bluuebunny/crossref_metadata_2025_split huggingface dataset:
Scaling of characterized slip models for plate-boundary earthquakes
Authors: Murotani Satoko , Miyake Hiroe , Koketsu Kazuki 
Published: August 2014

AbstractWe characterized source rupture models with heterogeneous slip of plate-boundary earthquakes in the Japan region. The slip models are inferred from strong-motion, teleseismic, geodetic, or tsunami records. For the identification of asperities in the slip models, we found that the area of subfaults retrieved with slips of >1.5 times the total average slip provides a size approximately equivalent to the characterized asperity by Somervilleet al.(1999). We then carried out regression analyses of the size and slip for the rupture area and asperity. The obtained scaling relationship to the seismic moment indicates that rupture areaS, average slipD, and combined area of asperitiesSaare 1.4, 0.4, and 1.2 times larger, respectively, than those of crustal earthquakes. In contrast, the ratios of the size and slip between the asperities and rupture area (Sa/SandDa′/D) are the same for plateboundary earthquakes as for crustal earthquakes. The above analyses indicate that plate-boundary and crustal earthquakes share similar source characteristics.
Tsunami waveform inversion of the 2007 Bengkulu, southern Sumatra, earthquake
Authors: Fujii Yushiro , Satake Kenji 
Published: August 2014

Asbtract
We performed tsunami waveform inversions for the Bengkulu, southern Sumatra, earthquake on September 12, 2007 (M
w 8.4 by USGS). The tsunami was recorded at many tide gauge stations around the Indian Ocean and by a DART system in the deep ocean. The observed tsunami records indicate that the amplitudes were less than several tens of centimeters at most stations, around 1 m at Padang, the nearest station to the source, and a few centimeters at the DART station. For the tsunami waveform inversions, we adopted 20-, 15- and 10-subfault models. The tsunami waveforms computed from the estimated slip distributions explain the observed waveforms at most stations, regardless of the subfault model. We found that large slips were consistently estimated at the deeper part (>24 km) of the fault plane, located more than 100 km from the trench axis. The largest slips of 6–9 m were located about 100–200 km northwest of the epicenter. The deep slips may have contributed to the relatively small tsunami for its earthquake size. The total seismic moment is calculated as 4.7 × 1021 N m (M
w = 8.4) for the 10-subfault model, our preferred model from a comparison of tsunami waveforms at Cocos and the DART station.
Rupture process during the 2007 Noto Hanto earthquake (MJMA 6.9) and strong-motion simulation in the source region
Authors: Shiba Yoshiaki 
Published: August 2014

Abstract
The source rupture process during the 2007 Noto Hanto earthquake is inferred using a broadband waveform inversion technique based on the empirical Green’s function and the simulated annealing. The spatio-temporal distributions of the moment density and rise time on the fault are estimated from displacement motions in the frequency range from 0.1 to 2 Hz, and effective stress distribution is derived from the velocity motions in the frequency range up to 5 Hz. Results from the displacement inversion indicate that the seismic moment is mainly released from a single asperity with an area of 10 × 10 km2, and total moment release is estimated to be about 1.3 × 1019 N m. The velocity inversion shows that the high effective stress area distributes on and around the asperity, in particular at the deep periphery of it. The broadband strong motions determined using the conventional source model composed of only the moment distribution are compared with those calculated by considering both moment and effective stress separately. The fit between observed acceleration motions and synthetic ones from both source models are generally good in the frequency range up to 10 Hz, and no evident difference is recognized.
Rupture process of the 2007 Noto Hanto earthquake: waveform inversion using empirical Green’s function
Authors: Nozu Atsushi 
Published: August 2014

Abstract
A waveform inversion study was conducted to reveal the rupture process of the 2007 Noto Hanto, Japan, earthquake using near-source strong ground motion records. To avoid uncertainty in the subsurface structure in and around the source region when calculating Green’s functions, I used the aftershock records as empirical Green’s functions. To ensure that the path and the site effects are shared between the ground motions from the mainshock and those from aftershocks, the mainshock fault plane was divided into four domains, each of which was allocated to one of the aftershocks used as the empirical Green’s function events. The result of the inversion indicated that the rupture process included the break of two asperities. The first asperity, located close to the JMA hypocenter, was broken soon after the rupture started. This was followed by an extension of the rupture and the subsequent break of the second shallow asperity. The total moment of the mainshock was estimated to be 1.96E+19 N m, which is roughly consistent with the moment estimated by the F-net (1.36E+19 N m). Agreement between the observed and synthetic ground motions is quite satisfactory.
Observation of ground motions of aftershocks of the 2007 Noto Hanto earthquake in Monzenmachi, the Wajima city, for estimation of site amplification
Authors: Yamanaka Hiroaki , Motoki Kentaro , Yamada Nobuyuki , Sugawara Tatsuya , Mabuchi Yumi , Seo Kazuoh 
Published: August 2014

Abstract
Heavy damage occurred in Monzenmachi, the Wajima city, in the northern part of the Noto peninsula during the 2007 Noto Hanto earthquake with an M
j of 6.9. The area is located along a river and sandwiched by mountains at the northern and southern ends of a Quaternary narrow valley 1–2 km wide. The seismic intensity observed in the area was 6 upper during the main shock. In this study, we conducted observations of ground motions during aftershocks in Monzenmachi to understand local site effects in the vicinity of the seismic intensity station. We installed 11 accelerometers in three areas of Monzenmachi, Hashiride, Touge, and Kuroshima. In each area, three or five stations were chosen for a deployment of a linear array across the areas with heavy damage. The analysis was performed using aftershock records observed during events with M
j of 2.3–4.4. The spectral ratio of records from the station near the seismic intensity station to a reference station on Tertiary layers shows a dominant peak at a period of 1 s. We also found distinct peaks at periods of 0.4–0.7 s in the spectral ratios at the sites in the areas with heavy damage. In contrast, no dominant peaks were identified at the stations at the foot of the mountains. This clearly indicates that site amplification effects play an important role in defining the damage distribution in an area. Similar peaks were found in the H/V spectra of microtremors at the aftershock observation sites, though the peak amplitudes of the microtremor H/Vs are smaller than those of the S-wave spectral ratios.
Groundwater level changes related to the ground shaking of the Noto Hanto Earthquake in 2007
Authors: Itaba Satoshi , Koizumi Naoji , Matsumoto Norio , Takahashi Makoto , Sato Tsutomu , Ohtani Ryu , Kitagawa Yuichi , Kuwahara Yasuto , Sato Takashi , Ozawa Kunio 
Published: August 2014

AbstractThe Geological Survey of Japan, AIST has been monitoring groundwater using the observation network of about 40 stations in and around the Kinki and Tokai districts for earthquake prediction research. The Noto Hanto Earthquake in 2007 (MJMA6.9) occurred in the northwestern part of the Noto Hanto Peninsula, Japan on March 25, 2007. The epicentral distance to the nearest and furthest observation well is about 100 km and 400 km, respectively. Changes in groundwater level related to the Noto Hanto Earthquake were detected at many stations. Most of these were changes in the long-term trend and/or short-term oscillation; there were a few steplike changes. The coseismic static volumetric strain changes calculated from the fault model ranged between 10−9and 10−10at most of the observation stations. These changes were therefore considered to be groundwater changes caused by the ground shaking because groundwater level sensitivity to crustal volumetric strain is a few centimeters to 10−8strain at the most. We compared the coseismic groundwater level changes for the Noto Hanto Earthquake with those for five recent large earthquakes and obtained rough characteristics of the effect of the ground shaking on the groundwater level at each of the observation stations.
Groundwater changes associated with the 2004 Niigata-Chuetsu and 2007 Chuetsu-oki earthquakes
Authors: Itaba Satoshi , Koizumi Naoji , Toyoshima Tsuyoshi , Kaneko Masashi , Sekiya Kazuyoshi , Ozawa Kunio 
Published: August 2014

AbstractThe Geological Survey of Japan, AIST, has been monitoring groundwater in and around the Kinki and Tokai districts for earthquake prediction research. The Niigata Prefectural Office has also been observing groundwater for monitoring land subsidence in Niigata Prefecture. The 2004 Niigata-Chuetsu (MJMA6.8) and 2007 Chuetsuoki (MJMA6.8) earthquakes occurred in Niigata Prefecture, Japan, on October 23, 2004 and July 16, 2007, respectively. The two earthquakes have a similar magnitude, epicenter, and mechanism. At many of the observation wells, we detected changes in groundwater level or pressure related to the two earthquakes, but no clear precursory changes. At all of our observation wells in Niigata Prefecture, trend changes were observed after coseismic step-like changes for both of the earthquakes. At some of the stations in and around the Kinki and Tokai districts, coseismic trend changes and/or step-like changes were observed. The pattern of the changes were almost similar for the two earthquakes. Those changes were considered to be caused not by the static crustal deformation but by the ground shaking.
Long-baseline quasi-real time kinematic GPS data analysis for early tsunami warning
Authors: Daud Mohd Effendi , Sagiya Takeshi , Kimata Fumiaki , Kato Teruyuki 
Published: August 2014

Abstract
Real time monitoring of wave height in the ocean far from the coast can contribute to mitigation of a tsunami disaster. Here we demonstrate that early detection of a damaging tsunami can be achieved using a new long baseline kinematic GPS method, by tracking the anomalous changes in sea surface heights. The movement of a GPS buoy relative to a base station with a baseline length of 500 km has been monitored in quasi-real time mode, and the tsunami waves caused by the 5 September 2004 Off Kii Peninsula earthquake, Japan, have been successfully resolved. Based on the continuous analysis of GPS buoy data for 8 days, the average scattering of the low-pass filtered 1-Hz GPS buoy heights after tidal correction are about 3.4 cm and 1.2 cm for typhoon and calm weather, respectively. That is precise enough to detect tsunami waves with an amplitude of over 30 cm even under typhoon conditions. The long baseline can ensure an adequate evacuation time for people living on the coast.
Coseismic fault model of the 2008 Iwate-Miyagi Nairiku earthquake deduced by a dense GPS network
Authors: Ohta Yusaku , Ohzono Mako , Miura Satoshi , Iinuma Takeshi , Tachibana Kenji , Takatsuka Kota , Miyao Kayo , Sato Toshiya , Umino Norihito 
Published: August 2014

AbstractA large earthquake ofMj7.2 occurred on June 14, 2008, beneath the border between Iwate and Miyagi prefectures in northeastern Japan. We propose a simple rectangular fault model based on a dense GPS network, including continuous GPS sites run by four agencies, to describe the coseismic deformation. The coseismic displacements are estimated by kinematic PPP (precise point positioning) analysis. Near the hypocenter, colocated independent instruments (integrated accelerogram and kinematic PPP) measure the same large displacement caused by the mainshock. The fault model explains the observations well and reproduces the observed complex spatial pattern, especially around the northern part of the focal area, which is the focus of a debate on whether or not the coseismic slip occurred on the Dedana fault system. Our results show that no major slip on the Dedana fault system occurred. The estimated amount of moment release was equivalent toMw6.9, and the maximum slip reached 3.5 m on the southern sub-fault.
A paleointensity study on middle Miocene to Pliocene volcanic rocks from south-eastern Spain
Authors: Calvo-Rathert M. , Goguitchaichvili A. , Vegas-Tubía N. 
Published: August 2014

Abstract
Thirteen middle-Miocene to Pliocene volcanic sites, belonging to four different types of volcanism (calc-alkaline volcanism, potassic calc-alkaline and shoshonitic volcanism, lamproitic volcanism and basaltic alkaline volcanism), have been sampled in south-eastern Spain for paleointensity determinations. Rock-magnetic studies yield low-Ti titanomagnetite as the main carrier of remanence, showing also the presence of titanohematites in several cases. Analysis of hysteresis parameters indicates a PSD domain structure. Paleointensity determinations were performed with the Coe (1967) method. Of the 90 paleointensity determinations carried out, 29 provide successful determinations which fulfil selection criteria; most of these were in samples of lamproitic volcanism. Only four lamproitic sites out of the 13 studied ones yield reliable results. All have a similar age of approximately 7 M.y. Virtual dipole moments (VDM) of three of these display values between approximately 4·1022 A m2 and 8·1022 A m2, thus providing new paleointensity data for a time interval (between 4 and 8 M.a.), with a lack of Thellier-type paleointensity determinations. The fourth site shows a much lower paleointensity of 1.6·1022 A m2, and may correspond to a polarity transition, in accordance with its paleo-directional results.
Paleomagnetic and rock-magnetic study on volcanic units of the Valsequillo Basin: implications for early human occupation in central Mexico
Authors: Goguitchaichvili Avto , Pozzo Ana Lillian Martin-Del , Rocha-Fernandez Jose Luis , Urrutia-Fucugauchi Jaime , Soler-Arechalde Ana Maria 
Published: August 2014

Abstract
Alleged human and animal footprints were found within the upper bedding surfaces of the Xalnene volcanic ash layer that outcrops in the Valsequillo Basin, south of Puebla, Mexico (Gonzalez et al, 2005). The ash has been dated at 40 ka by optically stimulated luminescence analysis, thereby providing new evidence that America was colonized earlier than the Clovis culture (about 13.5 Ma). We carried out paleomagnetic and rock magnetic analysis on 18 Xalnene ash block and core samples collected at two distinct localities and 19 standard paleomagnetic cores belonging to nearby monogenetic volcanoes. Our data provide evidence that both the volcanic lava flow and Xalnene ash were emplaced during the Laschamp geomagnetic event spanning from about 45 to 39 ka.
Seismo-acoustic location method for small-magnitude surface explosions
Authors: Che Il-Young , Shin Jin Soo , Kang Ik Bum 
Published: August 2014

Abstract
The aims of this study were to develop an improved method using infrasound observations at multiple seismoacoustic arrays for locating small-magnitude surface explosions at regional distances and to apply the method to ground-truth blasting events for validation. The location method is based on a nonlinear grid search using the travel times and back azimuths of infrasonic signals generated from the surface explosions and on seismic parameters that are independently determined by routine seismic monitoring systems. Specifically, the method utilizes wind-corrected infrasonic azimuths in grid searching to constrain the grids according to nearness to feasibly real observations. Ground-truth events were recorded by a seismo-acoustic station temporarily operated inside an open-pit mine and then used to investigate the improvement by the location method. The method improved the locating of ground-truth events by approximately 50% compared to the seismic location results.
Properties of matrices included in the calculation of geomagnetically induced currents (GICs) in power systems and introduction of a test model for GIC computation algorithms
Authors: Pirjola Risto 
Published: August 2014

Abstract
“Geomagnetically induced currents” (GICs) in ground-based networks are a manifestation of space weather and a potential source of problems to the systems. Exact matrix equations, which are summarized in this paper, for calculating GICs in a power system were formulated in the 1980s. These equations are reformulated here to show how they lead to a direct relation between GICs and the horizontal geoelectric field. Properties of the matrices, which enable the derivation of physical features of the flow of the GICs in a power system, are considered in detail. A specific aim of this study was to show that the ratio of the GICs obtained at a station under two different geophysical situations is independent of the total earthing resistance at that particular station. The behavior of the elements of the transfer matrix between geovoltages and GICs confirms the earlier result that it is sufficient to make a calculation of a small grid around the site if the GIC values at one site are of interest. Using the developed technique, I have calculated the GICs of the old configuration of the Finnish 400-kV grid.
Coseismic displacements and slip distribution from GPS and leveling observations for the 2006 Peinan earthquake (Mw 6.1) in southeastern Taiwan
Authors: Chen Horng-Yue , Hsu Ya-Ju , Lee Jian-Cheng , Yu Shui-Beih , Kuo Long-Chen , Jiang Yen-Lin , Liu Chi-Ching , Tsai Chun-Shyong 
Published: August 2014

Abstract
Since 2001, we have set up a dense geodetic network with 52 campaign-mode GPS sites and seven continuously recording GPS stations as well as six leveling routes in the Taitung area, Taiwan. Our aim was to better characterize near-fault crustal deformation of active faults at the plate suture of the Philippine Sea plate and Eurasia in southeastern Taiwan. On 1 April 2006, a moderate shallow earthquake (Mw 6.1, depth 10.8 km) occurred within this network. This earthquake resulted from rupturing of a geologically unknown or suspected fault (called the Y fault) located underneath the eastern margin of the Central Range. After removing the impacts of secular motions and postseismic slip, we estimated the coseismic displacements of the Peinan earthquake from the GPS and leveling measurements before and after the main shock. Three deformation types with distinct slip behaviors were revealed in three different regions: (1) near the epicenter—around 45 mm movement in the S-SSW direction with +20 to −20 mm vertical motion, in the northern part of the Y fault; (2) south of the epicenter across the southern part of the Y fault—approximately 35 mm in a westward movement with −60 mm subsidence (footwall side) and 40 mm in a SSW movement with at least 50 mm uplift (hanging-wall side), in the southern part of the Y fault; (3) northeast away from the epicenter—about 10 mm in a northward displacement with +15 to −10 mm vertical motions, in the Longitudinal Valley and on the western flank of the Coastal Range. This unique coseismic deformation pattern sheds new light on the characteristics of the suture zone between the Eurasian and Philippine Sea plates at the southernmost Longitudinal Valley. We used GPS and leveling measurements to invert for the fault geometry and the coseismic slip distribution. The optimal modeled fault is an 80° west-dipping fault at a depth of 0.5–20 km. The highest slip of about 0.33 m is located to the south of the hypocenter at a depth of 9–16 km. The total geodetic moment in our optimal model is 2.3 × 1018 Nt-m, which is equivalent to an earthquake of M
w 6.2. The surface coseismic displacements as well as the inferred coseismic slip distribution indicate a drastic change of slip behaviors in the middle of the Y fault. The left-lateral slippage near the hypocenter turned dramatically to reverse faulting with left-lateral component as rupturing propagated to the southern portion of the fault, suggesting that a possible right-lateral faulting occurred that coseismically cross cut the northern middle Peinanshan massif in the Longitudinal Valley.
Estimation of scan-gap limits on phase delay connections in Delta VLBI observations based on the phase structure function at a short time period
Authors: Kondo Tetsuro , Hobiger Thomas , Sekido Mamoru , Ichikawa Ryuichi , Koyama Yasuhiro , Takaba Hiroshi 
Published: August 2014

Abstract
The maximum scan-gap length which connects phase delays from scan to scan over a gap is an important issue in Delta Very Long Baseline Interferometry (D-VLBI), and it is affected by delay fluctuations caused by the wet troposphere. It has recently become possible to obtain near real-time fringe phases by using an e-VLBI technique that realizes real-time VLBI by connecting stations through high-speed Internet. Such real-time VLBI raises the possibility of dynamic D-VLBI scheduling, which changes scan and gap length dynamically according to the weather condition of the date. We have investigated this possibility by using phase structure functions obtained from continuous VLBI observations at S- and X-bands for 1–2 h at the Kashima, Gifu, and Koganei stations (not real-time ones). Five VLBI sessions were conducted during this study between March and July 2006 under different weather conditions. At first a simple method was developed to evaluate phase connectivity from a phase structure function. A model was also proposed to estimate a phase-structure function at longer time periods from a short time period. Finally, an available gap length was estimated using the model. Our results show that it is possible to estimate an available scan gap length by using a structure function at a time period of 10 s. This suggests that it is possible to control scan length and gap length dynamically in order to achieve the best performance of D-VLBI observations.
Coronal loops, flare ribbons and aurora during slip-running
Authors: Schmieder Brigitte , Aulanier Guillaume , Démoulin Pascal , Pariat Etienne 
Published: August 2014

Abstract
Solar two ribbon flares are commonly explained by magnetic field reconnections in the low corona. During the reconnection energetic particles (electrons and protons) are accelerated from the reconnection site. These particles are following the magnetic field lines down to the chromosphere. As the plasma density is higher in these lower layers, there are collisions and emission of radiation. Thus bright ribbons are observed at both ends of flare loops. These ribbons are typically observed in Hα and in EUV with SoHO and TRACE. As the time is going, these ribbons are expanding away of each other. In most studied models, the reconnection site is a separator line, where two magnetic separatrices intersect. They define four distinct connectivity domains, across which the magnetic connectivity changes discontinuously. In this paper, we present a generalization of this model to 3D complex magnetic topologies where there are no null points, but quasi-separatrices layers instead. In that case, while the ribbons spread away during reconnection, we show that magnetic field lines can quickly slip along them. We propose that this new phenomenon could explain fast extension of Hα and TRACE 1600 Å ribbons, fast moving HXR footpoints along the ribbons as observed by RHESSI, and that it is observed in soft X rays with Hinode/XRT.