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Mandal Prantik Srinagesh D. Vijayaraghavan R. Suresh G. Naresh B. Raju P. Solomon Devi Aarti Swathi K. Singh Dhiraj K. Srinivas D. Saha Satish Shekar M. Sarma A. N. S. Murthy YVVBSN 《Natural Hazards》2022,111(3):2241-2260
Natural Hazards - Since the initial collision at 55 Ma, rocks of the Indian crust below the Himalayas have undergone modification chemically and compositionally due to the ongoing... 相似文献
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V. O. Mikhailov K. Arora A. V. Ponomarev D. Srinagesh V. B. Smirnov R. K. Chadha 《Izvestiya Physics of the Solid Earth》2017,53(4):518-529
The state of the art in the geological and geophysical study of the region of Koyna and Warna water reservoirs is reviewed. The probable geodynamical factors of induced seismicity are discussed. The detailed geophysical surveys, satellite geodetic data, and time history of the seismicity in the region reveal a complicated pattern of the structure and recent geodynamics of the region. The existing data suggest that the induced seismicity is here most likely to be caused by the regional (intraplate) stresses driving the displacements along the orthogonal network of the faults whose strength has dropped and continues decreasing due to the reservoir impoundment and operation processes. The evolution of the seismicity which started immediately after the rapid filling of the Koyna reservoir in the region of the dam, then rapidly expanded southwards and eventually became concentrated in the region of the subsequently constructed Warna reservoir shows that seismic events can be initiated by a number of factors whose contributions may vary with time. The key ones among them include reservoir loading and its seasonal variations; water saturation of the faults which guide the propagation of the front of fracture, increased permeability, and, probably, mineral transformations (hydrolysis) under the water level fluctuations in the reservoirs; and displacement of the front of the high pore pressure down to the main source zone of the earthquakes at a depth of 6–8 km. Based on the analysis presented in the paper, we outline the directions of the future research aimed at studying the nature and dynamics of induced seismicity in the region of large water reservoirs. 相似文献
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Vettegren V. I. Ponomarev A. V. Mamalimov R. I. Shcherbakov I. P. Arora K. Srinagesh D. Chadha R. K. 《Izvestiya Physics of the Solid Earth》2019,55(6):879-885
Izvestiya, Physics of the Solid Earth - Abstract—The growth rate and size of microcracks formed in the surface layer of basalt and tonalite (granodiorite) at friction are studied using... 相似文献
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K. Mallika Harsh Gupta D. Shashidhar N. Purnachandra Rao Amrita Yadav Sunil Rohilla H. V. S. Satyanarayana D. Srinagesh 《Journal of Seismology》2013,17(1):189-195
It is generally found that the b values associated with reservoir-triggered seismicity (RTS) are higher than the regional b values in the frequency magnitude relation of earthquakes. In the present study, temporal and spatial variation of b value is investigated using a catalog of 3,000 earthquakes from August 2005 through December 2010 for the Koyna?CWarna region in Western India, which is a classical site of RTS globally. It is an isolated (30?×?20?km2) zone of seismicity where earthquakes of up to M ??5 are found to occur during phases of loading and unloading of the Koyna and Warna reservoirs situated 25?km apart. For the Warna region, it is found that low b values of 0.6?C0.9 are associated with earthquakes of M ??4 during the loading phase. The percentage correlation of the occurrence of an M????4 earthquake with a low b value outside the 1?? or 2?? level is as high as 78?%. A drastic drop in the b value of about 50?% being reported for an RTS site may be an important precursory parameter for short-term earthquake forecast in the future. 相似文献
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Mandal Prantik Srinivas D. Vengala Pavan K. Srinagesh D. Suresh G. Naresh B. 《Natural Hazards》2022,114(1):205-235
Natural Hazards - Here, we present crustal and lithospheric structure at six broadband stations below the Palghar swarm activity region, Maharashtra, India, which has produced 7786 events of... 相似文献
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S. S. Rai D. Srinagesh P. V. S. S. Rajagopala Sarma 《Journal of Earth System Science》1996,105(4):441-450
Earthquake hypocenters and travel time residuals have been analysed to constrain the geometry and physical state of the subducted
Indian plate in the Indo-Burmese convergence zone. A critical analysis of earthquake hypocenters reveals the existence of
a non-uniform Benioff zone, progressively shortening from north to south. The deepest level of seismicity is observed beneath
the Naga hills (160 km) followed by that under the Chin hills (120 km) and Arakan-Yoma ranges (80 km). The region seems to
be devoid of moderate sized shallow (< 40 km) earthquakes. Differential travel time residuals from pairs of shallow and intermediate
depth earthquakes recorded at teleseismic distances show significantly faster travel time (up to l.2s) in the north-northeast
and south-southwest azimuths, whilst slower arrivals (1.2 to 1.5 s) are recorded in the transverse direction. This observation
points to the presence of a high velocity slab possibly linked to the subduction of the Indian oceanic lithosphere. 相似文献
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H M Iyer V K Gaur S S Rai D S Ramesh CVR Rao D Srinagesh K Suryaprakasam 《Journal of Earth System Science》1989,98(1):31-60
Analysis of teleseismicP-wave residuals observed at 15 seismograph stations operated in the Deccan volcanic province (DVP) in west central India points
to the existence of a large, deep anomalous region in the upper mantle where the velocity is a few per cent higher than in
the surrounding region. The seismic stations were operated in three deployments together with a reference station on precambrian
granite at Hyderabad and another common station at Poona. The first group of stations lay along a west-northwesterly profile
from Hyderabad through Poona to Bhatsa. The second group roughly formed an L-shaped profile from Poona to Hyderabad through
Dharwar and Hospet. The third group of stations lay along a northwesterly profile from Hyderabad to Dhule through Aurangabad
and Latur. Relative residuals computed with respect to Hyderabad at all the stations showed two basic features: a large almost
linear variation from approximately +1s for teleseisms from the north to—1s for those from the southeast at the western stations,
and persistance of the pattern with diminishing magnitudes towards the east. Preliminary ray-plotting and three-dimensional
inversion of theP-wave residual data delineate the presence of a 600 km long approximately N−S trending anomalous region of high velocity (1–4%
contrast) from a depth of about 100 km in the upper mantle encompassing almost the whole width of the DVP. Inversion ofP-wave relative residuals reveal the existence of two prominent features beneath the DVP. The first is a thick high velocity
zone (1–4% faster) extending from a depth of about 100 km directly beneath most of the DVP. The second feature is a prominent
low velocity region which coincides with the westernmost part of the DVP. A possible explanation for the observed coherent
high velocity anomaly is that it forms the root of the lithosphere which coherently translates with the continents during
plate motions, an architecture characteristic of precambrian shields. The low velocity zone appears to be related to the rift
systems (anomaly 28, 65 Ma) which provided the channel for the outpouring of Deccan basalts at the close of the Cretaceous
period. 相似文献
10.
In estimating the likelihood of an earthquake hazard for a seismically active region, information on the geometry of the potential
source is important in quantifying the seismic hazard. The damage from an earthquake varies spatially and is governed by the
fault geometry and lithology. As earthquake damage is amplified by guided seismic waves along fault zones, it is important
to delineate the disposition of the fault zones by precisely determined hypocentral parameters. We used the double difference
(DD) algorithm to relocate earthquakes in the Koyna-Warna seismic zone (KWSZ) region, with the P- and S-wave catalog data
from relative arrival time pairs constituting the input. A significant improvement in the hypocentral estimates was achieved,
with the epicentral errors <30 m and focal depth errors <75 m i.e. errors have been significantly reduced by an order of magnitude
from the parameters determined by HYPO71. The earthquake activity defines three different fault segments. The seismogenic volume is shallower in the south by 3 km,
with seismicity in the north extending to a depth of 11 km while in the south the deepest seismicity observed is at a depth
of 8 km. By resolving the structure of seismicity in greater detail, we address the salient issues related to the seismotectonics
of this region. 相似文献