bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural interpretation of the Tuzgolu and Haymana Basins, Central Anatolia, Turkey, using seismic, gravity and aeromagnetic data
Authors: Aydemir Attila , Ates Abdullah 
Published: August 2014

Abstract
The Tuzgolu Basin is the largest basin in Central Anatolia. It is connected to the Haymana Basin by a small channel-shaped basin called the Tersakan Basin. The study area has smooth topography with a stable young sedimentary cover and limited outcrop zones, but displays a complex geology with intense active tectonism and poor seismic quality beneath the surface. In the study reported here an attempt was made to determine the subsurface structure of the basement by three-dimensional modelling of gravity data. The seismic and magnetic data were also integrated with the available geological data to check the modelling results. The modelling results suggest that the deeper parts of the Haymana Basin are located to the east of Haymana city centre, at a maximum depth of 8 km, with the exception of the depression to the north, which is located 25 km northwest of Bala city centre at a maximum depth of 10 km. The channel-shaped Tersakan Basin (connecting the Haymana and Tuzgolu Basins) is located west of Lake Tuzgolu, and the deepest part of this basin is approximately 5.5 km. The Tuzgolu Basin has three major depressions: (1) the Southern Aksaray Depression, which is covered by younger volcanic rocks, is the largest but in general the least explored area; (2) the Eregli Depression; (3) the Sultanhani Depression. Almost all of these depressions have an average depth of 8 km; however, some of the deeper segments are at a depth of approximately 12–13 km. Our results suggest the possibility of hydrocarbon potential in these basins.
Aeromagnetic data analysis for the identification of concealed uranium deposits: a case history from Singhbhum uranium province, India
Authors: Anand S. P. , Rajaram Mita 
Published: August 2014

Abstract
Aeromagnetic data over a part of the Singhbhum uranium province, India, within the framework of ‘Operation Hard Rock’ have been analyzed. The aeromagnetic anomaly map, its analytic signal amplitude, the Euler solutions and apparent susceptibility map helped in identifying the nature and depth of the magnetic sources in the study region. The Singhbhum Shear Zone is clearly delineated. The location of the mined uranium deposits coincide with the shallow magnetic sources. The present study also identified distinctive magnetic sources between the Dalma Volcanics and the Chotanagpur Granitic Gneissic Complex that suggest the presence of a sub-surface shear. The magnetic sources in this newly identified shear zone lie at a depth of 200 m and depict a similar magnetic signature and susceptibility as those of the Singhbhum Shear Zone where uranium is being mined. This shear could be the subsurface contact between high-grade metamorphic rocks (amphibolite facies) to the north and the greenschist facies low-grade metamorphics to the south. This shear zone, also characterized by radiometric anomalies, possibly indicates a zone of concealed uranium deposit that can be explored in the future. The present analysis shows the importance of aeromagnetic surveys and its utility in exploration for concealed mineral deposits.
Magnetostratigraphy of the lower Cretaceous strata in Tlayúa Quarry, Tepexi de Rodriguez, State of Puebla, Mexico
Authors: Benammi Mouloud , Alvarado-Ortega Jesus , Urrutia-Fucugauchi Jaime 
Published: August 2014

Abstract
A stratigraphic sequence of magnetic polarity reversals consisting of nine magnetozones is recognized in Early Cretaceous sedimentary strata in the Tlayúa Quarry of Tepexi de Rodriguez, state of Puebla. Combined with biostratigraphic age assignments using ammonites that apparently belonging to the Albian, the geomagnetic polarity sequence can be correlated with the middle part of chron C34n (C34n.1n-C34n.2n chrons, with an age of 100–105 Myr), the Cretaceous long normal interval. The magnetic properties and characteristic remanence of magnetization are dominated by soft and hard coercivity magnetic minerals. Rock-magnetic properties and a positive reversal test suggest that remanence is primary. The section displays both reverse and normal polarities with mean directions: D=344.9°, I=32.4°, k=21, a95=4.2° and D=149.4°, I=−36.6°, k=17, a95=8.7°, respectively. Comparison with the North American apparent polar wander path indicates tectonic stability of the region since the Cretaceous.
Low-latitude paleosecular variation and the time-averaged field during the late Pliocene and Quaternary—Paleomagnetic study of the Michoacan-Guanajuato volcanic field, Central Mexico
Authors: Conte-Fasano G. , Urrutia-Fucugauchi J. , Goguitchaichvili A. , Morales-Contreras J. 
Published: August 2014

AbstractWe report paleomagnetic, rock magnetic, and paleointensity studies for 24 volcanic lava flows from the Michoacan-Guanajuato volcanic field (MGVF), erupted between 2.27 Ma to present according to available radiometric ages and historic records. The MGVF located in the central-western sector of the Plio-Quaternary Trans-Mexican volcanic belt is mainly composed by cinder cones and shield volcanoes. Rock magnetic experiments show remanence is carried in most cases by Ti-poor titanomagnetites, resulting from oxy-exsolution of original titanomagnetites during flow cooling. Unblocking temperature spectra and high coercivities point to “small” pseudo-single domain grains for the titanomagnetites. Single component, linear vector plots are obtained after alternating field and thermal demagnetization. Seven flows yield reverse polarity magnetization while sixteen flows are normally magnetized. The overall mean paleodirection obtained (with 14 flows normal and 6 flows reverse) is I=28.4°, D=357.9°, k=21, α95=7.3°, with a paleomagnetic pole position ofPlat=85.7°,Plong= 104.5°, K=27, A95=6.4°. The paleodirection is undistinguishable from expected Plio-Quaternary paleodirections derived from reference poles for the North American polar wander curve, and previously reported paleodirections for central Mexico. Paleointensity experiments give high quality results for only twelve samples from two flows with mean values of 7.3 and 8.1 × 1022Am2, which are close to present geomagnetic field intensity. The combination of new MGVF directional results with currently available paleomagnetic data from central Mexico yield angular dispersion estimates ofSF= 15.4 withSU= 19.6 andSL= 12.7, which are in agreement with the latitude-dependent PSV model of McFaddenet al.(1988, 1991) for the last 5 Ma, and show no significant inclination anomaly.
Archaeomagnetic investigation of oriented pre-Columbian lime-plasters from Teotihuacan, Mesoamerica
Authors: Soler-Arechalde A. M. , Sánchez F. , Rodriguez M. , Caballero-Miranda C. , Goguitchaishvili A. , Urrutia-Fucugauchi J. , Manzanilla L. , Tarling D. H. 
Published: August 2014

Abstract
Results of an archaeomagnetic study of two excavation field seasons at the Xalla and Teopancazco residential areas of the ancient Prehispanic city of Teotihuacan, Central Mexico are reported. One-hundred and fifty three oriented samples of lime-plasters from the two archaeological sites were collected for the study. NRM directions are reasonably well grouped. Alternating field demagnetization shows single or two-component magnetizations. Rock magnetic measurements point to fine-grained titanomagnetites with pseudo-single domain behaviour. Characteristic site mean directions from both sites are correlated to the available palaeosecular variation curve for Mesoamerica. The mean directions obtained from Xalla site point to average dates of 550 AD±25 years that matches with the documented ‘Big Fire’ of Teotihuacan (AD 575). Two consecutive construction levels at Teopancazco were estimated as AD 250–350 and AD 350–425 respectively.
Earthquake probability based on multidisciplinary observations with correlations
Authors: Imoto Masajiro 
Published: August 2014

Abstract
A number of researchers have formulated earthquake probabilities based on precursory anomalies of multidisciplinary observations in which the underlying assumption is that the occurrence of one precursory anomaly is independent from those of other kinds of anomalies. Observations were classified into two groups, those events followed by an earthquake and those that were not, and the ratio of observed precursors in both groups was taken into consideration. In the present report, recent advances in statistical seismology are considered within the framework of these earthquake probabilities, and the formulations are extended to cases in which precursory anomalies are observed as continuous measurements. The effects originating from mutual correlations between two precursory anomalies are also considered. It is assumed that observed values of each discipline follow a normal distribution, either as a group of observations followed by an earthquake (conditional density distribution) or as a group of observations not followed by an earthquake (background density distribution). Special attention is given to the case in which two kinds of observations are correlated in the conditional density distribution but not in the background density distribution. The results obtained are compared with cases in which the observations are independent of each other in both distributions. The geometrical mean of the probability gain is greater in the correlated case than in the independent case and becomes infinitely large when the absolute value of the correlation coefficient approaches one. This finding enables a wider application of earthquake probability than has been previously possible based on multidisciplinary observations.
Kinematics of the East Anatolian Fault Zone between Turkoglu (Kahramanmaras) and Celikhan (Adiyaman), eastern Turkey
Authors: Yilmaz Huseyin , Over Semir , Ozden Suha 
Published: August 2014

Abstract
In this study we determined the stress regime acting along the East Anatolian Fault Zone between Turkoglu (Kahramanmaras) and Celikhan (Adiyaman), from the Neocene to present-day, based on the inversion of striations measured on faults and on the focal mechanisms of earthquakes having magnitudes greater than 5.0. The inversions yield a strike-slip stress regime with a reverse component (i.e., transpression) operative in the Neocene to present with a consistent N-to NW-trending σ1 axis 156 ± 11° and an E- to NE-trending σ3 axis, 67 ± 9°σ3, producing left-lateral motion along the East Anatolian Fault Zone. The inversions of focal mechanisms yield a strike-slip stress deviator characterized by an approximately N-S (N89°W)-trending σ1 and an approximately E-W (N89°E)-trending σ3 axis. Both the kinematic analysis and structural observations indicate that the stress regime operating in the study area has had a transpressional character, giving rise to the Mio-Pliocene compressive structures (reverse faults, thrusts and folds) observed in the study area. Field observations allow estimation of a Pliocene age for the strike-slip East Anatolian Fault Zone.
Assessing potential seismic activity in Vrancea, Romania, using a stress-release model
Authors: Imoto Masajiro , Hurukawa Nobuo 
Published: August 2014

Abstract
Over the last 500 years, an average of five intermediate-depth earthquakes of Mw = 7 and larger have occurred during each 100-year period in Vrancea, Central Romania. We have therefore attempted to assess the long-term seismic hazards in Vrancea using a stress-release (SR) model which models the elastic rebound theory in a stochastic process. The hypocenter catalog, ROMPLUS, provided by the National Institute for Earth Physics (NIEP), was adopted for the study. We only used data on earthquakes located in Vrancea and applied the SR-model to data sets of earthquakes with a magnitude of 7.0 and larger for three different time periods. Renewal models, such as the Brownian and Weibull model, were also applied to the same data set, but these did not perform as well as the SR-model. The SR-model can assess future earthquake probability and has identified that the probability of an earthquake occurring in Vrancea in a 5-year period exceeds 40% by the end of this decade.
Investigation of the earthquake sequence off Miyagi prefecture with historical seismograms
Authors: Kanamori Hiroo , Miyazawa Masatoshi , Mori Jim 
Published: August 2014

Abstract
We investigated the old seismograms of several earthquakes which occurred offshore of Miyagi prefecture in 1933 (June 18, 21:37 UT), 1936 (Nov. 2, 20:45 UT), 1937 (July 26, 19:56 UT), 1978 (June 12, 08:14 UT), and 2005 (Aug. 16, 02:46 UT). A characteristic earthquake model for the sequence of the 1936, 1978, and several other earlier events is the basis of the recent forecast by the Earthquake Research Committee (2003) that “The probability of the occurrence of another similar earthquake in the next 30 years is 99%”. To assess the validity of the characteristic earthquake model, we compared the waveforms, size and other characteristics of these earthquakes recorded at Pasadena, DeBilt, Abuyama, Aso, Weston, Strasbourg, and Christchurch. We conclude that (1) The 1978 event is 3 to 4.5 times larger (in seismic moment) than the 2005 event; (2) The 1936 and the 2005 events are about the same size and are fairly close in location; (3) The 1937 event is smaller than the 1936 event, and is significantly deeper, possibly as deep as 90 km. In contrast, the 1933 event is significantly shallower than the 1936 event. The differences between these events are too large to justify the use of a simple characteristic earthquake model for the probabilistic forecast. The seismic slip rate in this area and along the adjacent subduction zone to the south is about 1/4 of the plate convergence rate, which has an important implication for the long-term seismic hazard in this area.The 2005 West Off Fukuoka Prefecture earthquake caused serious damage to and on Genkai Island as well as to downtown Fukuoka City. There were no strong motion instruments on the island, therefore no one knows how the strong ground motion occurred during the mainshock. The ground motion simulation on Genkai Island is very important to our understanding of earthquake damage at the near-source region. We have conducted an aftershock observation on the island in order to verify site amplification due to steep topography and to record aftershocks for reproducing ground motion during the mainshock by the empirical Green’s function method. The observed records of aftershocks show small variations in the input motions in the island, indicating that the amplification due to the topography seems to be small below 2 Hz. We first estimated the strong motion generation area for the mainshock using the observation records at stations surrounding the source region. We then carried out broadband ground motion simulation on Genkai Island by using the aftershock records as empirical Green’s functions. The simulated ground velocities exceed 1 m/s with a dominant period of 1–2 s due to the forward rupture directivity, and the instrumental seismic intensity reaches 6.6.
Preparatory process reflected in seismicity-pattern change preceding the M=7 earthquakes off Miyagi prefecture, Japan
Authors: Matsumura Shozo 
Published: August 2014

Abstract
Two M=7 interplate earthquakes recently occurred off Miyagi prefecture, northeastern Japan. These belong to a new sequence of earthquake series. The occurrence of this sequence was forewarned by the government, based primarily on a statistical approach utilizing historical records. Such a process, however, does not account for the present on-going status in the assessment. During the stage when stress approaches a critical level, there is a possibility of stress redistribution caused by a quasi-static slip, which will be reflected in a temporal change in seismic activity. Delineating a spatial map of the seismic-activity rate changes in the seismogenic zone off Miyagi prefecture, we found that there was an activation of microseismicity in the rupture zones several months prior to both M=7 earthquakes. This was interpreted as evidence of a preparatory process preceding each M=7 earthquake, during which a quasi-static slip progressed, driving stress redistribution and resulting in stress concentration on asperities of these earthquakes.
Shear wave polarization anisotropy in and around the focal region of the 2005 West off Fukuoka Prefecture earthquake
Authors: Watanabe Atsushi , Matsumoto Satoshi , Matsushima Takeshi , Uehira Kenji , Matsuwo Norimichi , Shimizu Hiroshi 
Published: August 2014

Abstract
Crustal shear wave polarization anisotropy is caused by the alignment of vertical microcracks. Leading shear wave polarization directions (LSPDs) are presumed to be consistent with the maximum horizontal compressional axis in many cases. We analyzed shear wave polarization anisotropy in and around the focal region of the 2005 West off Fukuoka Prefecture earthquake. Almost all of the LSPDs are oriented in the E-W direction, which is consistent with the maximum horizontal compressional axis inferred from the mechanism of the main shock. These E-to W-oriented LSPDs are caused by the alignment of stress-induced microcracks. Crack densities at most stations are estimated to be 0.02. Little spacial stress variation around focal region is suspected
Empirical Green’s function simulation of broadband ground motions on Genkai Island during the 2005 West Off Fukuoka Prefecture earthquake
Authors: Miyake Hiroe , Tanaka Yasuhisa , Sakaue Minoru , Koketsu Kazuki , Ishigaki Yuzo 
Published: August 2014

Abstract
The 2005 West Off Fukuoka Prefecture earthquake caused serious damage to and on Genkai Island as well as to downtown Fukuoka City. There were no strong motion instruments on the island, therefore no one knows how the strong ground motion occurred during the mainshock. The ground motion simulation on Genkai Island is very important to our understanding of earthquake damage at the near-source region. We have conducted an aftershock observation on the island in order to verify site amplification due to steep topography and to record aftershocks for reproducing ground motion during the mainshock by the empirical Green’s function method. The observed records of aftershocks show small variations in the input motions in the island, indicating that the amplification due to the topography seems to be small below 2 Hz. We first estimated the strong motion generation area for the mainshock using the observation records at stations surrounding the source region. We then carried out broadband ground motion simulation on Genkai Island by using the aftershock records as empirical Green’s functions. The simulated ground velocities exceed 1 m/s with a dominant period of 1–2 s due to the forward rupture directivity, and the instrumental seismic intensity reaches 6.6.
Electrostatic quasi-monochromatic waves in the downstream region of the Earth’s bow shock based on Geotail observations
Authors: Shin Koichi , Kojima Hirotsugu , Matsumoto Hiroshi , Mukai Toshifumi 
Published: August 2014

Abstract
Geotail plasma wave observations show the existence of intense electrostatic quasi-monochromatic (EQM) waves in the downstream region of the Earth’s bow shock. They oscillate parallel to the ambient magnetic field and appear at frequencies between the electron plasma and ion plasma frequencies. Although these waves have been believed to be Doppler-shifted ion acoustic waves, the typical plasma parameters observed in the downstream region do not support the generation conditions for ion acoustic waves. In this paper, the existence of cold electron beam-like components accompanying EQM waves is considered based on waveform and statistical analyses. Linear dispersion analyses using realistic plasma parameters revealed that the cold electron beams cause destabilization of electron acoustic waves at frequencies consistent with those of observed EQM waves. The results of observations and linear analyses suggest that EQM waves are generated by the destabilization of the electron acoustic mode.
Tectonic history of Europa: Coupling between internal evolution and surface stresses
Authors: Kimura Jun , Yamagishi Yasuko , Kurita Kei 
Published: August 2014

Abstract
A stress history in the ice shell of Europa is presented. Europa’s surface is ubiquitous in extensional tectonic features such as banded terrains. These surface features suggest that the surface may have been fractured and extended due to tensional stress, and various origins for such stresses have been proposed. We have focused on the solidification of the liquid water layer and the accompanying volume change as one of the dominant sources for such stresses. To estimate the stress state in the ice shell, we first performed numerical simulations of the thermal history. Based on the resulting structural evolution, we calculated stresses in the viscoelastic ice shell due to the solidification of the liquid layer. Europa’s liquid layer solidifies slowly and may partially survive at present, and its solidification induces sufficient tensional stress to drive extensional tectonic activity. Consequently, we propose the tectonic scenario that the volume change due to phase change develops the basic amplitude of the stress, while tidal forces work as a trigger to fracture the surface.
Variations in the total electron content near the crest of the equatorial ionization anomaly during the November 2004 geomagnetic storm
Authors: Dashora Nirvikar , Pandey R. 
Published: August 2014

Abstract
Space weather studies using a Global Positioning System (GPS) receiver are underway near the crest of the equatorial ionization anomaly (EIA), at Udaipur (MLAT 16.0°N), India. These studies are probably, the first of its kind in the Indian zone near the crest of the EIA. Results for the geomagnetic storm that occurred during November 2004 are presented. Drastic variations in the total electron content (TEC) have been observed as a result of this storm. It is inferred that the reduced levels of TEC following the storm may be attributed to the weakened equatorial plasma fountain due to the disturbance dynamo fields.
First results from the Penn State Allsky Imager at the Arecibo Observatory
Authors: Seker Ilgin , Mathews John D. , Wiig Johannes , Gutierrez Paloma F. , Friedman Jonathan S. , Tepley Craig A. 
Published: August 2014

Abstract
The Penn State Allsky imager (PSASI), a user-owned-public-access (UOPA) instrument installed at Arecibo Observatory (AO: 18.3°N, 66.75°W; altitude: 350 m a.s.l.; L = 1.43 at 300 km; dip angle: 46°; geomagnetic coordinates: 29°N, 5.5°E), is a CCD-based high-resolution allsky optical imager that has been collecting ionospheric airglow data at night since May 2003. The computer controlled six-position filter wheel is equipped with three filters at 630 nm (red), 557.7 nm (green), and 777.4 nm (near-IR), respectively, which correspond to ionosphere-related oxygen emissions. The imager data, taken for more than 3.5 years now, is being used to study various ionospheric processes, such as mapped equatorial spread-F plumes, E-region gravity waves, among other, in conjunction with the AO incoherent scatter radar (ISR), mesosphere and lower thermosphere (MLT) metals lidar, and other instruments, including microbarographs. Data availability and quality as well as specific airglow events on both small/large time/spatial scales are examined, categorized, and made freely available at a data-server website. Our goal here is to briefly review the airglow science enabled by allsky imaging at AO, to describe the instrument and the data-collection methodology, and to present some of the significant results, including airglow events that correspond to ISR results.