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11.
Kenji Satake Yuichi Nishimura Purna Sulastya Putra Aditya Riadi Gusman Haris Sunendar Yushiro Fujii Yuichiro Tanioka Hamzah Latief Eko Yulianto 《Pure and Applied Geophysics》2013,170(9-10):1567-1582
The 2010 Mentawai earthquake (magnitude 7.7) generated a destructive tsunami that caused more than 500 casualties in the Mentawai Islands, west of Sumatra, Indonesia. Seismological analyses indicate that this earthquake was an unusual “tsunami earthquake,” which produces much larger tsunamis than expected from the seismic magnitude. We carried out a field survey to measure tsunami heights and inundation distances, an inversion of tsunami waveforms to estimate the slip distribution on the fault, and inundation modeling to compare the measured and simulated tsunami heights. The measured tsunami heights at eight locations on the west coasts of North and South Pagai Island ranged from 2.5 to 9.3 m, but were mostly in the 4–7 m range. At three villages, the tsunami inundation extended more than 300 m. Interviews of local residents indicated that the earthquake ground shaking was less intense than during previous large earthquakes and did not cause any damage. Inversion of tsunami waveforms recorded at nine coastal tide gauges, a nearby GPS buoy, and a DART station indicated a large slip (maximum 6.1 m) on a shallower part of the fault near the trench axis, a distribution similar to other tsunami earthquakes. The total seismic moment estimated from tsunami waveform inversion was 1.0 × 1021 Nm, which corresponded to Mw 7.9. Computed coastal tsunami heights from this tsunami source model using linear equations are similar to the measured tsunami heights. The inundation heights computed by using detailed bathymetry and topography data and nonlinear equations including inundation were smaller than the measured ones. This may have been partly due to the limited resolution and accuracy of publically available bathymetry and topography data. One-dimensional run-up computations using our surveyed topography profiles showed that the computed heights were roughly similar to the measured ones. 相似文献
12.
The assessment of social vulnerability is a requirement for understanding the risk of natural hazards. This paper calculates the social vulnerability index of geological disasters in China with the super-efficiency DEA (data envelopment analysis) model, carries out global and local autocorrelation tests for social vulnerability to geological disasters in each province in China and identifies the characteristics of its spatial distribution pattern. The results show the following. (1) China’s social vulnerability to geological disasters is relatively high and has obvious differences. It represents the pattern of a significant increase by degrees in social vulnerability to geological disasters from east to west and a significantly negative correlation relationship between the vulnerability level and the economic level. (2) Based on the comparative analysis of the mean values of the indexes and the social vulnerability index of geological disasters, it is found that the social vulnerability index of geological disasters in China is directly related to the regional exposure degree and reaction and recovery ability, among which the reaction and recovery ability has great effects on the social vulnerability index. (3) Most of the regions in China are in a high–high clustering area or a low–low clustering area; that is to say, the regions with similar social vulnerability to geological disasters represent the pattern of clustering. 相似文献
13.
This paper describes 11 microfacies types in late Bathonian–Early Callovian carbonates of the Kuldhar Member of the Jaisalmer Formation (Rajasthan) and the Keera Golden Oolite Member of the Chari Formation (Kachchh Mainland) western India. The different microfacies associations reported in this study reflect an ideal shallowing upward sequence, representing a system of bioclastic bars developed on the lower ramp, evolving into an oolitic bar-to-bank system separating restricted lagoonal—from lower ramp environment. Four main types of cements, i.e. bladed, fibrous, syntaxial overgrowth and blocky cement (characterized in a few cases by ferroan calcite and anhydrite II) occur in these carbonates. The study also reveals that chemical compaction followed the two phases of early mechanical compaction that largely governed porosity of these limestones. However, micritization and neomorphism also contributed significantly in this respect. Diagenetic signatures in these carbonates suggest that marine phreatic and fresh water phreatic environments dominated, but deep burial diagenesis also played its role in shaping these rocks. The early and late diagenetic changes have been controlled by the depositional facies evolving in a basin riddled with rifting in an extensional tectonic regime forcing regional-scale sea level fluctuations. 相似文献
14.
K. N. S. S. S. Srinivas M. Srihari Rao P. Pavan Kishore D. Gopinadh Haris Raza Kusumita Arora H. V. S. Satyanarayana 《Journal of the Geological Society of India》2018,91(5):569-574
Boreholes are the only sources for direct measurements of geological and geophysical characteristics of the shallow subsurface of the earth. Borehole imaging tool “Acoustic Televiewer (ATV)” is an advanced probe, which records 3D image of the bore hole wall and is used to obtain oriented images of bore hole and provides substantial information regarding lithology, structural information, detection of fractures and casing of the borehole. The images are highly sensitive to the presence of fractures, the delineation of which becomes accurate and reliable based on these acoustic images. Features identified on log-derived images can be correlated with core samples or can be used as substitute in the poor core recovery zones. In the present study, ATV log from a deep borehole drilled at Khadi Kolavan in Koyna-Warna region of Ratnagiri district, Maharashtra located west of the Western Ghat escarpment in the Deccan Volcanic province, India, is used for interpretation of structural characteristics of the formation. The same was correlated with other conventional logging methods such as resistivity and full waveform sonic (FWS) as well as core logging and rock quality designations (RQD) which generated new understanding of the basement and basalt cover in this region. 相似文献
15.
Arina Khan Haris Hasan Khan Rashid Umar Muneeb Hasan Khan 《Hydrogeology Journal》2014,22(7):1561-1572
A modified DRASTIC model in a geographic information system (GIS) environment coupled with an information-analytic technique called ‘rough sets’ is used to understand the aquifer vulnerability characteristics of a segment of the lower Kali watershed in western Uttar Pradesh, India. Since the region is a flat plain, topography (T) is removed as a potential control. Other parameters are the same as in DRASTIC, hence the new model is termed as DRASIC. The rough set technique is employed to provide insight into the relative vulnerabilities of different administrative units (blocks) within the study area. Using rough sets, three important factors are computed: strength, certainty and coverage. Strength indicates how the vulnerability characteristics vary in the entire area, certainty gives the relative fractions of low, medium and high vulnerability regions within a particular block, and coverage computes the percentage of a particular vulnerability state in each block. The purpose of the work is to demonstrate the utility of this integrated approach in classifying different administrative blocks in the study area according to their aquifer vulnerability characteristics. This approach is particularly useful for block-level planning and decision making for sustainable management of groundwater resources. 相似文献