bluuebunny/crossref_metadata_2025_split huggingface dataset:
Three-dimensional velocity structure in the source region of the Noto Hanto Earthquake in 2007 imaged by a dense seismic observation
Authors: Kato Aitaro , Sakai Shinichi , Iidaka Takashi , Iwasaki Takaya , Kurashimo Eiji , Igarashi Toshihiro , Hirata Naoshi , Kanazawa Toshihiko ,   Group for the aftershock observations of the 2007 Noto Hanto Earthquake
Published: August 2014

Abstract
The velocity structure and accurate aftershock distributions of the Noto Hanto Earthquake in 2007 (thrust type) are elucidated by inverting the arrival times from 917 aftershocks using double-difference tomography. P-wave velocity (V

p
) of the hanging wall in the southeast appears to be higher than that of the footwall in the northwest, and the high-V

p
body of the hanging wall has a relatively high V

p
/V

s
ratio. Conversely, the low-V

p
body in the footwall appears to have a low V

p
/V

s
ratio at depths greater than 3 km. Aftershocks associated with the mainshock fault are roughly distributed along this velocity boundary between the hanging wall and footwall. Near-surface thin layers with significantly low V

p
and high V

p
/V

s
are imaged in a northwest direction from the mainshock epicenter. A likely explanation is that the mainshock fault plane was reactivated as a reverse fault in terms of the inversion tectonics due to the crustal shortening which initiated from the late Miocene. Both the mainshock hypocenter and the vertical alignment of aftershocks beneath it are located in the low-V

p
and low-V

p
/V

s
zones, indicating the potential presence of water-filled pores. Crustal stretching and shortening in and around the Noto Peninsula have created complex structures, including weak high-dip angle faults, almost vertical faults, and low velocity zones, which can potentially affect the seismic activities around the source region.
Auroral radio emission and absorption of medium frequency radio waves observed in Iceland
Authors: Sato Yuka , Ono Takayuki , Iizima Masahide , Kumamoto Atsushi , Sato Natsuo , Kadokura Akira , Miyaoka Hiroshi 
Published: August 2014

Abstract
In order to study the generation and propagation processes of MF auroral radio emissions (referred to as auroral roar and MF burst) in the polar ionosphere, an Auroral Radio Spectrograph (ARS) system was installed at Husafell station in Iceland (invariant latitude: 65.3°). Data analysis of man-made transmissions also provides useful information for the ionosphere study as well as an investigation of auroral radio emissions since the propagation character of MF radio waves changes depending on electron-neutral collisions in the bottomside ionosphere. Thus, ionospheric absorption is examined in comparison with the solar zenith angle and auroral phenomena. The results indicate that the ARS data can be used to detect ionization occurring at distant regions. In late 2006, the ARS detected one auroral roar and twoMF bursts, which were identified as left-handed polarized waves. Results of data analysis, including other auroral data and particle spectra observed by the DMSP satellite, suggest that the MF bursts are generated by electrons with an average energy of several keV associated with auroral breakup. On the other hand, the auroral roar is generated as upper hybrid waves by relatively low-energy electrons over the observation site and propagates downward, being converted into L-O mode electromagnetic waves.
Ionospheric hole behind an ascending rocket observed with a dense GPS array
Authors: Furuya Tomoaki , Heki Kosuke 
Published: August 2014

Abstract
An ascending liquid-fuel rocket is known to make a hole in the ionosphere, or localized electron depletion, by leaving behind large amounts of neutral molecules (e.g. water) in the exhaust plume. Such a hole was made by the January 24, 2006 launch of an H-IIA rocket from Tanegashima, Southwestern Japan, and here we report its observation with a dense array of Global Positioning System receivers as a sudden and temporary decrease of total electron content. The observed disturbances have been compared with a simple numerical model incorporating the water diffusion and chemical reactions in the ionosphere. The substantial vanishing of the ionosphere lasted more than one hour, suggesting its application as a window for ground-based radio astronomical observations at low frequencies.
An improved scheme for modeling the reflectance spectra of space-weathered regoliths
Authors: Nimura Tokuhiro , Hiroi Takahiro , Pieters Carle M. 
Published: August 2014

Abstract
In the remote detection of mineral compositions of planetary surface materials on airless bodies, space weathering is an obstacle which makes reflectance spectra redder and darker and weakens spectral features. This study attempts to model an effect of space weathering due to vapor coating by accounting for the change in surface reflectivity of regolith particles wherein nanophase-reduced iron (npFe0) particles are concentrated on their surfaces. When applied to a suite of reflectance spectra of lunar soils having different degrees of space weathering, this model can estimate the degrees of space weathering in terms of the thicknesses of the coating layer and provide an absorption coefficient spectrum of the host material.
Gamma-ray spectrometer (GRS) for lunar polar orbiter SELENE
Authors: Hasebe Nobuyuki , Shibamura Eido , Miyachi Takashi , Takashima Takeshi , Kobayashi Masanori , Okudaira Osamu , Yamashita Naoyuki , Kobayashi Shingo , Ishizaki Takeshi , Sakurai Kunitomo , Miyajima Mitsuhiro , Fujii Masayuki , Narasaki Keisuke , Takai Shigeki , Tsurumi Katsuhiro , Kaneko Hiroshi , Nakazawa Michio , Mori Kunishiro , Gasnault Olivier , Maurice Sylvestre , d’Uston Claude , Reedy Robert C. , Grande Manuel 
Published: August 2014

Abstract
The high-precision gamma-ray spectrometer (GRS) on the lunar polar orbiter SELENE is designed to measure 200 keV—12 MeV gamma rays in order to determine elemental compositions of the lunar surface. The GRS consists of a large germanium (Ge) crystal as a main detector and a massive bismuth germanate crystal and a plastic scintillator as anticoincidence detectors. The Ge detector is cooled by a Stirling cryocooler with its compressor attached to a passive radiator facing the cold space. The cooling system maintains the Ge detector below 90 K during the observation. The flight model of the GRS has achieved an energy resolution of 3.0 keV (FWHM) at 1333 keV. Energy spectra obtained by the GRS will show sharp gamma-ray lines whose energies identify the elements and whose intensities determine the concentrations of the elements, permitting global mapping of the elemental abundances in the sub-surface of the Moon. The elemental maps obtained by the GRS with such high-energy resolution enable us to study lunar geoscience problems.
Electromagnetic compatibility (EMC) evaluation of the SELENE spacecraft for the lunar radar sounder (LRS) observations
Authors: Kumamoto A. , Ono T. , Kasahara Y. , Goto Y. , Iijima Y. , Nakazawa S. 
Published: August 2014

Abstract
In order to achieve the lunar subsurface sounding and planetary radio wave observations by the Lunar Radar Sounder (LRS) onboard the SELENE spacecraft, strict electromagnetic compatibility (EMC) requirements were applied for all instruments and the whole system of the spacecraft. In order to detect the lunar subsurface echoes from a depth of 5 km, the radiated emission (RE) limit was determined to be −10 dBμV/m and the common-mode (CM) current limit to be 20 dBμA. The EMC performance of the spacecraft was finally evaluated in the system EMC test held from Oct. 20 to Oct. 22, 2005. There is no broadband noise but some narrowband noises at a level above the CM-current limit in a frequency range from 4 to 6 MHz, in which radar soundings are operated. Based on the noise spectrum within 4–6 MHz, the noise level of FMCW radar sounder is estimated to be 14 dB lower than the CM-current limit. In the SELENE EMC test, the following new techniques were introduced: (1) systematic control and evaluation of CM-current noises were first performed to improve the spacecraft EMC performance; (2) onboard battery operation was utilized for reduction of ambient broadband noises during EMC measurements.
Low-energy charged particle measurement by MAP-PACE onboard SELENE
Authors: Saito Yoshifumi , Yokota Shoichiro , Asamura Kazushi , Tanaka Takaaki , Akiba Ryota , Fujimoto Masaki , Hasegawa Hiroshi , Hayakawa Hajime , Hirahara Masafumi , Hoshino Masahiro , Machida Shinobu , Mukai Toshifumi , Nagai Tsugunobu , Nagatsuma Tsutomu , Nakamura Masato , Oyama Koh-ichiro , Sagawa Eiichi , Sasaki Susumu , Seki Kanako , Terasawa Toshio 
Published: August 2014

Abstract
MAP-PACE (MAgnetic field and Plasma experiment-Plasma energy Angle and Composition Experiment) is one of the scientific instruments onboard the SELENE (SELenological and ENgineering Explorer) satellite. PACE consists of four sensors: ESA (Electron Spectrum Analyzer)-S1, ESA-S2, IMA (Ion Mass Analyzer), and IEA (Ion Energy Analyzer). ESA-S1 and S2 measure the distribution function of low-energy electrons below 15 keV, while IMA and IEA measure the distribution function of low energy ions below 28 keV/q. Each sensor has a hemispherical field of view. Since SELENE is a three-axis stabilized spacecraft, a pair of electron sensors (ESA-S1 and S2) and a pair of ion sensors (IMA and IEA) are necessary for obtaining a three-dimensional distribution function of electrons and ions. The scientific objectives of PACE are (1) to measure the ions sputtered from the lunar surface and the lunar atmosphere, (2) to measure the magnetic anomaly on the lunar surface using two ESAs and a magnetometer onboard SELENE simultaneously as an electron reflectometer, (3) to resolve the Moon-solar wind interaction, (4) to resolve the Moon-Earth’s magnetosphere interaction, and (5) to observe the Earth’s magnetotail.
Ray-traced troposphere slant delays for precise point positioning
Authors: Hobiger Thomas , Ichikawa Ryuichi , Takasu Tomoji , Koyama Yasuhiro , Kondo Tetsuro 
Published: August 2014

Abstract
Precise satellite orbits and clock information for global navigation satellite systems (GNSS) allow zero-difference position solutions, also known as precise point positioning (PPP) to be calculated. In recent years numerical weather models (NWM) have undergone an improvement of spatial and temporal resolution. This makes them not only useful for the computation of mapping functions but also allows slant troposphere delays from ray-tracing to be obtained. For this study, such ray-traced troposphere corrections have been applied to code and phase observations of 13 sites from the International GNSS Service (IGS) receiver network, which are located inside the boundaries of the Japanese Meteorological Agency (JMA) meso-scale weather model, covering a period of 4 months. The results from this approach are presented together with a comparison to standard PPP processing results. Moreover the advantages and caveats of the introduction of ray-traced slant delays for precise point positioning are discussed.
Deformation of the Augustine Volcano, Alaska, 1992–2005, measured by ERS and ENVISAT SAR interferometry
Authors: Lee Chang-Wook , Lu Zhong , Kwoun Oh-Ig , Won Joong-Sun 
Published: August 2014

Abstract
The Augustine Volcano is a conical-shaped, active stratovolcano located on an island of the same name in Cook Inlet, about 290 km southwest of Anchorage, Alaska. Augustine has experienced seven significant explosive eruptions—in 1812, 1883, 1908, 1935, 1963, 1976, 1986, and in January 2006. To measure the ground surface deformation of the Augustine Volcano before the 2006 eruption, we applied satellite radar interferometry using Synthetic Aperture Radar (SAR) images from three descending and three ascending satellite tracks acquired by European Remote Sensing Satellite (ERS) 1 and 2 and the Environment Satellite (ENVISAT). Multiple interferograms were stacked to reduce artifacts caused by atmospheric conditions, and we used a singular value decomposition method to retrieve the temporal deformation history from several points on the island. Interferograms during 1992 and 2005 show a subsidence of about 1–3 cm/year, caused by the contraction of pyroclastic flow deposits from the 1986 eruption. Subsidence has decreased exponentially with time. Multiple interferograms between 1992 and 2005 show no significant inflation around the volcano before the 2006 eruption. The lack of a pre-eruption deformation signal suggests that the deformation signal from 1992 to August 2005 must have been very small and may have been obscured by atmospheric delay artifacts.
Geohazard assessment from satellite magnetic data modeling—with examples from the Arctic Margin along the Canada Basin and the Korean Peninsula along 40°N (latitude) parallel
Authors: Taylor Patrick T. , Kim Hyung Rae , Kutina Jan , Johnson G. Leonard 
Published: August 2014

AbstractLong-wavelength, relative high-amplitude-magnetic anomalies obtained at satellite altitudes have provided an understanding of the nature of the deeper crust of the Earth. We have studied two such long-wavelength anomalies in regions of high stress—one with a large and one with a lower amplitude anomaly. The first feature is on the Canada Basin continental margin in the Northwest and Yukon Territories, Canada (magnetic anomaly range: 19 nT to −6 nT at 350-km altitude). This area is also the focus of significant stress and earthquake activity. We interpret this anomaly and associated tectonic activity with this region’s position at or near the fulcrum of the scissors-like opening of the Canada Basin in the mid-Mesozoic Era. The second is a section along the 40°N (latitude) parallel crossing the Korean Peninsula (magnetic anomaly range: <−2 nT to >3 nT at 350-km altitude), where an east-west fracture zone has been proposed to extend from northeastern China, across the Korean Peninsula, Sea of Japan and (Northern) Japan.
Subsurface structure of the Myojin Knoll pumiceous volcano obtained from multichannel seismic reflection data
Authors: Tsuru Tetsuro , Okuda Ayumi , No Tetsuo , Kaneda Yoshiyuki , Tamaki Kensaku 
Published: August 2014

Abstract
The Myojin Knoll is a submarine volcano that has a classically beautiful conical-shaped silicic caldera whose surface is covered by pumice. To determine the tectonic structure inside the caldera wall and beneath the caldera floor of this pumicious submarine volcano, we carried out a structural interpretation study using newly collected deep-penetrating multichannel seismic (MCS) reflection data. We also conducted a detailed velocity analysis of the MCS data, which facilitated the interpretation study. The results demonstrate that approximately 90% of the caldera wall is composed of pumiceous volcanic breccia. This finding supports those of previous researchers who, based on seafloor observations, single-channel seismic reflection, and gravity and geomagnetic data, concluded the Myojin Knoll is a knoll having a pumiceous caldera wall underlain by a pre-caldera rhyolitic stratovolcano edifice. We also determined a down-warping reflector approximately 800 m beneath the caldera floor. A seismic unit immediately above the reflector has a higher P-wave velocity than the pumice units and shows a chaotic seismic reflection pattern. We interpreted the reflector to be the bottom of a possible shallow magma chamber where the magma would undergo repeated expansion and contraction as a result of recurrent eruption activities.
A conservative and non-oscillatory scheme for Vlasov code simulations
Authors: Umeda Takayuki 
Published: August 2014

Abstract
A new numerical positive interpolation technique for conservation laws and its application to Vlasov code simulations are presented. In recent Vlasov simulation codes, the Vlasov equation is solved based on the numerical interpolation method because of its simplicity of algorithm and its ease of programming. However, a large number of grid points are needed in both configuration and velocity spaces to suppress numerical diffusion. In this paper we propose a new high-order interpolation scheme for Vlasov simulations. The current scheme is non-oscillatory and conservative and is well-designed for Vlasov simulations. This is compared with the latest interpolation schemes by performing one-dimensional electrostatic Vlasov simulations.
An improved regularization method for estimating near real-time systematic errors suitable for medium-long GPS baseline solutions
Authors: Luo Xiaowen , Ou Jikun , Yuan Yunbin , Gao Jinyao , Jin Xianglong , Zhang Kefei , Xu Huajun 
Published: August 2014

Abstract
It is well known that the key problem associated with network-based real-time kinematic (RTK) positioning is the estimation of systematic errors of GPS observations, such as residual ionospheric delays, tropospheric delays, and orbit errors, particularly for medium-long baselines. Existing methods dealing with these systematic errors are either not applicable for making estimations in real-time or require additional observations in the computation. In both cases, the result is a difficulty in performing rapid positioning. We have developed a new strategy for estimating the systematic errors for near real-time applications. In this approach, only two epochs of observations are used each time to estimate the parameters. In order to overcome severe ill-conditioned problems of the normal equation, the Tikhonov regularization method is used. We suggest that the regularized matrix be constructed by combining the a priori information of the known coordinates of the reference stations, followed by the determination of the corresponding regularized parameter. A series of systematic errors estimation can be obtained using a session of GPS observations, and the new process can assist in resolving the integer ambiguities of medium-long baselines and in constructing the virtual observations for the virtual reference station. A number of tests using three medium- to long-range baselines (from tens of kilometers to longer than 1000 kilometers) are used to validate the new approach. Test results indicate that the coordinates of three baseline lengths derived are in the order of several centimeters after the systematical errors are successfully removed. Our results demonstrate that the proposed method can effectively estimate systematic errors in the near real-time for medium-long GPS baseline solutions.
Ultra-rapid UT1 measurement by e-VLBI
Authors: Sekido Mamoru , Takiguchi Hiroshi , Koyama Yasuhiro , Kondo Tetsuro , Haas Rüdiger , Wagner Jan , Ritakari Jouko , Kurihara Shinobu , Kokado Kensuke 
Published: August 2014

Abstract
The latency of UT1 measurement with Very Long Baseline Interferometry (VLBI) has been greatly reduced by using e-VLBI technology. VLBI observations on the baseline formed by the Kashima 34-m and the Onsala 20-m radio telescopes achieved ultra-rapid UT1 measurements, where the UT1 result was obtained within 30 min after the end of the observing session. A high speed network and a UDP-based data transfer protocol ‘Tsunami’ assisted the high data rate and long-distance data transfer from Onsala to Kashima. The accuracy of the UT1 value obtained from the 1-h single baseline e-VLBI experiment has been confirmed to be as the same level with the rapid combined solution of Bulletin-A. The newly developed technology is going to be transferred to the regular intensive VLBI sessions, and it is expected to contribute to the improved latency and accuracy of UT1 data.
First GPS-TEC evidence for the wave structure excited by the solar terminator
Authors: Afraimovich E. L. 
Published: August 2014

Abstract
Using TEC measurements from the global network of GPS receivers, we have obtained the first evidence for the wave structure excited by the solar terminator (ST), moving over the USA, Europe, and Japan. Two main types of the observed TEC disturbance were found: large-scale (LS) 60-min variations with an amplitude of about 0.5–1 TECU and medium-scale (MS) 15-min variations with an amplitude of about 0.05–0.1 TECU. The first type of disturbances was predicted in theoretical investigations and registered earlier using different methods of ionosphere radio sounding. The second type of the observed TEC disturbance is wave packets (WPs) generated when the time derivative of TEC is at its maximum. These WPs have duration of about 1–2 h and a time shift of about 1.5–2.5 h after the ST appearance at an altitude of 100 km. That ST-generated wave packets have been found for the first time. LS TEC disturbances and MS WPs are space-fixed along the ST line over a distance exceeding 1600 km.
Magnetic poles and dipole tilt variation over the past decades to millennia
Authors: Korte M. , Mandea M. 
Published: August 2014

Abstract
Due to the strong dipolar character of the geomagnetic field the shielding effect against cosmic and solar ray particles is weakest in the polar regions. We here present a comprehensive study of the evolution of magnetic and geomagnetic pole locations and the Earth’s magnetic core field in both polar regions over the past few years to millennia. North and south magnetic poles change independently according to the asymmetric complexity of the field in the two hemispheres, and the changes are not correlated to variations of the dipole axis. The recent, strong acceleration of the north magnetic pole motion appears to be linked to a reverse flux patch at the coremantle boundary, and an increasing deceleration of the pole over the next years seems likely. Over the whole studied period of 7000 years two periods of comparatively high velocity of the north magnetic pole are observed at 4500 BC and 1300 BC, based on the presently available data and models. Geographic latitudes and longitudes of magnetic and geomagnetic poles based on the studied geomagnetic field models are available together with animations of the poles and polar field behaviour from our webpage http://www.gfz-potsdam.de/geomagneticfield/poles.
TEC anomalies—Local TEC changes prior to earthquakes or TEC response to solar and geomagnetic activity changes?
Authors: Afraimovich Edward L. , Astafyeva Elvira I. 
Published: August 2014

Abstract
A number of papers have reported on deviations of daily values of the maximum electron concentration of the ionospheric F
2 layer and/or total electron content (TEC) in the vicinity of an earthquake’s epicenter some time prior to the quake. Owing to the importance of this problem, a question of a “locality” of those effects is emerging. To study this issue we have developed a method based on the calculation of global electron content and of local electron content in “check-region” with low seismic activity. The effect of TEC day-to-day changes before strong earthquakes is analyzed in this work. It is shown that in some cases this effect might be a reflection of global changes of the ionization caused by the 27-day variations as well as other fast alterations due to solar and geomagnetic activity changes. We discuss the problem of certain data corrections that permit local changes to be distinguished from global ones.