bluuebunny/crossref_metadata_2025_split huggingface dataset:
Crucial effect of system compliance on the maximum stress estimation in the hydrofracturing method: Theoretical considerations and field-test verification
Authors: Ito Takatoshi , Igarashi Akira , Kato Harumi , Ito Hisao , Sano Osam 
Published: August 2014

Abstract
Why do the currently available data sets from field hydrofracturing tests indicate that the measured re-opening pressure lies close to the shut-in pressure far more often than can reasonably be expected? In order to explain such a strange phenomenon, it is necessary to take into consideration two additional factors, those of (1) a residual aperture of fracture and (2) hydraulic compliance of the test equipment, both of which are ignored in the conventional theory of hydraulic fracturing. The residual aperture causes pressure penetration into the fracture prior to opening, and its effect is to reduce the re-opening pressure by a factor of two from the value expected when the conventional theory is used. The conventional theory implies that the fracture always begins to open at a borehole pressure less than the shut-in pressure. However, due to the effect of large hydraulic compliance, the reopening pressure measured in the conventional manner becomes larger than the true reopening pressure and approaches the shut-in pressure. Contrary to this, the reopening pressure measured using the test equipment with sufficiently small compliance represents a good estimate of the true reopening pressure. This pressure is related to the maximum horizontal stress S
H, and its measured value allows us to estimate the value of S
H.
Conductivity, electric field and electron drift velocity within the equatorial electrojet
Authors: Rastogi R. G. , Chandra H. 
Published: August 2014

Abstract
Rocket-borne in-situ measurements of electron density and current density made from Thumba, India, on four occasions between 1966 and 1973 and on one flight from Peru in 1965 are studied along with the corresponding ground magnetometer data. The Cowling conductivity is computed using the yearly mean magnetic field values of 1965 and the atmospheric density values from the MSIS 1986 model. The rocket-borne measurements from Thumba cover different geophysical conditions of strong, moderate and partial counter-electrojet events. The vertical profiles of the measured current density and electron density are presented along with the computed Cowling conductivity, electron drift velocity and electric field. The peak current density occurred at 106–107 km over Thumba and at 109 km over Peru compared to 104 km over Brazil. Cowling conductivity peaks occurred at 102 km over Huancayo and 101 km over Thumba, while electron drift velocity and electric field peaks occurred at approximately 105–107 km over Thumba, 108 and 110 km over Huancayo and 104 km over Brazil, respectively. While the electron density near the level of peak current density shows some variability, electron drift velocity and electric field show large variability. We conclude that the local electric field plays an important role in the spatial and temporal variability of the strength of the electrojet.
Full particle simulation of a perpendicular collisionless shock: A shock-rest-frame model
Authors: Umeda Takayuki , Yamazaki Ryo 
Published: August 2014

Abstract
The full kinetic dynamics of a perpendicular collisionless shock is studied by means of a one-dimensional electromagnetic full particle simulation. The present simulation domain is taken in the shock rest frame in contrast to the previous full particle simulations of shocks. Preliminary results show that the downstream state falls into a unique cyclic reformation state for a given set of upstream parameters through the self-consistent kinetic processes.
Spatial variation of lithospheric heterogeneity on the globe as revealed from transverse amplitudes of short-period teleseismic P-waves
Authors: Kubanza Mungiya , Nishimura Takeshi , Sato Haruo 
Published: August 2014

Abstract
We systematically characterized the medium heterogeneity of the lithosphere by analyzing transverse-component amplitudes of teleseismic P-waves from shallow earthquakes in short periods of 0.5 to 4 Hz. Normalized transverse amplitudes, which are less affected by a layered structure, were measured at each station of the IRIS GSN network. The data revealed significant regional differences in lateral heterogeneity of the lithosphere, with small amplitudes observed at stations on stable continents and large normalized transverse amplitudes observed in seismically active regions, such as island arcs or collision zones. These spatial changes are consistent with the tectonic settings of each station. However, large normalized transverse amplitudes were also observed in regions of very low seismicity and in regions where no seismic activity has been recognized, which may indicate the existence of medium heterogeneity in the lithosphere that has been formed in ancient times.
Preliminary dielectric and rock magnetic results for a set of prehistoric Amerindian pottery samples from different Venezuelan Islands
Authors: Costanzo-Alvarez V. , Suárez N. , Aldana M. , Hernández M. C. , Campos C. 
Published: August 2014

Abstract
Potsherds from 7 Venezuelan islands have been studied using a two-fold magneto/dielectric technique in order to identify clay sources and characterize different stages of pottery craftsmanship. This is the first study of archeological material using this technique. Petrographic analyses appear to agree with the clusters of data identified in scatter plots of initial magnetic susceptibility versus saturation isothermal remanent magnetization (SIRM), and natural remanent magnetization (NRM). Thus, these magnetic parameters appear to be suitable for describing clay source characteristics. Effective magnetic grain sizes, investigated via stability analyses of SIRM and anystheretic remanent magnetization (ARM) upon alternating field (AF) demagnetization, and SIRM acquisition and AF demagnetization crossover plots, seem to be related to different steps of pottery craftsmanship, namely clay preparation, finishing and firing. Thermomagnetic curves might also provide valuable information about original firing conditions. A scatter plot of SIRMs intersections versus maximum current depolarization temperatures and average activation energies, shows a coarse correlation due perhaps to the fact that these rock magnetic and dielectric data are both associated to pore-related features.
Subsurface Chemistry of the Imbrium Basin Inferred from Clementine UVVIS Spectroscopy
Authors: Otake Hisashi , Mizutani Hitoshi 
Published: August 2014

Abstract
Since ejecta around an impact crater is excavated from a depth, its mineralogy and chemistry will provide us with information on the composition of the pre-impact subsurface. The depth from which crater ejecta were excavated was determined from laboratory experiments, field studies, and a simplified quantitative model (Z-model and the scaling law of ejection velocity). Based on the results of these studies, it is believed that surface material of an ejecta blanket between 1.1 and 1.5 radii from the crater was excavated from a depth of 0.13 to 0.15 radii. The following results were obtained from combining the surface and subsurface basalt distributions with crater-counting ages for the mare basalt, we obtained the following results: (1) The averages of TiO2 and FeO increased with time from the Imbrian to the Eratosthenian periods, which is represented by a continuous trend curve on the TiO2-FeO graph: (2) volcanic activities in Mare Imbrium drastically decreased and basalts changed from a low-Ti to high-Ti content around the transition of the Imbrian to Eratosthenian period: (3) basalts with less than 3 wt% TiO2 erupted in succession mainly in the Imbrian period.
A method for representing a geomagnetic total force field in a small region with special attention to discontinuities of data
Authors: Yamazaki Ken’ichi , Oshiman Naoto 
Published: August 2014

Abstract
In order to represent the total force field variation in a narrow region as precisely as possible, the calculation process of NOC, which is frequently used in geomagnetic field modeling, was improved. An iterative procedure was introduced to avoid the effect of data missing in some time series. The presented procedures are applied to monthly averaged data of the geomagnetic total force field during 1980–1997 in Japan. Some local changes are detected using this model. One of them may be related to an earthquake that took place near the site.
Undersea co-seismic crustal movements associated with the 2005 Off Miyagi Prefecture Earthquake detected by GPS/acoustic seafloor geodetic observation
Authors: Matsumoto Yoshihiro , Fujita Masayuki , Ishikawa Tadashi , Mochizuki Masashi , Yabuki Tetsuichiro , Asada Akira 
Published: August 2014

Abstract
We have been carrying out seafloor geodetic observations at two reference points situated off Miyagi Prefecture, northeastern Japan, using the GPS/Acoustic combination technique. Comparison of position estimates before and after the 2005 Off-Miyagi Prefecture Earthquake revealed a co-seismic crustal movement as large as 10 cm eastward at the site approximately 10 km from the epicenter, while no prominent movement was found at another site located 60 km away from the epicenter. The results at these two sites are consistent with crustal deformation calculated from the rectangular dislocation model on the fault derived from crustal movements observed at GEONET stations on land.
Trap thickness and the subtrappean structures related to mode of eruption in the Deccan Plateau of India: results from magnetotellurics
Authors: Patro B. P. K. , Sarma S. V. S. 
Published: August 2014

AbstractDeccan trap thickness is an important parameter in understanding the eruption process of flood basalts (65 My). A magnetotelluric study was carried out in Deccan Volcanic Province (DVP) of the Indian Peninsular shield during 1998–1999. Modeling results clearly revealed variations both in the thickness of the Deccan traps and in their resistivity from the west coast to the eastern boundary of DVP. The thickness of the traps in DVP decreases from about 1.8 km in the west to a few hundred meters (approx. 400 m) towards the east. The traps also exhibit considerable variation in resistivity, with higher resistivities (approx. 150–200 ohm-m) in the western half and lower resistivities (approx. 50–100 ohm-m) in the eastern half of DVP. Two significant fissure/fracture zones have been detected in DVP; these may have acted as conduits for the outpouring of Deccan lavas in addition to the primary structures along the west coast and the Narmada-Son lineament (NSL) zones.
Statistical study of medium-scale traveling ionospheric disturbances observed with the GPS networks in Southern California
Authors: Kotake Nobuki , Otsuka Yuichi , Ogawa Tadahiko , Tsugawa Takuya , Saito Akinori 
Published: August 2014

Abstract
Using global positioning system (GPS) data taken from 350 dual-frequency GPS receivers in Southern California in 2002, we investigated two-dimensional maps of total electron content (TEC) perturbations with a time resolution of 30 s and a spatial resolution of 0.15°×0.15° in longitude and latitude to reveal statistical characteristics of medium-scale traveling ionospheric disturbances (MSTIDs). We found that MSTIDs can be categorized into three types. One type is daytime MSTIDs, which frequently occur in winter and equinoxes. Since most of the daytime MSTIDs propagated southeastward, we speculate that the daytime MSTIDs could be caused by atmospheric gravity waves in the thermosphere. A second type is nighttime MSTIDs, which frequently occur in summer. Nighttime MSTIDs propagate southwestward. This propagation direction is consistent with the idea that polarization electric fields could play an important role in generating nighttime MSTIDs. The third is dusk MSTIDs, which frequently occur in summer and propagate northwestward. Dusk MSTIDs could be caused by gravity waves originating from the sunset terminator because they have wavefronts almost parallel to the sunset terminator.
In situ stress measurement by the stress relief technique using a multi-component borehole instrument
Authors: Mukai Atsushi , Yamauchi Tsuneo , Ishii Hiroshi , Matsumoto Sigeo 
Published: August 2014

Abstract
We have developed a two-dimensional method for calculating principal stresses on a plane by measuring strain changes obtained by the stress relief technique using a multi-component borehole instrument. If the ratio of the radius of the core to that of the borehole is 1.4–2.0, a uniform strain change occurs in any stress field due to the overcoring. It is therefore desirable that the radius of the core obtained by overcoring is larger than that of the borehole by a few orders of magnitude. We applied the proposed calculation method to a stress measurement performed at the Hishikari mine, southwest Japan. The maximum and minimum principal stresses were determined to be 5.0 and −0.2 MPa, respectively. The nearly vertical stress was estimated to be 1.5 MPa, which was merely 30% of the predicted vertical stress (5.6 MPa). One of causes of the small vertical stress obtained in this study is considered to be the limitation of the two-dimensional method for calculating principal stresses.
Analysis of pressure waves observed in Sakurajima eruption movies
Authors: Yokoo Akihiko , Ishihara Kazuhiro 
Published: August 2014

Abstract
Four eruption movies of Sakurajima volcano taken in the 1980s are analyzed. Pressure waves associated with these eruptions are identified by changes in luminance using a new image processing method. Results of the processing determined the apparent speeds of these waves at approximately 342–574 m/s. Further, spatial characteristics of the pressure waves are quantitatively investigated to estimate the source conditions of volcanic explosions.
Milestones of the IAGA International Service of Rapid Magnetic Variations and its contribution to geomagnetic field knowledge
Authors: Curto J. J. , Cardús J. O. , Alberca L. F. , Blanch E. 
Published: August 2014

Abstract
The Service of Rapid Magnetic Variations (RMV) was created by the International Association of Geomagnetism and Aeronomy (IAGA) with the aim of obtaining an overall view of the temporal and spatial distribution of RMV as a base for further study of these phenomena. The Ebro Observatory participated in the creation of this service and has been administering it from the beginning; consequently, the histories of these two organizations are intertwined.
Evidence for an elevated 410 km discontinuity below the Luzon, Philippines region and transition zone properties using seismic stations in Taiwan and earthquake sources to the south
Authors: Wright C. , Kuo B.-Y. 
Published: August 2014

Abstract

P waves from earthquakes south of Taiwan, recorded by seismic stations within and around Taiwan, were used to define two average wavespeed models WPSP01 and WPSP02 for the upper mantle and transition zone below the Luzon region. Wavespeeds are characteristic of oceanic upper mantle. The 410-km discontinuity, however, appears to be elevated to about 325 km depth, based on clear identification of the travel-time branch produced by refraction within the transition zone, and estimates of its first and second derivatives with respect to distance. A plausible explanation is low temperatures within the subducted South China Sea plate. The data also imply relatively low wavespeed jumps of 0.6–1.0% and 1.1–1.5% respectively across the elevated 410-km discontinuity and a lower discontinuity at 676 km depth, and high wavespeed gradients in the transition zone. Phase-weighted stacking on a cluster of short-period seismograms with first arrival energy from within the transition zone provides independent support for the validity of the models; later arrivals are detected close to the predicted times and slownesses for energy emerging from the lowermost upper mantle and the top of the lower mantle. An additional arrival on the stacks may be caused by a localized discontinuity near 530 km depth.
Automatic seismic wave arrival detection and picking with stationary analysis: Application of the KM2O-Langevin equations
Authors: Nakamula Sho , Takeo Minoru , Okabe Yasunori , Matsuura Masaya 
Published: August 2014

AbstractAn automatic detection and a precise picking of the arrival times of seismic waves using digital seismograms are important for earthquake early detection systems. Here we suggest a new method for detecting and pickingP-andS-wave signals automatically. Compared to methods currently in use, our method requires fewer assumption with properties of the data time series. We divide a record into intervals of equal lengths and check the “local and weak stationarity” of each interval using the theory of the KM2O-Langevin equations. The intervals are stationary when these include only background noise, but the stationarity breaks abruptly when a seismic signal arrives and the intervals include both the background noise and theP-wave. This break of stationarity makes us possible to detectP-wave arrival. We expand the method for picking ofS-waves. We applied our method to earthquake data from Hi-net Japan, and 90% ofP-wave auto-picks were found to be within 0.1 s of the corresponding manual picks, and 70% ofS-wave picks were within 0.1 s of the manual picks. This means that our method is accurate enough to use as a part of the seismic early detection system.
Thermal and hydrostatic structure of the protoplanetary nebula exposed to stellar radiation and stellar wind from the central star
Authors: Yun Young Seok , Emori Hiroyuki , Nakazawa Kiyoshi 
Published: August 2014

Abstract
A model for a nebula exposed to the radiation and stellar wind from the central star has been examined. T Tauri stars commonly have disks and stellar wind, though we have no theoretical model on nebular thermal structure under the wind. The aims of this paper are to propose a theoretical nebula model, and to perform mathematical analysis on the geometrical structure and temperature distribution of a passive nebula. Its geometrical surface is determined by the dynamical pressure of the stellar wind. The nebular surface is assumed to be a black body surface, heated by the incident stellar photon flux. We obtain temperature from the equation of energy balance between the stellar radiation upon this nebular surface and the black body radiation from it. The temperature distribution in passive disks is insensitive to the wind strength and is almost identical even if the wind strength changes by five orders of magnitude. The nebula temperature is not expressed by a simple power law function of the distance from the central star. This is an important difference between our results and those of previous works. Since the nebula surrounding a T Tauri star is influenced by stellar wind, our model may be more appropriate than any other simple single power law temperature for passive protoplanetary nebulae.
Gravitational energy release in an evolving Earth model
Authors: Roberts Paul H. , Kono Masaru 
Published: August 2014

Abstract
The energy budget of the Earth’s core balances the heat lost through cooling with the sum of gravitational, latent heat and radioactive sources (if any). The gravitational and latent heat sources are due to the freezing of core mix onto the surface of the inner core. Gravitational energy is released because the light components of core mix that are released during freezing are buoyant, and rise as they rejoin the fluid core. This source of energy can be regarded as part of the total gravitational energy released as the entire Earth cools and contracts. The main purpose of this paper is to present a new method of evaluating the total energy release. The method is applied to two Earth models. Both show that the gravitational source that stirs the fluid core is less than 30% of the total gravitational energy released through the contraction of the Earth as it cools.
A new type of a three-component spinner magnetometer to measure the remanence of rocks at elevated temperature
Authors: Wack Michael , Matzka Jürgen 
Published: August 2014

Abstract
A new instrument to continuously determine the remanent magnetisation of standard paleomagnetic (inchsized) rock samples during heating and cooling (continuous thermal demagnetisation) was developed. The design as an off-axis spinner magnetometer (i.e. the samples rotate on a circular path in a radial distance to the spinning axis) allows the simultaneous measurement of several samples and offers a way to determine the full vector of magnetisation. Six fluxgate sensors are used to record three gradients of the magnetic fields caused by the samples and the vector of remanence is determined by regression analysis of the gradient signals. The sensitivity of the instrument is 2·10−7 Am2. Hot air is circulating through copper pipes which heat the samples by thermal radiation to avoid magnetic fields which would arise from direct electrical heating. Currently, the measurements are restricted to a maximum of 350°C. The instrument was tested with oceanic basalt samples that were given an artificial remanence. Some continuous thermal demagnetisation experiments of this artificial remanence and of the natural remanent magnetisations are shown for oceanic basalts.
The 2004 Las Campanas/Lowell Observatory campaign II. Surface properties of Hayabusa target Asteroid 25143 Itokawa inferred from Hapke modeling
Authors: Lederer S. M. , Domingue D. L. , Thomas-Osip J. E. , Vilas F. , Osip D. J. , Leeds S. L. , Jarvis K. S. 
Published: August 2014

Abstract
We present an analysis of Hapke photometric modeling applied to uniform ground-based UBVRIJHK broadband data of asteroid 25143 Itokawa collected over a wide range of solar phase angles (4°–130°) during the 2004 apparition (Thomas-Osip et al., this issue, hereafter Paper I). Our photometric analyses indicate that Itokawa has a blocky surface with properties different from other, albeit larger, S-class asteroids studied using similar Hapke modeling analyses. Images from the Hayabusa spacecraft affirm the Hapke modeling results, demonstrating the ability of Hapke photometric modeling to predict a rocky asteroid surface correctly; this is the first time that a predicted rocky surface has been observed by a spacecraft. The single particle scattering functions are dominantly forward scattering, suggesting the surface material is composed primarily of clear particles whose scattering is dictated by the particle’s surface as opposed to internal scatterers (more typical of S-class asteroids), while the opposition parameters indicate that the regolith may be more compact than most of the limited number of asteroids visited by spacecraft to date. The roughness properties, single particle scattering properties, and opposition surge characteristics are all indicative of a surface where multiple scattering does not play a major role in defining the photometric properties of the regolith.
Fault model of the 2007 Noto Hanto earthquake estimated from PALSAR radar interferometry and GPS data
Authors: Fukushima Yo , Ozawa Taku , Hashimoto Manabu 
Published: August 2014

Abstract
The 2007 Noto Hanto earthquake (M
w 6.6) is the first major earthquake in inland Japan since the launch of the Japanese ALOS satellite. Interferometric synthetic aperture radar successfully mapped the coseismic displacements from both ascending and descending orbits in and around the earthquake epicentral region. The line-of-sight displacements toward the satellite from the ascending and descending orbits amount to about 50 and 20 cm, respectively. The interferograms as well as the GPS data of the GEONET network are inverted in order to determine the slip distribution on the source fault. The dip and strike angles of the preferred model are 48° and N51°E, respectively, and its fault slip area reaches the seafloor. The dip angle is not well constrained in our tested range between 40° and 60°. The dominant slip area is located just above the hypocenter, at depths between 4 and 10 km. Many aftershocks seem to have occurred on and around the area of dominant slip.