bluuebunny/crossref_metadata_2025_split huggingface dataset:
Subsurface structural mapping of Gebel El-Zeit area, Gulf of Suez, Egypt using aeromagnetic data
Authors: Aboud Essam , Salem Ahmed , Ushijima Keisuke 
Published: August 2014

Abstract
The Gebel El-Zeit area is located on the western coast of the Gulf of Suez, Egypt. The areas in/and around the Gulf of Suez are generally important due to their hydrocarbon resources. In this study, we have applied gradient interpretation techniques (Euler deconvolution and analytic signal) to the aeromagnetic data of the Gebel El-Zeit area. The main objective of this study is to identify and delineate the possible subsurface structure of the area that may assist in locating new hydrocarbon prospects. Results of Euler method suggested that, on the eastern and western parts of the area, the basement could be observed on the ground (~50 m over the ground) and became more deeper on the central part to reach depth of 5 km (from the ground level). Results from the analytic signal method indicated that, the depth to the basement has an average value of 156 m on the eastern side and 758 m on the western side. Generally, the area is characterized by a graben structure bounded by major faults striking in the NW-SE direction.
Investigation of electron density profile in the lower ionosphere by SRP-4 rocket experiment
Authors: Ishisaka K. , Okada T. , Hawkins J. , Murakami S. , Miyake T. , Murayama Y. , Nagano I. , Matsumoto H. 
Published: August 2014

Abstract
The SRP-4 rocket was launched at 12:07 LT on 18 March 2002. The objective of this rocket experiment is the investigation of the electron density profile in the high-latitude D-region of the ionosphere at noon. The Low frequency and Medium frequency band radio Receiver (LMR) and the DC Probe System (DPS) were installed on-board the rocket to estimate the D-region electron density. The LMR measured the intensities of radio waves received from ground-based stations operating at 257 kHz, 660 kHz and 820 kHz, respectively. The DPS measured the electron current and the positive ion current using the biased electrodes. The electron density profile at altitudes below 90 km was estimated from the measured absorption of these radio waves. It was found that the electron density began to increase at the altitude of 52 km and was larger than that estimated by the International Reference Ionosphere model at altitudes from 74 km to 89 km.
Iberia-Azores Gravity Model (IAGRM) using multi-source gravity data
Authors: Catalao J. 
Published: August 2014

Abstract
A consistent high precision and high resolution gravity model in the north-east Atlantic off Iberia peninsula using multi-source gravity data, ship-borne and satellite derived gravity anomalies, is presented. A solution strategy based on least squares optimal interpolation was used to assimilate into a coherent gravity model, gravity data with different spectral and spatial resolutions. Satellite derived gravity anomalies from KMS02 model, with an error covariance of 25 mGal2, and marine data carefully edited and validated by bias crossover error adjustment, were used in this study. The observation error variance was determined from ship-borne track adjustment and assigned an independent value for each track determined from error variance propagation. Unbiased ship-borne gravity observations were assimilated into the satellite derived gravity KMS02 model by the least squares optimal interpolation algorithm (OI) with bias removed by applying a regional bias to all ship tracks (OI-b) and alternatively by constraining all ship tracks to KMS02 using bias and tilt (OI-t). External error of the model was determined by comparing with recent surveys and it was verified that OI-t approach improved the final gravity model to an accuracy of about 3 mGal. The effect of different merging approaches on geoid solution was also evaluated and it was verified that the merging process can contribute to improve the geoid accuracy up to 4 cm with the OI-t approach.
Atmospheric drag effects on the KOMPSAT-1 satellite during geomagnetic superstorms
Authors: Kim K.-H. , Moon Y.-J. , Cho K.-S. , Kim H.-D. , Park J.-Y. 
Published: August 2014

Abstract
We examine the atmospheric drag on the low earth-orbiting satellite, KOMPSAT-1 in a sun-synchronous orbit at ~685-km altitude starting in 1999, during a 3-month (October-December) period in 2003. This 3-month interval includes the October 29-30 and November 20 magnetic superstorms and weak to moderate storms. We observed that the daily KOMPSAT-1 drag acceleration transiently responses to transient storm-time disturbances. That is, there is an one-to-one correspondence between the KOMPSAT-1 drag accelerations and the storm events. We find that the drag acceleration correlates strongly with the level of geomagnetic disturbance. This indicates that the trajectory of KOMPSAT-1 is significantly perturbed during extremely disturbed intervals because of atmospheric density increase. The main contributor to the density increase is Joule heating associated with the geomagnetic activity rather than the solar EUV radiation, as reported by previous studies. We suggest that understanding how the upper atmosphere responses to the geomagnetic-associated heating is important to predict space weather impacts on low earth-orbiting satellites.
The seismicity, fault structures, and stress field in the seismic gap adjacent to the 2004 Mid-Niigata earthquake inferred from seismological observations
Authors: Imanishi Kazutoshi , Kuwahara Yasuto , Takeda Tetsuya , Haryu Yoshikatsu 
Published: August 2014

AbstractWe investigate the seismicity, fault structures, and stress field in the southern seismic gap adjacent to the source region of the 2004 Mid-Niigata earthquake based on precise earthquake locations and focal mechanism solutions. The double-difference earthquake locations reveal detailed fault structures including five discrete clusters. A stress tensor inversion method indicates that, at the southern ends of the Muikamachi and the Tokamachi faults, the stress state changes from thrust faulting to a strike-slip faulting regime. We show two possibilities for the deep-fault geometry of the southern part of the Muikamachi fault. Our preferred fault geometries of the Muikamachi fault differ from that of the mainshock, especially for the geometry of the dip direction. It is likely that the Muikamachi fault is divided into two segments whose boundary corresponds to the southern end of the source region of the 2004 event, and that the rupture area was terminated due to this fault segment boundary. The Coulomb failure stresses that are induced by the mainshock and the largest aftershock increase at the southern part of the Muikamachi faults. Furthermore, the angle between the maximum principal stress and the preferred fault planes implies that the shear stress resolving along the planes are large. This evidence suggests a high seismic risk in the seismic gap.
High-resolution aftershock observations in the source region of the 2004 mid-Niigata Prefecture Earthquake
Authors: Kato Aitaro ,   The Research Team of aftershock observations for the 2004 mid-Niigata Prefecture Earthquake
Published: August 2014

Abstract
We deployed an extremely dense temporal seismic network in the source region of the 2004 mid-Niigata Prefecture Earthquake (thrust fault) on October 23, 2004, Japan. The seismic network consisted of 145 temporary seismic stations within a 30 km squared and had been kept within approximately a month after the mainshock. High accurate hypocenters of 708 events were determined by inverting the arrival times using double-difference earthquake location algorithm. The aftershocks along the mainshock (M
w = 6.6) and the largest aftershock (M
w = 6.3) rupture zones are distributed on two 60° westward-dipping planes, located approximately 5 km apart. Conversely, the Oct. 27 aftershock (M
w = 5.8) occurred on an eastward dipping plane with a dip angle of 25° that was conjugate to the mainshock fault plane. Most of aftershocks at both northeastern and southwestern edges occurred at shallow depths with eastward-dipping planes. Epicenters of aftershocks in the southwestern region are aligned along N15°E, and rotate approximately 20° counterclockwise from the strike of the mainshock fault. This rotation of the aftershock alignments coincides with the rotation of anticline axes in the southwestern area of the source region. Furthermore, distributions of station corrections for a one-dimensional velocity model suggest that the seismic velocity at the western side of the Muikamachi-fault is lower than that at the eastern side. It is also inferred that the velocity structures in the hangingwall vary along the fault strike. The average velocity in the mainshock rupture area is higher than the periphery in the hangingwall, especially compared with the southwestern side of the hypocenter.
Source model of the 2005 Miyagi-Oki, Japan, earthquake estimated from broadband strong motions
Authors: Suzuki Wataru , Iwata Tomotaka 
Published: August 2014

AbstractWe estimate the source model of the 2005 Miyagi-Oki earthquake, which consists of two source patches called “strong motion generation areas (SMGAs)”, to explain the broadband strong motions. The location of the first SMGA is determined from the arrival time differences between the first motion and the first pulse in theP-wave portion. Based on the broadband waveform modeling obtained using the empirical Green’s function method, we estimate the parameters of the two SMGAs. The estimated location of the two SMGAs coincides with the two major large slip areas inferred from the inversion of strong-motion and teleseismic waveforms, which implies that the broadband strong motion of the 2005 Miyagi-Oki earthquake mainly radiates from the asperities. The deeper SMGA has a larger stress drop (34.1 MPa) than the shallower one (17.6 MPa). Comparison of the locations of SMGAs between the 2005 and 1978 Miyagi-Oki earthquakes suggests that they do not overlap with each other. The interplate earthquakes, including this event, were found to have smaller SMGAs than those predicted from the relationship of crustal earthquakes for a given seismic moment. This implies that the stress drop of the SMGAs for interplate earthquakes is larger than that for crustal earthquakes.
Day-to-day variability in the occurrence characteristics of Sq focus during d-months and its association with diurnal changes in the Declination component
Authors: Alex S. , Jadhav M. M. 
Published: August 2014

AbstractScrutiny of the geomagnetic observations of the Declination component “D” from equatorial and low-latitude locations in the Indian longitude revealed anomalous variations during d-months. Examination of the Quiet day (Ap≤7) variations in the Declination component (Yin nT =HsinD) and Horizontal component (H) during the d-months (November, December, January, February) of the low solar activity year 1977 revealed the salient features associated with the day-to-day changes observed in Sq current system over the latitude chain in the Indo-Russian longitude. Diurnal variations in the east-west componentYand north-south componentHwere used to depict the effect of changes in the Sq current pattern for a selected set of Quiet days, which are classified into normal and abnormal days based on the trend in the variation of the Declination component. Normal days designated in the study clearly showed the expected pattern of variation in ΔY(eastward-directed field) in the morning hours and westward-directed field in the afternoon hours, and diurnal variation of ΔHsimultaneously showed the presence of northern Sq focus within the low-latitude range. In contrast, the abnormal days projected by the variation in ΔYand ΔHon certain days of d-months showed an almost complete absence of the focus formation within the expected latitude extent. Day-to-day variability characteristics of the Declination component discussed in the study are illustrated in relation to modifications in the expected Sq current system by the invasion of the prevalent southern hemisphere current whorl to the northern hemisphere during the winter months. Some of the anomalous changes observed in the day-to-day variation in the latitudinal pattern of ΔYand ΔHcomponents are also interpreted as suggesting an influence of high-latitude magnetospheric current systems on certain quiet days.
Self-generation of phase coherence in parallel Alfvén turbulence
Authors: Nariyuki Y. , Hada T. 
Published: August 2014

Abstract
Nonlinear evolution of Alfvén turbulence is discussed within the framework of the derivative nonlinear Schroedinger equation (DNLS), a subset of the hall-MHD equation set, which includes quasi-parallel propagating right- and left-hand polarized Alfvén wave modes. By numerically time integrating the equation with periodic boundary conditions, we discuss relationship between generation of wave phase coherence and self-organization of the system due to birth of Alfvén solitons.
Co- and post-seismic slip associated with the 2005 Miyagi-oki earthquake (M7.2) as inferred from GPS data
Authors: Miura Satoshi , Iinuma Takeshi , Yui Satsoshi , Uchida Naoki , Sato Toshiya , Tachibana Kenji , Hasegawa Akira 
Published: August 2014

Abstract
A large earthquake with M7.2 occurred on August 16, 2005 along the plate boundary off Miyagi Prefecture. Co- and post-seismic deformations associated with this event were investigated to reveal the causal interplate slips using continuous GPS data and geodetic inversion. The coseismic slip distribution shows good agreement with that estimated by seismic waveform inversions. The major slip area is limited to the southeastern part of the rupture area of the previous 1978 event. The post-seismic slip extended to the southwest of the co-seismic slip area. These distinctive features of both the co- and post-seismic slips might be caused by the existence of the locked plate interface, where seismogenic stress has not released yet, in the northern part of the 1978 rupture area.
Revisiting the three M~7 Miyagi-oki earthquakes in the 1930s: possible seismogenic slip on asperities that were re-ruptured during the 1978 M=7.4 Miyagi-oki earthquake
Authors: Umino Norihito , Kono Toshio , Okada Tomomi , Nakajima Junichi , Matsuzawa Toru , Uchida Naoki , Hasegawa Akira , Tamura Yoshiaki , Aoki Gen 
Published: August 2014

Abstract
Hypocenters of main shocks and aftershocks of the 1933 M=7.1, 1936 M=7.4, 1937 M=7.1 and 1978 M=7.4 Miyagi-oki earthquakes are relocated using S-P times reported in the Seismological Bulletin of the Japan Meteorological Agency (JMA) and those re-read from original smoked-paper seismograms observed at the Mizusawa station of the National Astronomical Observatory of Japan (NAOJ) and the Mukaiyama station of Tohoku University. In order to reduce the error caused by inaccuracies of the arrival times and the small number of seismic observation stations, we determined the hypocenters by using a grid search method that assumed that the events occurred at the boundary between the subducting Pacific plate and the overriding plate. The main shock epicenters of these four earthquakes were determined to be close to each other, while the distributions of their aftershocks seem to disperse on the upper boundary of the Pacific plate. These distributions show that aftershock areas of the 1933, 1936 and 1937 events partly overlap with that of the 1978 event and occupy its easternmost, central and westernmost portions, respectively. This result suggests that the 1933, 1936 and 1937 events possibly ruptured a part of the source area of the 1978 event, i.e., its eastern, central and western portions, respectively.
Aftershock seismicity and fault structure of the 2005 West Off Fukuoka Prefecture Earthquake (MJMA7.0) derived from urgent joint observations
Authors: Shimizu Hiroshi , Takahashi Hiroaki , Okada Tomomi , Kanazawa Toshihiko , Iio Yoshihisa , Miyamachi Hiroki , Matsushima Takeshi , Ichiyanagi Masayoshi , Uchida Naoki , Iwasaki Takaya , Katao Hiroshi , Goto Kazuhiko , Matsumoto Satoshi , Hirata Naoshi , Nakao Shigeru , Uehira Kenji , Shinohara Masanao , Yakiwara Hiroshi , Kame Nobuki , Urabe Taku , Matsuwo Norimichi , Yamada Tomoaki , Watanabe Atsushi , Nakahigashi Kazuo , Enescu Bogdan , Uchida Kazunari , Hashimoto Shin’ichi , Hirano Syuichiro , Yagi Takeo , Kohno Yuhki , Ueno Tomotake , Saito Masaki , Hori Mio 
Published: August 2014

Abstract
On March 20, 2005, a large M
JMA7.0 earthquake occurred in the offshore area, west of Fukuoka prefecture, northern Kyushu, Japan. A series of joint observations were carried out by teams from several universities in Japan with the aim of investigating the aftershock activity. Six online telemetered and 17 offline recording seismic stations were installed on land around the aftershock area immediately followed the occurrence of the mainshock. Because aftershocks were located mainly in offshore regions, we also installed 11 ocean bottom seismometers (OBSs) just above the aftershock region and its vicinity in order to obtain accurate locations of hypocenters. The OBS observation was carried out from March 27 to April 13, 2005. We further conducted temporary GPS observations in which ten GPS receivers were deployed around the aftershock region. The aftershocks were mainly aligned along an approximately 25-km-long NW-SE trend, and the hypocenters of the main aftershock region were distributed on a nearly vertical plane at depths of 2–16 km. The mainshock was located near the central part of the main aftershock region at a depth of approximately 10 km. The largest aftershock of M
JMA5.8 occurred near the southeastern edge of the main aftershock region, and the aftershock region subsequently extended about 5 km in the SE direction as defined by secondary aftershock activity. Enlargement of the aftershock region did not occur after the peak in aftershock activity, and the aftershock activity gradually declined. The distribution of hypocenters and seismogenic stress as defined by aftershocks suggest that the 2005 West Off Fukuoka Prefecture Earthquake occurred on the fault that is the NW extension of the Kego fault, which extends NW-SE through the Fukuoka metropolitan area, and that the largest aftershock occurred at the northwestern tip of the Kego fault.
Seismic moment of the 1891 Nobi, Japan, earthquake estimated from historical seismograms
Authors: Fukuyama Eiichi , Muramatu Ikuei , Mikumo Takeshi 
Published: August 2014

AbstractThe seismic moment of the 1891 Nobi, Japan, earthquake has been evaluated from the historical seismogram recorded at the Central Meteorological Observatory in Tokyo. For this purpose, synthetic seismograms from point and finite source models with various fault parameters have been calculated by a discrete wave-number method, incorporating the instrumental response of the Gray-Milne-Ewing seismograph, and then compared with the original records. Our estimate of the seismic moment (Mo) is 1.8×1020N m corresponding to a moment magnitude (Mw) 7.5. This is significantly smaller than the previous estimates from the distribution of damage, but is consistent with that inferred from geological field survey (Matsuda, 1974) of the surface faults.
The daily variations of the vertical (Z) element of the geomagnetic field around the coast of mainland Australia
Authors: Stening R. J. , Reztsova T. 
Published: August 2014

Abstract
Use is made of an array of magnetic stations spread across the Australian mainland to examine the daily variation of the vertical element Z of the magnetic field. On sections of the west and east coasts visual inspection of Z variations shows that they respond mainly to the onshore component of the horizontal field as predicted by Bennett and Lilley, though only south of about 22°S on the east coast and south of 20°S on the west coast. On the north and south coasts this “coast effect” is not clearly seen at periods corresponding to the daily variation, though it sometimes appears on shorter time scales. On the north and south coasts Z appears to be mainly controlled by the decrease with latitude of the overhead eastward ionospheric currents as measured by the latitude gradient in the northward field, X. By subtracting the vector Z variation at an inland station from Z at a coastal station, the anomalous coastal effect in Z is calculated at periods of 12 and 24 h. These data show that the coastal effect is not just related to the horizontal onshore component but that some phase change is also required. An increase with latitude of the overhead eastward currents is sometimes found in morning hours corresponding to the morning current system identified in earlier work.
A tectonic interpretation of the Marmara Sea, NW Turkey from geophysical data
Authors: Ates Abdullah , Bilim Funda , Buyuksarac Aydin , Bektas Özcan 
Published: August 2014

Abstract
Recent scientific investigations have revealed the deep structure and fault mechanisms in the Marmara Sea and surroundings. However, magnetic and gravity anomalies display interesting features which were not resolved in detail. In this paper, simple two-dimensional magnetic and gravity models are constructed utilizing parameters such as the density contrast and susceptibilities obtained from a borehole, seismic sections and field susceptibility measurements, respectively. The gravity model shows the existence of horst-like structures, as suggested previously. The top of the magnetic bodies in the Marmara Sea is close to the sea bottom. In general, these magnetic bodies are fault-related. The gravity model complies with the seismic base map, which was constructed previously. The magnetic anomalies of anomalous regions of the Cinarcik andWestern Basins demonstrate slight anticlockwise block rotations, while large anticlockwise block rotation is observed in the eastern extremity of the Marmara Sea. Geophysical data and modeling results suggest that the origin and evaluation of the Marmara Sea began with the possibility of emplacement of horst-like structures in the Central Ridge during the Palaeozoic or earlier followed by block rotations and intrusion of the magnetic material into the upper crust with sediment deposition and faulting. It can also be suggested that the horst-like structures in the central Marmara act to diffuse the propagation of the Northern Boundary Fault (NBF). This aspect is correlated with the focal mechanisms of the major earthquakes.
Fine fault structure of a moderate earthquake in the 2007 earthquake sequence of Northern Mie, Japan
Authors: Yukutake Yohei , Takeda Tetsuya , Obara Kazushige 
Published: August 2014

Abstract
A moderate crustal earthquake (M
j = 5.4) occurred in the northern part of Mie Prefecture, Central Japan, 2007. In order to clarify the fault structure of the main shock and its relation to the active faults, we estimated the precise hypocenter locations and focal mechanisms. For the relocation of the hypocenters, we used the differential time obtained by both manual picking and waveform cross-correlation analysis. The estimated detailed fault structure suggests that the main shock ruptured the southwestward dipping fault plane. We found that the faults of the moderate earthquake possessed complex fault segments. Around the largest aftershock hypocenter, a subsidiary fault plane parallel to the main shock fault was identified. This result suggests that the fault structure around the deep part of the active fault is complicated. The hypocenters of the foreshock and main shock were located in the offset part of the aftershock alignment, implying that they did not occur on the same fault plane. The Chisato Fault and Yokkaichi Fault were located around the upward extension of the aftershock alignment. The main shock probably occurred in the deep parts of these faults.