Seismic Hazard and Loss Estimation for Central America   总被引：2，自引：2，他引：2  

Yong  Chen  Ling  Chen  Güendel  Federico  Kulhánek  Ota  Juan  Li 《Natural Hazards》2002,25(2):161-175

A new methodology of seismic hazard and loss estimation has been proposed by Chen et al. (Chen et al., 1998; Chan et al., 1998) for the study of global seismic risk. Due to its high adaptability for regions of different features and scales, the methodology was applied to Central America. Seismic hazard maps in terms of both macro-seismic intensity and peak ground acceleration (PGA) at 10% probability of exceedance in 50 years are provided. The maps are all based on the global instrumental as well as historical seismic catalogs and available attenuation relations. Employing the population-weighted gross domestic product (GDP) data, the expected earthquake loss in 50 years for Central America is also estimated at a 5' latitude × 5' longitude resolution. Besides the seismic risk index, a measure of the relative loss or risk degree is calculated for each individual country within the study area. The risk index may provide a useful tool to help allocations of limited mitigation resources and efforts for the purpose of reduction of seismic disasters. For expected heavy loss locations, such as the Central American capital cities, earthquake scenario analysis is helpful in providing a quick overview of loss distribution assuming a major event occurs there. Examples of scenario analysis are given for San Jose, capital of Costa Rica, and Panama City, capital of Panama, respectively.  相似文献   

Neutron Activation Analysis of Nine GSJ Sedimentary Rock Reference Samples     

Naomi AOTA  Yutaka MIYAMOTO  Sakae KOSANDA  Yasuji OURA  Toshiyuki OKUI  Koh SAKAMOTO 《Geostandards and Geoanalytical Research》1994,18(2):185-193

Nine rock reference samples "Sedimentary rock series" issued by the Geological Survey of Japan (GSJ) were analysed for up to 31 elements by neutron activation analysis (NAA); 14MeV-NAA for Si and Al, fission track method for U, radiochemical and instrumental NAA for rare-earth elements, and instrumental NAA for the remaining elements, with reactor neutrons for the latter three. The present results are compared with reported values.  相似文献   

Seismodynamics of Sweden deduced from earthquake focal mechanisms   总被引：3，自引：0，他引：3  

Ronald Arvidsson  Ota Kulhanek 《Geophysical Journal International》1994,116(2):377-392

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Source processes of the 1981 Gulf of Corinth earthquake sequence from body-wave analysis     

Won-Young Kim  Ota Kulhnek  Klaus Meyer 《Tectonophysics》1985,118(3-4)

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Newly found Tunglo Active Fault System in the fold and thrust belt in northwestern Taiwan deduced from deformed terraces and its tectonic significance     

Yoko Ota  Yu-nong Nina Lin  Yue-Gau Chen  Hui-Cheng Chang  Jih-Hao Hung 《Tectonophysics》2006,417(3-4):305-323

We found active faults in the fold and thrust belt between Tunglo town and the Tachia River in northwestern Taiwan. The surface rupture occurred in 1999 and 1935 nearby the study area, but no historical surface rupture is recorded in this area, suggesting that the seismic energy has been accumulated during the recent time. Deformed fluvial terraces aid in understanding late Quaternary tectonics in this tectonically active area. This area contains newly identified faults that we group as the Tunglo Fault System, which formed after the area's oldest fluvial terrace and appears at least 16 km long in roughly N–S orientation. Its progressive deformations are all recorded in associated terraces developed during the middle to late Quaternary. In the north, the system consists of two subparallel active faults, the Tunglo Fault and Tunglo East Fault, striking N–S and facing each other from opposite sides of the northward flowing Hsihu River, whose course may be controlled by interactions of above-mentioned two active faults. The northern part of the Tunglo Fault, to the west of the river, is a reverse fault with upthrown side on the west; conversely the Tunglo East Fault, to the east, is also a reverse fault, but with upthrown side on the east. Both faults are marked by a flexural scarp or eastward tilting of fluvial terraces. Considering a Quaternary syncline lies subparallel to the east of this fault system, the Tunglo Fault might be originated as a bending moment fault and the Tunglo East Fault as a flexural slip fault. However, they have developed as obvious reverse faults, which have progressive deformation under E–W compressive stress field of Taiwan. Farther south, a west-facing high scarp, the Tunglo South Fault, strikes NNE–SSW, oblique to the region's E–W direction of compression. Probably due to the strain partitioning, the Tunglo South Fault generates en echelon, elongated ridges and swales to accommodate right-lateral strike–slip displacement. Other structures in the area include eastward-striking portion of the Sanyi Fault, which has no evidence for late Quaternary surface rupture on this fault; perhaps slip on this part of Sanyi Fault ceased when the Tunglo Fault System became active.  相似文献   

Beyond the skin colour of racism     

Naomi  Standen 《The Geographical journal》2007,173(4):392-393

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Progressive metamorphism of the Taitao ophiolite; evidence for axial and off-axis hydrothermal alterations     

Takazo Shibuya  Tsuyoshi Komiya  Ryo Anma  Tsutomu Ota  Soichi Omori  Yoshiaki Kon  Shinji Yamamoto  Shigenori Maruyama 《Lithos》2007,98(1-4):233-260

We estimated metamorphic conditions for the  6 Ma Taitao ophiolite, associated with the Chile triple junction. The metamorphic grade of the ophiolite, estimated from secondary matrix minerals, changes stratigraphically downwards from the zeolite facies, through the prehnite–actinolite facies, greenschist facies and the greenschist–amphibolite transition, to the amphibolite facies. The metamorphic facies series corresponds to the low-pressure type. The metamorphic zone boundaries are subparallel to the internal lithological boundaries of the ophiolite, indicating that the metamorphism was due to axial hydrothermal alteration at a mid-ocean ridge.

Mineral assemblages and the compositions of veins systematically change from quartz-dominated, through epidote-dominated, to prehnite-dominated with increasing depth. Temperatures estimated from the vein assemblages range from  230 °C in the volcanic unit to  380 °C at the bottom of the gabbro unit, systematically  200 °C lower than estimates from the adjoining matrix minerals. The late development of veins and the systematically lower temperatures suggest that the vein-forming alteration was due to off-axis hydrothermal alteration.

Comparison between the Taitao ophiolite with its mid-ocean ridge (MOR) affinity, and other ophiolites and MOR crusts, suggests that the Taitao ophiolite has many hydrothermal alteration features similar to those of MOR crusts. This is consistent with the tectonic history that the Taitao ophiolite was formed at the South Chile ridge system near the South American continent (Anma, R., Armstrong, R., Danhara, T., Orihashi, Y. and Iwano, H., 2006. Zircon sensitive high mass-resolution ion microprobe U–Pb and fission-track ages for gabbros and sheeted dykes of the Taitao ophiolite, Southern Chile, and their tectonic implications. The Island Arc, 15(1): 130–142).  相似文献   

Changes in paleoseismic studies of active faults in Japan since the 1995 Kobe earthquake     

Yoko Ota 《Journal of Geodynamics》2000,29(3-5)

This paper discusses recent progress of onshore active faults studies in Japan, especially since the 1995 destructive Kobe earthquake, when the number of trenching studies, which are essential for the reconstruction of onshore paleoearthquakes, has rapidly increased. The timing and repeat interval of paleoearthquakes are here reviewed for the Miura Peninsula, south of Tokyo and the Awaji Island and Kobe-Osaka area, in central Japan, where trenching have been carried out very intensively in the last few years.  相似文献   

Experimental investigation on cohesionless sandy bank failure resulting from water level rising   总被引：1，自引：1，他引：0  

Ryosuke Arai  Kazuyuki Ota  Takahiro Sato  Yasushi Toyoda 《国际泥沙研究》2018,33(1):47-56

In the last decade, sediment replenishment forming cohesionless sandy banks below dams has become an increasingly common practice in Japan to compensate for sediment deficits downstream. The erosion process of the placed cohesionless sediment is a combination of lateral toe-erosion and the following mass failure. To explore cohesionless bank failure mechanisms, a series of experiments was done in a soil tank using a compacted sandy soil mass exposed to an increasing water level. Two types of uniform sand(D_(50) = 0.40 mm and 0.17 mm) and two bank heights(50 cm and 25 cm) were used under the condition of a constant bank slope of 75°. The three dimensional(3D) geometry of the bank after failure was measured using a handheld 3D scanner. The motion of bank failure was captured using the particle image velocimetry(PIV) technique, and the matric suction was measured by tensiometers. The compacted sandy soil was eroded by loss of matric suction accompanying the rise in water level which subsequently caused rotational slide and cantilever toppling failure due to destabilization of the bank. The effect of erosion protection resulting from the slumped blocks after these failures is discussed in the light of different failure mechanisms. Tensile strength is analyzed by inverse calculation of cantilever toppling failure events. The tensile strength had non-linear relation with degree of saturation and showed a peak.The findings of the study show that it is important to incorporate the non-linear relation of tensile strength into stability analysis of cantilever toppling failure and prediction of tension crack depth within unsaturated cohesionless banks.  相似文献   

A QGIS Plugin Based on the PaPRIKa Method for Karst Aquifer Vulnerability Mapping     

Chloé Ollivier  Yoann Lecomte  Konstantinos Chalikakis  Naomi Mazzilli  Charles Danquigny  Christophe Emblanch 《Ground water》2019,57(2):201-204

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