bluuebunny/crossref_metadata_2025_split huggingface dataset:
Radiated energy from the Noto Hanto, Japan, earthquake of March 25, 2007, and its aftershock
Authors: Izutani Yasuo 
Published: August 2014

Abstract
The Noto Hanto earthquake of March 25, 2007, is a shallow reverse-faulting event with M
w = 6.7. We analyze transverse component accelerograms of the main shock and an aftershock (M
w = 3.6) recorded at 10 strong motion observation stations. The hypocenter of the aftershock is located very close to that of the main shock and the epicentral distances of the stations are between 15 and 65 km. We calculate spectral ratio between records of the main shock and the aftershock in order to obtain source spectral ratio by empirically removing the effects of wave propagation path and surface layers at the stations. Thus obtained source spectral ratio is inconsistent with that expected for the self-similar omega-square source model assuming constant stress drop. Fitting omega-square source spectral ratio with variable corner frequency to the observed spectral ratio, the radiated energy and the corner frequency for the main shock and the aftershock are estimated. The radiated energy is 6.8 × 1014 J for the main shock and 6.7 × 109 J for the aftershock. The energy-to-moment ratios for the main shock and the aftershock are 5.0 × 10−5 and 2.1 × 10−5. This scale-dependence of the energy-to-moment ratio is similar to that obtained previously for shallow strike-slip earthquakes and reverse-faulting earthquakes in Japan. The relationship between the seismic moment, M
0, and the corner frequency, f
0, is M
0 ∝ f
0
−3.3±0.2
.
Constrained simultaneous algebraic reconstruction technique (C-SART) —a new and simple algorithm applied to ionospheric tomography
Authors: Hobiger Thomas , Kondo Tetsuro , Koyama Yasuhiro 
Published: August 2014

Abstract
A simple and relatively fast method (C-SART) is presented for tomographic reconstruction of the electron density distribution in the ionosphere using smooth fields. Since it does not use matrix algebra, it can be implemented in a low-level programming language, which speeds up applications significantly. Compared with traditional simultaneous algebraic reconstruction, this method facilitates both estimation of instrumental offsets and consideration of physical principles (expressed in the form of finite differences). Testing using a 2D scenario and an artificial data set showed that C-SART can be used for radio tomographic reconstruction of the electron density distribution in the ionosphere using data collected by global navigation satellite system ground receivers and low Earth orbiting satellites. Its convergence speed is significantly higher than that of classical SART, but it needs to be speeded up by a factor of 100 or more to enable it to be used for (near) real-time 3D tomographic reconstruction of the ionosphere.
Resolving static offsets from high-rate GPS data: the 2003 Tokachi-oki earthquake
Authors: Larson Kristine M. , Miyazaki Shin’ichi 
Published: August 2014

Abstract
The M
w 8.0 2003 Tokachi-oki earthquake offshore Hokkaido is the largest earthquake observed to date by a dense GPS network (GEONET). These GPS data are important both for resolving the geodetic signature of the earthquake itself and studies of postseismic deformation. Because GPS positions are generally estimated by averaging 24 hours of observations, it can be difficult to separate the effects of the earthquake and early postseismic deformation. In order to address this difficulty, a Kalman filtering methodology is developed that allows the estimation of the static offsets for the mainshock, its largest aftershock, and postseismic deformation in the first 24 hours. The static offsets computed for this study can be used for earthquake rupture studies while the early postseismic data can be used to evaluate frictional properties of the fault.
In-situ stress at the northern portion of the Chelungpu fault, Taiwan, estimated on boring cores recovered from a 2-km-deep hole of TCDP
Authors: Yabe Yasuo , Song Sheng-Rong , Wang Chien-Ying 
Published: August 2014

AbstractWe have investigated the depth variation in the stress state at the northern part of the Chelungpu fault, Taiwan, which slipped during the 1999 Chi-Chi earthquake (Mw7.6). In-situ stress around the fault was estimated based on the stress memory of rocks recovered from five depths (739–1316 m) of a 2-km-deep-hole. The borehole intersects a fault zone at a depth of 1111 m (FZ1111), which is the best candidate for the Chelungpu fault. Our main results are: (1) theSHmaxdirection is parallel to the slip for the Chi-Chi earthquake and agrees with those of the local, regional, or tectonic scales estimated from various stress indicators; (2) significant aspects of the stress field are identical to those of paleostress; (3) the horizontal differential stress was significantly reduced just above FZ1111, which may be attributable to the existence of a significantly deformable zone at this depth.
Initial observations of auroras by the multi-spectral auroral camera on board the Reimei satellite
Authors: Obuchi Yasuyuki , Sakanoi Takeshi , Yamazaki Atsushi , Ino Tomohiro , Okano Shoichi , Kasaba Yasumasa , Hirahara Masafumi , Kanai Yoshikazu , Takeyama Norihide 
Published: August 2014

Abstract
The small Japanese scientific satellite Reimei was launched successfully from Baikonur Space Center into a sun-synchronous (noon-midnight meridian) polar orbit at an altitude of ∼630 km on August 23, 2005. Auroral fine structure observations have been performed by the multi-spectral auroral camera (MAC) and electron/ion spectrum analyzers (ESA/ISA) on board Reimei. The MAC is a three channel camera system used to simultaneously observe the temporal dynamics of the auroral fine structure at the wavelengths of 428 nm (N2
+ 1NG), 558 nm (O), and 670 nm (N2 1PG). Since its successful launch, Reimei has been operated continuously and produced lots of unique data on the auroral fine structures with the MAC and ESA/ISA. The initial observation data from MAC has shown the temporal dynamics of auroral fine structure, such as the vortex street, appearing in the poleward edge of the auroral oval. The significant differences in the auroral shapes between the MAC channels suggest the existence of different emission processes. Further, the height profiles of the aurora and airglow are clearly seen in the image data in the limb direction. It is expected that the various mechanisms and dynamics of auroral fine structures can be investigated by analyzing the Reimei observation data.
Aftershock observation of the Noto Hanto earthquake in 2007 using ocean bottom seismometers
Authors: Yamada Tomoaki , Mochizuki Kimihiro , Shinohara Masanao , Kanazawa Toshihiko , Kuwano Asako , Nakahigashi Kazuo , Hino Ryota , Uehira Kenji , Yagi Takeo , Takeda Naoto , Hashimoto Shinichi 
Published: August 2014

Abstract
The Noto Hanto earthquake in 2007 (M
j 6.9) occurred on March 25, 2007 near the west coast of the Noto peninsula, Honshu, Japan. To study the aftershock activity under the sea, we deployed pop-up type ocean bottom seismometers (OBSs) from April 5 to May 8, 2007. We combined data from ten ocean bottom and four onshore seismic stations located around the rupture area of the earthquake and determined the preliminary distribution of the aftershocks. Most of the offshore aftershocks are located in a depth range between 2 and 10 km, and no earthquakes are observed in the lower crust. Hypocenters of deep events occurring at depths greater than 5 km are confined to an area northeastward from the largest aftershock in offshore region. Most of the aftershocks aligned along a high angle and southeast dipping plane, which is consistent with the geometry of the active faults revealed by previous seismic reflection surveys.
Magnetic properties and archeointensity determination on Pre-Columbian pottery from Chiapas, Mesoamerica
Authors: Morales Juan , Goguitchaichvili Avto , Acosta Guillermo , González-Moran Tomas , Alva-Valdivia Luis , Robles-Camacho Jasinto , del Sol Hernández-Bernal Ma. 
Published: August 2014

Abstract
As part of the effort to establish an archeointensity variation curve for Mesoamerica, 13 archeologically well-identified pottery samples belonging to the Ocozocoautla site (Chiapas) were studied. Analyzed samples consist of ‘ofrenda type’ pottery fragments found in several caves. Three archeological intervals are involved: 450-100 B.C., 200–550 A.D. and 550–900 A.D. The Thellier method in its modified form was applied to small fragments previously embedded in salt pellets. Raw intensity values were further corrected for cooling rate effects. The common time-consuming TRM anisotropy correction protocol was substituted by an alternative approach during the paleointensity experiments. Forty-two specimens, belonging to six samples, yielded high-quality Thellier determinations. The NRM fraction f used for paleointensity determination ranges between 0.42 to 0.99, and the quality factor q (Coe et al., 1978) varies from 4 to 59, being normally greater than 5. These results correspond to data of good quality. The mean archeointensity values per pottery fragments range from 14.6±1.5 to 59.5±13.8 μT, while the corresponding virtual axial dipole moments range from 2.5±0.3 to 10.0±2.4 × 1022 A m2. These new data, although not numerous, are of high quality and definitively contribute to the Mesoamerican, still insipient, archeointensity database.
Rock magnetism and microscopy of the Jacupiranga alkaline-carbonatitic complex, southern Brazil
Authors: Alva-Valdivia Luis M. , Perrin M. , Rivas-Sánchez María L. , Goguitchaichvili Avto , López-Loera Héctor , Lopes Omar Ferreira , Bonás Thiago Bastos 
Published: August 2014

Abstract
This study of the Cajati deposit provides evidence that the ore was neither purely hydrothermal, nor volcanic in origin, as previous workers have proposed. The ores were formed from magnetite-rich magmas, hydrothermally altered and intruded at an indicated crustal depth in excess of 500 m. The mineralogical and textural association between magnetite and magnesioferrite in the carbonatite, and between the titanomagnetite and magnesioferrite-Ti mineralization in the pyroxenite of hedenbergite, seems to be analog mineralizations strongly related to the ionic substitution of Fe2+ by Mg. Relatively high Q ratios (≥5) for Jacupirangite-pyroxenite may indicate a thermo remanent magnetization (TRM) by the ore during post-metamorphic cooling, however it can also be developed from chemical remanent magnetization (CRM). Vector plots for the pyroxenite samples show reasonably linear and stable magnetic components. The intensity decay curves show that only two components of magnetizations are likely present. Continuous susceptibility measurements with increasing temperature show that the main magnetic phase seems to be magnetite. Maghemite is probably produced during the cooling process. Susceptibility recorded from low temperature (liquid nitrogen (-196°C)) to room temperature produces typical curves, indicating Verwey transition of magnetite. Hysteresis parameters point out that nearly all values fall in a novel region of the Day plot, parallel to but below magnetite SD + MD mixing curves.
Ground effects of space weather investigated by the surface impedance
Authors: Pirjola Risto , Boteler David , Trichtchenko Larisa 
Published: August 2014

Abstract
The objective of this paper is to provide a discussion of the surface impedance applicable in connection with studies of geomagnetically induced currents (GIC) in technological systems. This viewpoint means that the surface impedance is regarded as a tool to determine the horizontal (geo)electric field at the Earth’s surface, which is the key quantity for GIC. Thus the approach is different from the traditional magnetotelluric viewpoint. The definition of the surface impedance usually involves wavenumber-frequency-domain fields, so inverse Fourier transforming the expression of the electric field in terms of the surface impedance and the geomagnetic field results in convolution integrals in the time and space domains. The frequency-dependent surface impedance has a high-pass filter character whereas the corresponding transfer function between the electric field and the time derivative of the magnetic field is of a low-pass filter type. The relative change of the latter transfer function with frequency is usually smaller than that of the surface impedance, which indicates that the geoelectric field is closer to the time derivative than to the magnetic field itself. An investigation of the surface impedance defined by the space-domain electric and magnetic components indicates that the largest electric fields are not always achieved by the plane wave assumption, which is sometimes regarded as an extreme case for GIC. It is also concluded in this paper that it is often possible to apply the plane wave relation locally between the surface electric and magnetic fields. The absolute value of the surface impedance decreases with an increasing wavenumber although the maximum may also be at a non-zero value of the wavenumber. The imaginary part of the surface impedance usually much exceeds the real part.
Source process for complex fault system of the 2007 Chuetsu-oki, Niigata, Japan, earthquake
Authors: Nakamura Takeshi , Ishihara Yasushi , Yamanaka Yoshiko , Kaneda Yoshiyuki 
Published: August 2014

AbstractThe 2007 Chuetsu-oki earthquake occurred in the offshore area of Niigata Prefecture, central Japan, on 16 July 2007. The aftershock distribution shows two fault planes, dipping to the northwest and southeast, respectively, which form a cross-sectional “V” pattern. We analyze the kinematic source process for the two fault planes consistent with the aftershock distribution using teleseismic body waveform data. Our results indicate that the mainshock initiated rupture on both faults northeast of their intersection and that the rupture propagated unilaterally southwestward along the southeast-dipping fault. The maximum slip is 1.6 m on the southeastdipping fault, and the seismic moments of northwest- and southeast-dipping faults are 8.0 × 1017N m (Mw5.9) and 7.5 × 1018N m (Mw6.5), respectively. The forward modeling of geodetic displacement from the obtained fault model is consistent with the GPS and InSAR measurements. Successive conjugate reverse faults around the source region are identified from the reflection seismic sections. We presume that stress changes and complicated structures in property and geometry around the source region are the dominant causal factors for generating the complexity of coseismic fault system.
Development of a distributed backup system and a recovery system for telemetric seismic data
Authors: Uehira Kenji 
Published: August 2014

Abstract
Fast, low-cost Internet lines have recently become available that rapidly transfer seismometer data. However, as in any fast transfer system, gaps frequently occur during data transmission. There are many causes for missing data packets at the receiving end, where is the data center side. I have developed a system that is meant to solve this problem. When the telemetry or the system is down at the data center end, data recovery is possible if the data are stored locally at each station. This means that the missing data can be re-sent after the required repairs have been made at the data center end. Therefore, I developed a concept of a distributed backup system that can store seismometer data for over 1 year locally at each station and developed a new protocol called “WIN Raw Data Recovery Protocol (WRRP)” for the efficient re-transmission of missing data.
Seismic structure of the subducting seamounts on the trench axis: Erimo Seamount and Daiichi-Kashima Seamount, northern and southern ends of the Japan Trench
Authors: Nishizawa Azusa , Kaneda Kentaro , Watanabe Naoko , Oikawa Mitsuhiro 
Published: August 2014

Abstract
We present detailed P-wave velocity models of subducting seamounts from two wide-angle seismic experiments across the Erimo Seamount and Daiichi-Kashima Seamount, northern and southern ends of the Japan Trench. Common characteristics of the velocity models of the seamounts are that the maximum crustal thicknesses of the seamounts are 12–17 km thicker than a typical oceanic crust and that Pn velocities beneath the seamounts are approximately 7.7 km/s, i.e., slower then those of the neighboring area. These features are very similar to the crustal models for the seamounts produced by the Cretaceous off-ridge volcanism on the Pacific Basin.
Numerical simulations of the solar corona and Coronal Mass Ejections
Authors: Poedts Stefaan , Jacobs Carla , van der Holst Bart , Chané Emmanuel , Keppens Rony 
Published: August 2014

Abstract
Numerical simulations of Coronal Mass Ejections (CMEs) can provide a deeper insight in the structure and propagation of these impressive solar events. In this work, we present our latest results of numerical simulations of the initial evolution of a fast CME. For this purpose, the equations of ideal MagnetoHydroDynamics (MHD) have been solved on a three-dimensional (3D) mesh by means of an explicit, finite volume solver, where the simulation domain ranges from the lower solar corona up to 30R
e. In order to simulate the propagation of a CME throughout the heliosphere, a magnetic flux rope is superposed on top of a stationary background solar (MHD) wind with extra density added to the flux rope. The flux rope is launched by giving it an extra initial velocity in order to get a fast CME forming a 3D shock wave. The magnetic field inside the initial flux rope is described in terms of Bessel functions and possesses a high amount of twist.
Characteristics of deformation structure around the 2007 Niigata-ken Chuetsu-oki earthquake detected by multi-channel seismic reflection imaging
Authors: No Tetsuo , Takahashi Narumi , Kodaira Shuichi , Obana Koichiro , Kaneda Yoshiyuki 
Published: August 2014

Abstract
A multi-channel seismic reflection (MCS) survey was conducted to investigate the tectonic structure off Niigata, which caused the 2007 Niigata-ken Chuetsu-oki earthquake, using the research vessel (R/V) KAIREI of the Japan Agency for Marine-Earth Science and Technology. Based on the results of data processing and interpretation of available data, three areas are identified according to seismic characteristics. The most deformed area is located on the continental shelf near the source region of the 2007 Niigata-ken Chuetsu-oki earthquake, i.e., the area east of the Yoneyama-Ogi Uplifts. A remarkable growth of folds, including fault-related folds, and a strong reflector dipping east is identifiable by localized strain concentrations. The second area is located between the Yoneyama-Ogi Uplifts and the Jouetsu Knoll in the Toyama Trough. Although the deformation of deposits in the second area was smaller than in the first area, folds are identified. The third area is located toward the west of the Jouetsu Knoll in the Toyama Trough. No significant deformed structures developed in this area. Based on the interpretation of stratigraphy obtained in previous studies, seismic characteristics, and well data, the development of an anticline was initiated by a compression field after about 3.6 Ma. In particular, the deformation of sedimentary layers by the compression field occurred rapidly after about 1.3 Ma. Folds have grown larger toward the east after about 1.3 Ma. In addition, subsidence of about 0.2 s in sedimentary layers can be seen at the western margin of the Yoneyama-Ogi Uplifts, suggesting that tectonic movement related to reverse faulting has advanced there very recently. From aftershock distribution on a depth section on line S-2 near the hypocentral region, most hypocenters were determined to be below the strong reflector. This result suggests that fold growth has accompanied past large earthquakes, such as the 2007 Niigata-ken Chuetsu-oki earthquake.
Local multi-polar expansions in potential field modeling
Authors: Minchev B. , Chambodut A. , Holschneider M. , Panet I. , Schöll E. , Mandea M. , Ramillien G. 
Published: August 2014

AbstractThe satellite era brings new challenges in the development and the implementation of potential field models. Major aspects are, therefore, the exploitation of existing space- and ground-based gravity and magnetic data for the long-term. Moreover, a continuous and near real-time global monitoring of the Earth system, allows for a consistent integration and assimilation of these data into complex models of the Earth’s gravity and magnetic fields, which have to consider the constantly increasing amount of available data. In this paper we propose how to speed up the computation of the normal equation in potential filed modeling by using local multi-polar approximations of the modeling functions. The basic idea is to take advantage of the rather smooth behavior of the internal fields at the satellite altitude and to replace the full available gravity or magnetic data by a collection of local moments. We also investigate what are the optimal values for the free parameters of our method. Results from numerical experiments with spherical harmonic models based on both scalar gravity potential and magnetic vector data are presented and discussed. The new developed method clearly shows that very large datasets can be used in potential field modeling in a fast and more economic manner.
A theory of rock core-based methods for in-situ stress measurement
Authors: Yamamoto Kiyohiko 
Published: August 2014

Abstract
The behavior of the inelastic strain of rocks under the loading of compression reflects the history of stresses applied to the rocks. A number of methods based on this rock property of stress memory have been proposed for measuring in-situ stress. The magnitudes of in-situ stress can be determined from drilled core samples by deformation rate analysis (DRA); in other words, rocks do have the property of in-situ stress memory. In general, the inelastic strain of rocks increases with an increase in applied stress difference. The Keiser effect observed in laboratory experiments is explained as the behavior of the inelastic strain of this well-known mode. However, this effect cannot be the mechanism of the in-situ stress memory because the effect does not potentially allow us to determine the magnitudes of previously applied stress. Here, I theoretically show that rocks exhibit another mode of inelastic strain under axial loading of compression—if locally concentrated stresses in rocks relax to some extent under in-situ stress at depth. The magnitudes of in-situ stress can be determined from the behavior of this mode of inelastic strain under axial loading. The results of DRA suggest that this hypothesis is actually valid and that it is not only valid for the DRA, but also for the other rock core-based methods used for measuring in-situ stress.
Calculation of the piezomagnetic field arising from uniform regional stress in inhomogeneously magnetized crust
Authors: Yamazaki Ken’ichi 
Published: August 2014

AbstractThis paper describes a simple procedure for the calculation of the piezomagnetic field arising from uniform regional stress in heterogeneously magnetized crust. There exists a strong similarity between the spatial distributions of anomalies in the geomagnetic total force values arising from magnetization structures in the Earth’s crust and those arising from piezomagnetic signals that arise from there. This similarity enables us to compute the piezomagnetic field due to uniform regional stress without the need to determine the explicit structure of magnetization intensities in the crust. This situation is similar to that of “reduction to the pole”, which is commonly used to interpret magnetic survey data. An explicit formula is presented that gives the 2-D spectrum of the piezomagnetic field from that of local magnetic anomalies; the formula is then applied to synthetic data. Calculated values are compared with the exact solution of the piezomagnetic field in order to assess the efficacy of the proposed method. The comparison verifies that calculations performed using the formula yield sufficiently accurate values for practical use.