bottom pressure sensor network (S-net)...........................................................................................................................................................................................................Yuichiro Tanioka
Adjoint-based direct data assimilation of GNSS time series for optimizing frictional parameters and predicting postseismic
deformation following the 2003 Tokachi-oki earthquake......................................................................................................... Masayuki Kano, Shin’ichi Miyazaki, Yoichi Ishikawa and Kazuro Hirahara
Focal mechanisms and the stress field in the aftershock area of the 2018 Hokkaido Eastern Iburi earthquake (MJMA = 6.7)............................. Yuki Susukida, Kei Katsumata, Masayoshi Ichiyanagi, Mako Ohzono, Hiroshi Aoyama, Ryo Tanaka, Masamitsu Takada,Teruhiro Yamaguchi, Kazumi Okada, Hiroaki Takahashi, Shin’ichi Sakai, Satoshi Matsumoto, Tomomi Okada,Toru Matsuzawa, Hiroki Miyamachi, Shuichiro Hirano, Yoshiko Yamanaka, Shinichiro Horikawa,
Masahiro Kosuga, Hiroshi Katao, Yoshihisa Iio, Airi Nagaoka, Noriko Tsumura, Tomotake Ueno
and The Group for the Aftershock Observations of the 2018 Hokkaido Eastern Iburi Earthquake

Attenuation contrast in mantle wedge across the volcanic front of northeastern Japan that controls propagations ofhigh-frequency S-wave later phases...........................................Takahiro Shiina, Kei Katsumata, Kiyoshi Yomogida and Aitaro Kato
Testing the seismic quiescence hypothesis through retrospective trials of alarm-based earthquake prediction in the
Kurile–Japan subduction zone............................................................................................................ Kei Katsumata and Masao Nakatani
Spatiotemporal variations in the stress field in the northeasternmost part of the NE Japan arc: constraints frommicroearthquakes...................................................................................Sumire Maeda, Toru Matsuzawa, Tomomi Okada, Hiroshi Katao,

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Takeyoshi Yoshida, Masahiro Kosuga and Makoto Otsubo

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Evaluation for hypocenter estimation error in the southwestern Kuril trench using Japan and Russia joint seismic data.................................................................... Masayoshi Ichiyanagi, Valentin Mikhaylov, Dmitry Kostylev, Yuri Levin and Hiroaki Takahashi

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Cover image: Kano, M. et al., Earth, Planets and Space 2020, 72:159 DOI: 10.1186/s40623-020-01293-0