indoâ€“us workshop on â€œintraplate seismicityâ€ - The CERI Blog

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egions. Next, the estimated source parameters are compared with those of other stable continental region earthquakes, which have occurred in India and other parts of the world. This comparison study reveals that stress drop and seismic moment estimates of the 2001 Bhuj mainshock are found to be higher in comparison to all other stable continental earthquakes in the world. Based on the high stress drop, an intensity XI close to the epicenter and severe damage up to 350 km away from epicenter, we infer that near source ground accelerations associated with the 2001 mainshock may have been strong. We also use the deviatoric moment tensor inversion modeling of broadband waveforms for estimating the focal mechanism solutions for 13 earthquakes, which have occurred in different seismically active zones of Gujarat viz, KSZ, Cambay faults, Narmada-‐Son lineament and Saurashtra. These focal mechanisms show two consistent features. One feature suggests that one of the nodal planes for most of events strikes in an east-‐west to northwest-‐southeast direction showing a reverse mechanism with a minor right-‐lateral strike-‐slip component. Another feature is that the orientation of P axes is on a nearly NNE– SSW direction with some scatter. We propose that the estimated compressive stress direction being in the direction of plate motion may cause a state of high compressive stress in the region. S2-‐P2 Stress Inversion using Focal Mechanisms of Local Earthquakes in the Koyna-‐Warna Region, Western India D. Shashidhar, N. Purnachandra Rao and Harsh Gupta National Geophysical Research Institute (CSIR), Hyderabad The Koyna-‐Warna region is a well known seismic zone in western India associated with the largest reservoir triggered earthquake of M 6.3 in 1967. Using comprehensive data set of focal mechanism solutions the stress field of the region is inferred using the inversion method of Michael (1984, 1987). The data set comprises focal mechanism solutions of 48 earthquakes of magnitude of the order of 4 and above that occurred during 1967 to December 2010, which includes 31 solutions from previous studies and 17 solutions derived from waveform inversion approach in the present study. In the recent times most of the seismic activity is confined to the Warna reservoir situated about 25 km SSE of the Koyna
Dam which has been monitored since 2005, using a network of 11 digital seismic stations. In general fault plane solutions indicate mostly normal type faulting while a few solutions indicate strike-‐slip faulting. It can be seen that the Warna region is subjected to an east-‐ west extension with sub horizontal tensile stress axis (σ3) and sub vertical compressive axis (σ1) whose azimuth is in agreement with the tectonic scenario of the Indian plate collision with the Eurasian plate in the NNE direction. Further, a seismo tectonic model had been proposed based on the comprehensive focal mechanism data set that reveals alternate cycles of strike-‐slip and normal faulting followed by a period of seismic quiescence in the study region. S2-‐P3 Seismic Site Condition Assessment Using Seismic Surveying Techniques N. Thulasiraman * (Email:geothulasi@gmail.com) and K.Rajendran 1 (Email:kusala@ceas.iisc.ernet.in) 1 Centre for Earth Sciences, Indian Institute of Science, Bangalore, India. The Rann of Kachchh, part of the Indian stable continental region (SCR), is a unique region in the world where two large earthquakes (1819 & 2001) have occurred within a short span of 200 years. Both of the events caused wide spread liquefaction and damages due to site amplification. The rupture of 1819 M7.5 event reached the ground and created a distinct scarp of ~ 90 km length and 3-‐5 m high, popularly known as the “Allah Bund”. The 2001 Mw 7.7 Bhuj event occurred on a blind fault and did not create any primary surface rupture. However, the secondary effects such as liquefaction and ground deformation were wide spread around the epicentral region and they are well documented. A noteworthy feature of both these earthquakes is the large distances up to which the liquefaction effects were observed. For example, the 1819 earthquake is reported to have produced liquefaction at Porbandar located about 250 km from its source. Similarly, the 2001 earthquake produced severe damage in the city of Ahmedabad, located about 200 km away from the source of the earthquake. Apart from other lessons learned from these earthquakes, the observation that multifold amplification of seismic energy even at far locations, based on the local site conditions has become an important consideration in seismic hazard assessment.
Page 1 and 2: INDO-US WORKSHOP ON “INTRAPLATE S
Page 3 and 4: IUSSTF solicits proposals for its a
Page 5 and 6: area which caused severe damages an
Page 7 and 8: The USGS and several agencies of In
Page 9 and 10: LIST OF PAPERS 16 Jan POSTER SESSIO
Page 11 and 12: Institute of Seismological Research
Page 13 and 14: S6.6 Tectonic History and Related S
Page 15 and 16: not been a significant earthquake i
Page 17 and 18: earthquake-‐triggered landslide
Page 19 and 20: anticlockwise rotatory plate motion
Page 21 and 22: would require lesser stress/strain
Page 23 and 24: seismogenesis of lower-‐crustal
Page 25 and 26: Fig. 2: Seismic activity near the W
Page 27 and 28: Heat flux and crustal temperatures
Page 29 and 30: Ray, L., Kumar, P.S., Reddy, G.K.,
Page 31 and 32: The main shock and most of the afte
Page 33 and 34: aftershock decay rates, on the othe
Page 35 and 36: The first decade of the 21 st centu
Page 37: S2-‐P1 Study of Source Paramete
Page 41 and 42: shocks and in 2011 over 300 shocks
Page 43 and 44: 1 .Department of Earth and Planetar
Page 45 and 46: Weston Observatory, Department of E
Page 47 and 48: S4: Paleoseismology and Archaeoseis
Page 49 and 50: Kanter, 1990). The recent 2001 Bhuj

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indoâ€“us workshop on â€œintraplate seismicityâ€ - The CERI Blog