bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multi-planar structures in the aftershock distribution of the Mid Niigata prefecture Earthquake in 2004
Authors: Aoki Shigeki , Nishi Masaki , Nakamura Koji , Hashimoto Tetsuo , Yoshikawa Sumio , Ito Hidemi M. 
Published: August 2014

AbstractA shallow destructive inland earthquake of M6.8 occurred on Oct. 23, 2004 (JST) in the middle part of Niigata prefecture, Japan. The aftershock activity was high as compared to those of the other shallow inland earthquakes in Japan. We relocated the sources of the main shock and aftershock activity by adopting the double-difference earthquake location algorithm. The precisely relocated hypocenter distribution shows that there are a doubleplanar structure with a distance 5 km in parallel dipping in WNW with about 50 degrees and a single-planar structure dipping in ESE with about 15 degrees. The upper and lower planes of the double plane began to be formed with the main shock and the largest aftershock of M6.5, respectively, while the ESE dipping plane began to be formed with the 3rd largest aftershock of M6.1. The three planes represent the fault planes of the large events mentioned above. The aftershock distribution is found to be a superposition of the fault planes of the main shock and the large aftershocks. The high aftershock activity is attributed to the formation of the fault planes.
Coseismic deformation of the Mid Niigata prefecture Earthquake in 2004 detected by RADARSAT/InSAR
Authors: Ozawa Taku , Nishimura Sou , Wada Yutaka , Ohkura Hiroshi 
Published: August 2014

Abstract
Crustal deformation associated with the Mid Niigata prefecture Earthquake in 2004 (MJMA = 6.8) was detected using RADARSAT SAR interferometry. A displacement of −40 cm in the line-of-sight to the satellite was observed to the west of the main shock epicenter, and a displacement of 20 cm was observed to the east of the epicenter. Fault parameters estimated from the obtained deformation were in good agreement with those of the Centroid Moment Tensor solution for the main shock provided by the Japan Meteorological Agency. In the postseismic period, a steep gradient of deformation was found around the Obiro and the Western Muikamachi Basin faults, indicating that a fault-slip occurred in the shallow part of the fault. Since the seismicity in the shallow part of the Western Muikamachi Basin fault was very low, we believe that it must have been an aseismic slip. Crustal deformation associated with an aftershock that occurred on October 27 (MJMA = 6.1) was detected, and it was ascertained that this aftershock had ruptured the conjugate plane with respect to the Obiro fault. Since locations and/or mechanisms of these faults differed significantly, it was determined that at least three faults were involved in this series of earthquakes.
Geologic fault model based on the high-resolution seismic reflection profile and aftershock distribution associated with the 2004 Mid-Niigata Prefecture earthquake (M6.8), central Japan
Authors: Kato Naoko , Echigo Tomoo , Sato Hiroshi , Tateishi Masaaki , Ogino Sumiko , Sakai Shin’ichi , Toda Shigeru , Koshiya Shin , Ito Tanio , Toyoshima Tsuyoshi , Imaizumi Toshifumi , Kato Hajime , Abe Shintaro 
Published: August 2014

AbstractThe Mid-Niigata Prefecture earthquake in 2004 (MJMA6.8) generated surface ruptures along the eastern rim of the Uonuma Hills. To elucidate the structural linkage between the surface ruptures and the source fault at depth, the high-resolution seismic reflection profile across the surface ruptures and nearby active faults, and the data of aftershock distribution are examined. The 5.2-km-long, high-resolution, depth-converted seismic section reveals an emergent thrust beneath the surface ruptures. A two-dimensional model of the fault geometry has been constructed based on the aftershock distribution and the shallow reflection profile. The development of the main geologic structure are well explained by forward modeling using a balanced cross-section method. In detail, the fault system generated the main shock dips at a steep angle (60°) below 5 km depth and more shallowly (30°) near the surface.
Relationship between geologic structure and the source fault of the 2004 Mid-Niigata Prefecture Earthquake, central Japan
Authors: Sato Hiroshi , Kato Naoko 
Published: August 2014

Abstract
The geologic structure of the Uonuma Hills, the site of the 2004 Mid-Niigata Prefecture Earthquake (MJMA 6.8), Japan, is examined based on published geologic maps, drill hole data and seismic reflection profiles. The Uonuma Hills are located in an active folding area on the eastern margin of the Niigata sedimentary basin, and are divided into three discrete regions from north to south based on the geologic structure. The southern extent is marked by a west-dipping homoclinal structure produced by reverse faulting of the west-dipping Muikamachi active fault. The central section exhibits a regional anticlinorium produced by west-dipping reverse faulting with a steep angle at depth (> 5 km) and a more shallow angle (30°) near the surface. This fault can be correlated with the source fault responsible for the main shock. The Muikamachi fault consists of two fault segments and the source faults of the northern and the southern segments show discrete geometry forming an step over. Thus, judging from the geologic structure, the 2004 Mid-Niigata Prefecture Earthquake ruptured to the maximum possible extent in this fault segment in the central part. Furthermore, this study reveals that the activity on the Muikamachi fault, which has an apparently continuous surface trace, is produced by two different source faults at depth, with important implications for seismic risk assessment.
Simulation of gigantic jets propagating from the top of thunderclouds to the ionosphere
Authors: Tong Lizhu , Nanbu Kenichi , Fukunishi Hiroshi 
Published: August 2014

Abstract
A randomly stepped leader propagation model is developed to study gigantic jets, a new type of lightning, connecting thunderclouds to the ionosphere. The thundercloud is considered as one electrode igniting gigantic jets and the ionosphere is assumed as the other. The propagation of stepped leader is considered as a field controlled random growth process. The electric field is produced due to the thundercloud charges and the self-consistently propagating leader. A leader propagation probability is proposed to determine whether the leader grows at the next step and what the step direction of the leader is in case of growth. The results show that leader propagation spans ~72 km from igniting position to the ionosphere. The simulation of leader propagation appears to be in agreement with the structure of observed gigantic jets.
The frequency variation of Pc5 ULF waves during a magnetic storm
Authors: Du A. , Sun W. , Xu W. , Gao X. 
Published: August 2014

Abstract
The relationship between Pc5 ULF waves and the asymmetric ring current during the magnetic storm on July 15, 2000 is studied using ground-based magnetometer data and particle observations by the LANL satellite. A frequency decreases of Pc5 is noted during the main phase, which can be attributed to injections of heavier ions (O+ and He+) into the ring current. In addition, it is observed that during the main phase of the storm, the frequency drop of the Pc5 in the IMAGE chain around the MLT midnight is larger than that in the ALASKA chain at MLT post noon. Meanwhile, the longitudinal variation ΔH with the maximum around midnight implies a highly asymmetric distribution of the ring current. These results suggested that the frequency variation of Pc5 pulsation during storms is related to the partial distribution in the ring current.
A predictive penetrative fracture mapping method from regional potential field and geologic datasets, southwest Colorado Plateau, U.S.A.
Authors: Gettings Mark E. , Bultman Mark W. 
Published: August 2014

Abstract
Some aquifers of the southwest Colorado Plateau, U.S.A., are deeply buried and overlain by several impermeable units, and thus recharge to the aquifer is probably mainly by seepage down penetrative fracture systems. This purpose of this study was to develop a method to map the location of candidate deep penetrative fractures over a 120,000 km2 area using gravity and aeromagnetic anomaly data together with surficial fracture data. The resulting database constitutes a spatially registered estimate of recharge location. Candidate deep fractures were obtained by spatial correlation of horizontal gradient and analytic signal maxima of gravity and magnetic anomalies vertically with major surficial lineaments obtained from geologic, topographic, side-looking airborne radar, and satellite imagery. The maps define a sub-set of possible penetrative fractures because of limitations of data coverage and the analysis technique. The data and techniques employed do not yield any indication as to whether fractures are open or closed. Correlations were carried out using image processing software in such a way that every pixel on the resulting grids was coded to uniquely identify which datasets correlated. The technique correctly identified known deep fracture systems and many new ones. Maps of the correlations also define in detail the tectonic fabrics of the southwestern Colorado Plateau.
Tectonic and magmatic patterns in the Jutulstraumen rift (?) region, East Antarctica, as imaged by high-resolution aeromagnetic data
Authors: Ferraccioli F. , Jones P. C. , Curtis M. L. , Leat P. T. , Riley T. R. 
Published: August 2014

Abstract
The Jutulstraumen ice stream in western Dronning Maud Land may conceal a Jurassic continental rift. Delineating the geometry and the magmatic patterns of this inferred glaciated rift in East Antarctica is important to improve our understanding of the regional tectonic and magmatic processes associated with Gondwana break-up. A high-resolution aeromagnetic survey provides new insights over the largely buried tectonic and magmatic patterns of the Jutulstraumen area. Prominent NE-SW oriented aeromagnetic trends are detected over the Jutulstraumen. These trends delineate major inherited structural boundaries, active in Grenvillian (about 1.1 Ga) and Pan-African times (about 500 Ma), which appear to strongly control the location of the later Jurassic rift. The postulated eastern flank of the rift is marked by a broad positive anomaly over H. U. Sverdrupfjella. Buried Grenvillian age rocks may be the source of the long-wavelength anomaly. However, the higher frequency components correlate with granitoids of late Pan-African age. The inferred western flank of the rift features short-wavelength anomalies over the Borgmassivet and Ahlmannryggen areas, indicating a considerably greater extent of mid-Proterozoic tholeiitic sills than apparent in outcrop. In contrast, aeromagnetic signatures suggest that alkaline plutons, which relate to Jurassic rifting, are restricted to outcrop areas along the eastern rift flank. The prominent magnetic low over the Jutulstraumen indicates either a largely amagmatic rift, or perhaps subglacial sediments within the rift basin.
Magnetic fabric and rock magnetic studies of metasedimentary rocks in the central Okcheon Metamorphic Belt, Korea
Authors: Park Yong-Hee , Doh Seong-Jae , Kim Wonnyon , Suk Dongwoo 
Published: August 2014

Abstract
Anisotropy of magnetic susceptibility (AMS) and rock magnetic studies have been carried out for the metasedimentary rocks in the central Okcheon Metamorphic Belt. The study area is divided into three metamorphic zones: the biotite zone, the garnet zone, and the sillimanite+andalusite zone from southeast to northwest. Magnetic foliation dipping to the northwest is the dominant magnetic fabric in the biotite zone. Magnetic lineation plunging down-dip of the vertical cleavage plane is appeared in the southeastern part of the garnet zone, while magnetic lineation plunging to southeast prevails in the middle and northwestern parts of the garnet zone. It is interpreted that this apparent synform structure, defined by AMS fabric data, was formed by successive top-to-the-southeast vergent thrusting followed by back-steepening process during the regional metamorphism in the Late Paleozoic. In the sillimanite + andalusite zone, AMS fabric is clearly defined and may reflect a tectonic fabric, recorded during the thermal metamorphism in the middle Jurassic, despite the scarcity of rock fabric in the field. The spatial distribution of magnetic mineralogy, defined by the rock magnetic results, implies the 500°C isotherm at the boundary between the biotite and garnet zones, which is associated with the transformation of pyrrhotite into magnetite above 500°C under the oxidizing condition.
Short time-scale heating of the Earth’s mantle by ice-sheet dynamics
Authors: Hanyk Ladislav , Matyska Ctirad , Yuen David A. 
Published: August 2014

Abstract
We have studied the possibility of short time-scale energy transfer from the ice sheet loading and unloading processes to the Earth’s interior via viscous dissipation associated with the transient viscoelastic flow in the mantle. We have focussed on the magnitude of glacially induced deformations and the corresponding shear heating for an ice sheet of the spatial extent of Laurentide region in Maxwellian viscoelastic compressible models with a Newtonian viscosity. We have used a discretization method based on the method of lines for integrating the time-dependent evolutionary equations of self-gravitational, viscoelastic flow. We have found that shear heating from the transient viscoelastic flow can represent a non-negligible mantle energy source with cryogenic origins. Volumetric heating by viscous deformation associated with these flows can be locally greater than chondritic heating by radioactivity. In the presence of an abrupt change in the ice loading history, the time average of the integral of the dissipation over depth corresponds to a mantle heat flow of the order of magnitude of mW/m2 below the periphery of ancient ice sheets or below their central areas. However, the peak values of this integral in time are almost two orders higher. Our results would suggest that some degree of volcanism may be associated with dramatic episodes in ice loading.
On the submarine communication cable JASC ground self-potential stability
Authors: Starjinsky Sergey S. , Nikiforov Valerian M. 
Published: August 2014

Abstract
This investigation was undertaken for searching the source of linear trends in JASC submarine cable data over the time interval of 6 years and estimating the electrode noise level. One of the reasons for a trend is probably the potential instability in the cable ground, which happened because the titanium electrodes of the ground were placed in sea water that is electrochemically active. To study this phenomenon, we have registered the voltage variations of three titanium JASC cable electrodes, which were closely spaced (≈15 cm) and placed at a depth of ≈15 m near the coast for 70 days, synchronously with JASC cable voltage observations. The electrode noise level and coherence between channels were estimated and linear trends in electrode pair voltage variation were revealed. The estimated linear trend magnitude is about 0.28 mV/day, which is comparable with 0.21 mV/day earlier observed in JASC submarine cable data. We concluded that the linear trend in JASC cable data is, at least partly, probably caused by the titanium electrodes potential variations. This linear trend should be registered simultaneously with JASC cable voltage observation, keeping in mind the possibility of finding a procedure for removing it, in order to enhance the signal/noise ratio in data.
Onshore-offshore seismic transect from the eastern Nankai Trough to central Japan crossing a zone of the Tokai slow slip event
Authors: Kodaira Shuichi , Iidaka Takashi , Nakanishi Ayako , Park Jin-Oh , Iwasaki Takaya , Kaneda Yoshiyuki 
Published: August 2014

Abstract
In the summer of 2001, an onshore-offshore integrated seismic survey was carried out along a 485 km long profile crossing the eastern Nankai Trough and central Japan from the western edge of the Izu island arc. Seismic velocity and reflectivity images showongoing subduction of repeated ridges. Two ridges are clearly resolved, the Paleo Zenisu-south ridge and -north ridge located between the Nankai Trough and central Japan. The two subducting ridges are 12 km thick by 40 km wide, and 20 km thick by 60 km wide, respectively. We propose that the north ridge may have prevented the eastward propagation of co-seismic slip during the 1944 earthquake due to strong coupling. Highly reflective subducting oceanic crust is imaged at 25–45 km depth beneath central Japan, and has a 2 km high dome structure at 30–40 km depth, indicating an even deeper ridge structure. This highly reflective subducted oceanic crust overlaps with the high Poisson’s ratio zone imaged in a seismic tomography study. From these relations, we propose that the Tokai silent slip can be attributed to a high pore pressure zone, which significantly extends the conditionally stable region at the top of the subducted crust.
Repeating short- and long-term slow slip events with deep tremor activity around the Bungo channel region, southwest Japan
Authors: Hirose Hitoshi , Obara Kazushige 
Published: August 2014

AbstractWe report the repeating occurrence of short- and long-term slow slip events (SSE) which are accompanied by deep tremor activity around the Bungo channel region, southwest Japan. Both of these activities are detected by NIED Hi-net, which is composed of densely distributed observatories equipped with a set of tiltmeter and a high-sensitivity seismograph. Since the short-term SSE is small in magnitude, GPS can detect only the long-term SSE. Some of these episodes have nearly the same surface deformation pattern. This shows the existence of ‘slow slip patches’ on a plate interface, where the episodic slow slip is the characteristic slip behavior. We observe a change in periodicity and size of the short-term episode after the onset of the long-term SSE. Moreover, the long-term slow slip accelerates when the short-term activity takes place. This suggests that there is an interaction between these two types of SSEs.
Triggering sequence of large aftershocks of the Mid Niigata prefecture, Japan Earthquake in 2004 by static stress changes
Authors: Miyazawa Masatoshi , Mori Jim , Iio Yoshihisa , Shibutani Takuo , Matsumoto Satoshi , Katao Hiroshi , Ohmi Shiro , Nishigami Kin’ya 
Published: August 2014

AbstractFollowing the Mid Niigata prefecture Earthquake (MJMA6.8) in 2004, 4 large aftershocks (MJMA6.3, 6.0, 6.5, 6.1) occurred: three within 40 minutes and one after 4 days. We examine the possibility for the triggering of this sequence of large aftershocks by static stress changes. For the close spatial triggering, it is important to have information about the fault geometries, slip distribution, and focal mechanisms. We determine the fault plane orientations from the aftershock distributions. Slip distributions of the mainshock and the largest aftershock are obtained by seismic waveform inversions of local strong-motion records. Mechanisms for the events are taken from MT solutions. The temporal variations of Coulomb failure function changes (Δ CFF) are calculated on the fault planes of the aftershocks before their rupture. Positive Δ CFF values (0.06–0.3 MPa) are obtained around the hypocenters on the fault planes, indicating the possibility that static triggering from the main event and following aftershocks can explain the occurrence of subsequent aftershocks.
A tectonic interpretation of NW-SE strike-slip faulting during the 2004 off the Kii peninsula earthquakes, Japan: Probable tear of the Philippine Sea plate
Authors: Miyoshi Takayuki , Ishibashi Katsuhiko 
Published: August 2014

Abstract
The 2004 off the Kii peninsula earthquakes (M
w 7.5 for the main shock) occurred within the subducting Philippine Sea (PHS) plate near its boundary, the Nankai trough, southwest Japan. The rupture mode of the foreshock-main shock-aftershock sequence was complicated, a combination of ENE-WSW striking (almost trough parallel) reverse faulting beneath the trough and NW-SE trending (almost trough normal) strike-slip faulting mostly on the landward side of the former. In this paper, we discuss the tectonic meaning of this NW-SE running strike-slip fault. We examined hypocenter distribution and focal mechanisms of slab earthquakes from October 1997 through September 2004 and confirmed a NW-SE striking tear of the PHS slab beneath the middle part of the Kii Peninsula pointed out by Miyoshi and Ishibashi (2004). According to the Earthquake Research Committee (2004) there is a NW-SE trending structural discontinuity in the PHS crust to the southeast of the main shock epicenter. Putting all features together, we interpret that there is a NW-SE striking fracture within the PHS plate continuously from the Nankai trough region to the slab beneath the Kii Peninsula, and that a partial rupture of this fracture occurred during the off the Kii peninsula earthquakes together with trough-parallel reverse faulting. It should be noted that two disastrous M 7-class slab earthquakes seem to have occurred along this tear beneath the peninsula in 1899 and 1952.
Mass and moment of inertia constraints on the lunar crustal thickness: Relations between crustal density, mantle density, and the reference radius of the crust-mantle boundary
Authors: Hikida Hajime , Mizutani Hitoshi 
Published: August 2014

Abstract
The gravity inversion for the lunar crustal thickness needs three parameters: the crustal density, mantle density, and the reference radius of the crust-mantle boundary. The assumption of crust and mantle densities is found to significantly affect on the resultant crustal thickness variations. Moreover, the recent seismic analyses suggest the possibility of thinner crustal thickness around the Apollo 12 site than that proposed in the Apollo-era, on which the previous gravity inversions relied upon. Therefore the validity of the assumption used in previous gravity-inversion studies must be re-examined in detail. By using a simple three-layered mass model of the Moon including a uniform crust, mantle, and core, we determine possible combinations of the three parameters, satisfying the mass and moment of inertia constraints. The results show that the set of the parameters used in Neumann et al. (1996) can be consistent with mass and moment of inertia constraints, while those in Wieczorek and Phillips (1998) does not satisfy the constraints.
Candidate main-field models for producing the 9th generation IGRF
Authors: Mandea Mioara 
Published: August 2014

Abstract
This paper presents the various candidate models used in deriving the 9th generation IGRF. Based on notes submitted to the IAGA working group V-MOD with the Gauss coefficients, a brief description of the data used and the method of modelling for each of the candidate models is given. The six candidate models for epoch 1995.0 and the five for epoch 2000.0 are presented. Improvements gained by the new models are also discussed.
Magnetic field modelling from scalar-only data: Resolving the Backus effect with the equatorial electrojet
Authors: Holme R. , James M. A. , Lühr H. 
Published: August 2014

Abstract
It is well known that models of the global geomagnetic field constructed from only measurements of the field intensity suffer from large errors arising from the Backus or perpendicular error effect. Knowledge of the location of the magnetic dip equator is in principal sufficient to eliminate this error. We investigate constraining the location of the dip equator using observations of the equatorial electrojet in intensity measurements made from the CHAMP satellite. While the models generated are inferior compared with models obtained from oriented three-component vector data, they may be of sufficient quality to allow construction of future global geomagnetic reference models in the absence of vector data.