bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characteristics of the equatorial electrojet current in the central region of South America
Authors: Rastogi R. G. , Chandra H. , James M. E. , Kitamura K. , Yumoto K. 
Published: August 2014

Abstract
We describe here for the first time the morphology of the equatorial electrojet (EEJ) in the Central American Sector based on an analysis of the geomagnetic field components from six stations distributed on both sides of the dip equator along the 60°W geographic longitude sector. Diurnal and latitudinal variations in the horizontal and vertical components are shown to follow the Chapman model of EEJ. The horizontal component vector due to the ionospheric current aligned itself close to magnetic north, with a mean Declination of 10°W (ranging from 9°W to 14°W). There was a significant counter-electrojet effect before sunrise at stations close to the dip equator, suggesting late reversal of solar-quiet (S
q) electric field in the morning hours. The observed variations in the magnetic meridional current did not seem to be associated with EEJ currents. The centre of the electrojet was around 0.25°S of the dip equator in the morning hours and shifted gradually to 1.5°S by the evening hours. Magnetic storms occurring during the midday hours produced an exceptionally large decrease in the H (horizontal component) field at stations close to the dip equator.
Premonitory changes in seismicity prior to the Great Sumatra-Andaman earthquake of December 26, 2004
Authors: Imoto M. , Yamamoto N. 
Published: August 2014

Abstract
We studied changes in seismicity in a source region of the Sumatra earthquake prior to the earthquake on 26 December 2004. Rate increases were detected for earthquakes of M ≥ 5.0 using the ETAS method, with the assumption that independent events follow the Poisson process with at most only one rate change. Based on the declustered catalogue, we obtained consistent changes with simple Poisson models. Temporal changes in mean magnitude were obtained using the CUSUM method. b-values for three periods were calculated, taking into consideration the results of the CUSUM analysis, which showed a 10-year period of an anomaly high b-value followed by a 13-year period of a low b-value. The statistical significance of this change was confirmed by a bootstrap method. Both changes imply activation of seismicity in the source region.
Crustal deformation and a preliminary fault model of the 2007 Chuetsu-oki earthquake observed by GPS, InSAR, and leveling
Authors: Nishimura Takuya , Tobita Mikio , Yarai Hiroshi , Ozawa Shinzaburo , Murakami Makoto , Yutsudo Toru , Ishimoto Masayoshi , Umesawa Takeshi , Toyofuku Takashi , Kawamoto Satoshi , Amagai Tomomi , Fujiwara Midori , Suzuki Akira , Enya Syunji , Sasaki Toshiyuki , Yokokawa Masanori , Oomori Syuichi , Tanoue Setsuo , Ikeda Hisao , Nemoto Moriyuki , Suito Hisashi , Hayashi Fumi , Une Hiroshi , Koarai Mamoru , Tsuzawa Masaharu 
Published: August 2014

AbstractThe 2007 Chuetsu-oki earthquake occurred just west off the coast of Kashiwazaki in Niigata Prefecture, Central Japan on July 16, 2007. The permanent GPS network (GEONET) clarifies the coseismic displacement as a thrust faulting whose compressional axis lies in the NW-SE direction. Interferometric analysis of synthetic aperture radar (SAR) images acquired by “Daichi” satellite (ALOS) maps a detailed spatial pattern of the displacement toward the satellite for both ascending and descending orbits. Peak-to-peak displacement reaches approximately 400 mm in the descending orbit interferometric (In)SAR data. Repeated precise leveling shows uplift near the northeast part of the aftershock area and subsidence near the southwestern part. We construct a preliminary fault model by inverting the observed deformation. The preferred model consists of two segments of rectangular faults whose moment magnitude is 6.7 in total. From only the used geodetic data on land, it is difficult to determine which plane in two conjugate planes of the focal solution was ruptured. It is important to consider the effect of a heterogeneous medium and variable slip on the faults as well as other geophysical data to determine the fault model with confidence.
Broadband P waves transmitting through fracturing Westerly granite before and after the peak stress under a triaxial compressive condition
Authors: Yoshimitsu Nana , Kawakata Hironori , Takahashi Naoki 
Published: August 2014

Abstract
We analyzed temporal changes in the velocity and amplitude of P waves transmitted through a granite sample during a triaxial compression test, with the goal of monitoring the fault formation process associated with open and shear cracking. We used newly developed transducer assemblies for the broadband recording, and we continued to record transmitting waves even after the peak stress occurred. For transmitting P waves with paths parallel to the maximum compressive axis, we found that both the first wave amplitude and the velocity decreased after dilatancy started, and they kept decreasing even after the peak stress. In addition, the large nonlinear decrease in amplitude was associated with a rapid decrease in differential stress, whereas the rate of decrease in velocity remained almost constant. Thus, before the rapid decrease of differential stress, when both the amplitude and the velocity gradually decreased, open cracking was indicated to be dominant. Thereafter, shear cracking was indicated to become dominant in synchronization with the rapid decrease in differential stress. It is suggested that a main fault started to grow around the sample surface and then progressed into the sample interior; this corresponded to the rapid stress decrease. This fault acts as a strong scatterer for P waves that are parallel to the maximum compressive axis.
Strong ground motions from an Mj 6.1 inland crustal earthquake in Hokkaido, Japan: the 2004 Rumoi earthquake
Authors: Maeda Takahiro , Sasatani Tsutomu 
Published: August 2014

AbstractAn inland crustal earthquake (Mj6.1) occurred on December 14, 2004 in the northern part of Hokkaido, Japan. A large ground acceleration of 1127 cm/s2and a large pseudo-velocity response of over 100 cm/s were recorded at the nearest strong-motion station, HKD020, about 10 km from the hypocenter. This large ground motion is considered to be attributable to the source effect and the site effect. The site effect is investigated using the traditional spectral ratio technique and the theoretical evaluation based on the subsurface structure model. The results imply that the site effect has an insignificant effect on the large ground motion at HKD020. The source effect is investigated by constructing the source model that explains the broad-band strong-motion records at four stations around the epicenter using the empirical Green’s function method. The estimated source model satisfies the empirical relationship between the strong motion generation areas and the seismic moment for inland crustal earthquakes. The high-frequency level of the acceleration source spectrum is also consistent with the empirical relationship. These results suggest that this earthquake is a normal crustal event and that the large ground motion at HKD020 is mainly attributable to the source effect, short distance from the strong motion generation area and the forward directivity effect. Finally, the temporal change of the site response at HKD020 is examined using long duration records including the main shock and several aftershocks. The site response based on theS-wave horizontal-to-vertical spectral ratio method shows the nonlinearity for the main shock and an aftershock occurring about 20 s after the main shock. However, the site response shows linearity for other later aftershocks. This site response change is attributed to the difference in ground motion amplitude.
Remanence anisotropy effect on the palaeointensity results obtained from various archaeological materials, excluding pottery
Authors: Kovacheva Mary , Chauvin Annick , Jordanova Neli , Lanos Philippe , Karloukovski Vassil 
Published: August 2014

Abstract
The effect of magnetic anisotropy on the palaeointensity results has been evaluated in different materials, including samples from archaeological structures of various ages, such as baked clay from prehistoric domestic ovens or pottery kilns, burnt soil from ancient fires, and bricks and bricks or tiles used in the kiln’s construction. The remanence anisotropy was estimated by the thermoremanent (TRM) anisotropy tensor and isothermal remanence (IRM) tensor methods. The small anisotropy effect (less than 5%) observed in the palaeointensity results of baked clay from the relatively thin prehistoric oven’s floors estimated previously through IRM anisotropy was confirmed by TRM anisotropy of this material. The new results demonstrate the possibility of using IRM anisotropy evaluation to correct baked clay palaeointensity data instead of the more difficult to determine TRM anisotropy ellipsoid. This is not always the case for the palaeointensity results from bricks and tiles. The anisotropy correction to palaeointensity results seems negligible for materials other than pottery. It would therefore appear that the palaeointensity determination is more sensitive to the degree of remanence anisotropy P and the angle between the natural remanent magnetization (NRM) vector and the laboratory field direction, than to the angle between the NRM and the maximum axis of the remanence anisotropy ellipsoid (K
max).
Significant decreases in the geomagnetic indices in the ascending phase of Solar Cycle 24
Authors: Minamoto Yasuhiro , Taguchi Yosuke 
Published: August 2014

Abstract
Solar activity was quite low from January 2008 to February 2009, ever since the start of Solar Cycle 24. In 2008, the number of days in a year during which there were no sunspots was the fourth-largest since 1842. However, it is likely that the sunspot number would not have been able to reveal the solar inactivity in the beginning phase of cycle 24 because it hit the lower limit (zero) on more than two-thirds of the days of 2008. Geomagnetic data covers the longest span of time next to sunspot number, but its value has never reached that limit. The K-index, which is a geomagnetic index, from 2008 to the beginning of 2009, has been recorded at several observatories as being the smallest in the history of observation. The K
p-index, which characterizes the geomagnetic planetary activity, has also significantly decreased. Taking into account the relation between the K
p-index during the minimum phase of the solar cycle and sunspot numbers of the following maximum, it has been suggested that the peak solar activity in cycle 24 will be quite low. If solar activity in cycle 24 continues to be quiet, geomagnetic data are expected to be one of the key tools for monitoring space climate.
Wind observation around the tops of the midlatitude cirrus by the MU radar and Raman/Mie lidar
Authors: Yamamoto Masayuki K. , Kishi Toyohisa , Nakamura Takuji , Nishi Noriyuki , Yamamoto Mamoru , Hashiguchi Hiroyuki , Fukao Shoichiro 
Published: August 2014

Abstract
Using a 46.5-MHz atmospheric radar referred to as the MU radar (MUR) and a Raman/Mie lidar installed at the Shigaraki (34°51′N, 136°06′E), continuous wind motions around the tops of the midlatitude cirrus are described for the first time. The cloud system extended from the northeast to southwest (35°N-50°N) along the eastward-moving trough and passed over Shigaraki in the nighttime between 5–6 November 2004. Cloud-top altitude observed by the lidar was located at ∼10.6 km around 1900 LST 5 November, then gradually descended to ∼8.4 km around 0500 LST 6 November. The westerly wind observed by MUR with 12-min and 150-m resolutions showed a rapid increase with altitude around the cloud tops and was almost always larger than 25 m s−1 above ∼1 km higher than the cloud tops. Objective reanalysis showed that a subtropical jet whose core existed to the south of Shigaraki caused a synoptic-scale vertical increase in the westerly wind around the cloud tops. Radiosondes observed a significant vertical increase of potential temperature (greater than 4 K within several hundred meters) around the cloud tops. MUR successfully observed fine time and altitude variations of winds which showed a good correspondence with the descending cloud tops.
The seasonal and solar cycle variations of electron density gradient scale length during magnetically disturbed days: implications for Spread F
Authors: Manju G. , Devasia C. V. , Ravindran Sudha 
Published: August 2014

Abstract
The behaviour of electron density gradient scale length, L, around post-sunset hours during the magnetically disturbed days of the summer, winter and equinox seasons of solar maximum (2002) and minimum years (1995) has been studied, using ionosonde data of Trivandrum (8.5°N, 76.5°E, dip = 0.5°N) in the Indian longitude sector. The results indicate a clear seasonal and solar cycle variation in L. Seasonal variations of the maximum vertical drift of the F layer were also examined on these days. In particular, the seasonal variation of the Equatorial Spread F (ESF) during this period is examined in terms of the relative roles of L and the vertical drift of the F layer in the triggering of the collisional Rayleigh-Taylor instability. Our results on the clear-cut seasonal and solar cycle variation in L for disturbed days and its control of ESF occurrence are presented and discussed.
Measurement of atmospheric air-earth current density from a tropical station using improvised Wilson’s plate antenna
Authors: Anil Kumar C. P. , Panneerselvam C. , Nair K. U. , Jeeva K. , Selvaraj C. , Jeyakumar H. Johnson , Gurubaran S. 
Published: August 2014

Abstract
We have developed an experimental set-up to measure the atmospheric air-earth current (conduction current). Data obtained with the continuous measurements of Wilson’s plate are used to study of air-earth current density, with the aim of gaining an understanding of the experimental set-up’s response to different meteorological conditions, including fair-weather days. This paper is a part of the on-going Global Electric Circuit (GEC) studies from Tirunelveli (8.7°N, 77.8°E), a measurement site in the tropical and southern tip of the Indian peninsula. Attempts have been made in past few years to obtain the global signature in this region with this sensor, but on most of the occasions it has been impossible to obtain the global signature during fair-weather days. The data used for February–April, 2007 have the well-defined nature of this global signature, which is in agreement with the well-established classical Carnegie curve of GEC. This paper also deals with very important observations made at sunrise and during those hours when fog existed. It is noted that the resistivity of the atmosphere increased significantly with the onset of fog and later decreased as the fog disappeared, based on the measured value of conduction current density when compared with the electric field measured by horizontal passive wire antenna. Also, during fair-weather conditions, conduction current and electric field variations are similar because the conductivity during this period is more or less constant at this site. Observations made during different meteorological conditions, such as different wind speeds, humidities, and temperatures, are also discussed.
Effects of gravity data quality and spacing on the accuracy of the geoid in South Korea
Authors: Hong Chang-Ki , Kwon Jay Hyoun , Lee Bo Mi , Lee Jisun , Choi Yun Soo , Lee Suk-Bae 
Published: August 2014

Abstract
The effects of gravity data quality and spacing on the accuracy of the computed geoid are analyzed. The analysis is performed using simulated gravity data that accommodate the real gravity signal in South Korea. The reference geoid is generated using both simulated gravity data and digital terrain models (DTM), assuming that both data sets are errorless. By artificially controlling the gravity data quality and spacing, we are able to calculate and analyze the geoid errors. The results show that the current distribution of real gravity data in South Korea causes geoid errors, with the standard deviation being as much as 8 cm, and that these geoid errors are mainly caused by the distribution of gravity data rather than by the noise in the data. Areas showing large geoid errors are also clearly identified; these areas should be subjected to supplementary gravity surveying at data spacing smaller than 2 km to achieve a 5-cm level of geoid accuracy.
Crustal deformations associated with the great Sumatra-Andaman earthquake deduced from continuous GPS observation
Authors: Hashimoto Manabu , Choosakul Nithiwatthn , Hashizume Michio , Takemoto Shuzo , Takiguchi Hiroshi , Fukuda Yoichi , Fujimori Kunio 
Published: August 2014

Abstract
We analyzed continuous GPS data from more than 20 sites in Asia, Australia and islands in Indian Ocean in order to detect crustal deformations associated with the Sumatra-Andaman earthquake of December 26, 2004. Coseismic steps can be recognized at sites about 3,000 km away from the epicenter such as Kunming in south China, Quezon in Philippines, and Diego Garcia Island in central Indian Ocean. The largest displacement of about 26 cm is found at Phuket in Thailand about 600 km away from the epicenter, about twice as large as that at Sampari, the nearest site in northern Sumatra. These observations suggest that as large slip as 14 m occurred beneath the Nicobar Islands. Large postseismic displacements are observed at Phuket and Sampari after the mainshock, but the former is three times larger than the latter. This suggests that the spatial distribution of afterslip is different from the coseismic slip distribution. The temporal variation of postseismic displacements can be explained by a logarithmic function derived from rate-state dependent friction law with short characteristic time. The area where coseismic displacements from the Nias earthquake of March 28, 2005 are detected is much smaller than that from the December mainshock, but displacement at Sampari is larger than that during the mainshock. These displacements suggest less than 4 m slip on a shallow dipping thrust fault and resultant moment release is smaller than that estimated from seismological data. Finally, total moment released by afterslip amounts to 3.83 × 1022 Nm which is equivalent to Mw 8.99 for about five months, including the afterslip for the Nias earthquake.
The 2004 Indian Ocean tsunami: Tsunami source model from satellite altimetry
Authors: Hirata Kenji , Satake Kenji , Tanioka Yuichiro , Kuragano Tsurane , Hasegawa Yohei , Hayashi Yutaka , Hamada Nobuo 
Published: August 2014

AbstractSatellite altimetry measurements of sea surface heights for the first-time captured the Indian Ocean tsunami generated from the December 2004 great Sumatra earthquake. Analysis of the sea surface height profile suggests that the tsunami source, or the seafloor deformation, of the great earthquake propagated to the north at an extremely slow speed of less than 1 km/sec on average for the entire 1300-km-long segment along the northern Sumatra-Nicobar-Andaman Trench. The extremely slow propagation speed produces a very long duration of tens minutes, longer than earthquake source duration estimated (480–500 sec) from short-periodP-wave radiation. The satellite altimetry data requires a total seismic moment of 9.86 × 1022Nm (Mw=9.3). This estimate is approximately 2.5 times larger than the value from long-period surface wave analysis but nearly the same as that from the ultra-long-period normal mode study. The maximum amount of slip (∼30 m) is identified in an offshore region closest to the northern most part of Sumatra where the largest tsunami run-up heights were observed.
The Great Tsunami of 26 December 2004: A description based on tide-gauge data from the Indian subcontinent and surrounding areas
Authors: Nagarajan B. , Suresh I. , Sundar D. , Sharma R. , Lal A. K. , Neetu S. , Shenoi S. S. C. , Shetye S. R. , Shankar D. 
Published: August 2014

Abstract
The Great Tsunami of 26 December 2004 is described using data from seven tide gauges in India and others from surrounding areas in the Indian Ocean. The tsunami struck the Indian east coast around 0330 UTC. The amplitude was 2 m above the tide at Chennai, Paradip, and Colombo. The east coast of India (and of Sri Lanka) was hit shortly after high tide; Tuticorin and Colombo, however, were hit shortly after low tide. The tsunami wave propagated northward along the Indian west coast. All these gauges are to the west of the earthquake zone and the detided sea levels show first a rise in sea level with the arrival of the tsunami, and then a sharp decrease. Spectral and wavelet analysis of the detided series show that the maximum amplitude was at a period of 35–45 minutes, with another maximum around 20 minutes. Along the Indian east coast, however, there is another broad peak between 1–2 hours within the first few hours after the first tsunami wave.
Tsunami heights and damage along the Myanmar coast from the December 2004 Sumatra-Andaman earthquake
Authors: Satake Kenji , Aung Than Tin , Sawai Yuki , Okamura Yukinobu , Win Kyaw Soe , Swe Win , Swe Chit , Swe Tint Lwin , Tun Soe Thura , Soe Maung Maung , Oo Thant Zin , Zaw Saw Htwe 
Published: August 2014

Abstract
The tsunami heights from the 2004 Sumatra-Andaman earthquake were between 0.4 and 2.9 m along the Myanmar coast, according to our post tsunami survey at 22 sites in Ayeyarwaddy Delta and the Taninthayi coast. Interviews to coastal residents indicate that the tsunami heights were lower than high tide level in rainy season, probably by storm surge. They also testified that the arrival times were between 2 and 5.5 hours after the earthquake but the reliability may be low because nobody felt ground shaking. Much smaller tsunami than the neighboring Thai coast, where the tsunami heights were 5 to 20 m, explains relatively slighter tsunami damage in Myanmar; the casualties were reported as 71, compared to about 8300 in Thailand. The smaller tsunami was probably due to the fact that the main tsunami source did not extend to Andaman Islands. The tsunami travel times and maximum heights computed from a 700 km long source are basically consistent with the observations. For a nearby tsunami source, the tsunami hazard would be more significant in Myanmar, because coastal houses are unprotected for tsunamis and no infrastructure exists to disseminate tsunami warning information.
Innere und äußere Kreise
Authors: Siems Renke 
Published: August 2014

Zusammenfassung:
Der Beitrag rekonstruiert prominente bibliothekspolitische Beiträge der 1980er Jahre vor dem Hintergrund des unmittelbar danach einsetzenden digitalen Wandels und fragt danach, wie die seinerzeit kritisierten Strukturen und Mentalitäten bis heute aktuelle Problemlagen konturieren und die Rolle von Bibliotheken in digitalen Informationsumwelten (mit-)bestimmen.
Agenda 2020 für die Wildauer Hochschulbibliothek
Authors: Seeliger Frank 
Published: August 2014

Zusammenfassung:
Die Wildauer Hochschulbibliothek hatte sich 2013 trotz guter „Bilanzen“ entschlossen, wegen der auf sie kommenden Unwägbarkeiten und Herausforderungen ein strategisches wie machbares Konzept zu erarbeiten. Dieses soll bis zum Jahr 2020 umgesetzt sein und die Entscheider im Umfeld der Hochschulbibliothek über ihre Ziele und Meilensteine verständigen. Die Stakeholder sollen über die schriftliche Fixierung ebenfalls dafür gewonnen und begeistert werden. Das ambitionierte Werk, die Agenda 2020, startete damit, dass das Bibliotheksteam fern vom Alltag an einem ungewöhnlichen, aber inspirierenden Ort in Klausur ging. Ein Segeltörn zu Pfingsten 2013 gab den Start für die Agenda 2020. Sieben Themenfelder konnten identifiziert und mit konkreten Vorhaben formuliert werden.