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Saikia, Utpal
- Accurate Location and Focal Mechanism of Small Earthquakes near Idukki Reservoir, Kerala: Implication for Earthquake Genesis
Abstract Views :214 |
PDF Views:83
Authors
Utpal Saikia
1,
S. S. Rai
1,
M. Subrahmanyam
2,
Satyajit Dutta
1,
Somasish Bose
1,
Kajaljyoti Borah
1,
Rishikesh Meena
1
Affiliations
1 CSIR-National Geophysical Research Institute, Hyderabad 500 007, IN
2 Department of Geophysics, Andhra University, Visakhapatnam 530 003, IN
1 CSIR-National Geophysical Research Institute, Hyderabad 500 007, IN
2 Department of Geophysics, Andhra University, Visakhapatnam 530 003, IN
Source
Current Science, Vol 107, No 11 (2014), Pagination: 1885-1891Abstract
Earthquake waveform from a new temporary network of 21 seismic stations in South India has been used to significantly improve the detection threshold and parameters of small earthquakes near Idukki Reservoir, Kerala. We present here precise location of 16 earthquakes in this region with a local magnitude of 1.5-3.6 and focal depth 7.2-9.9 km. Fault plane solutions of the selected best six earthquakes show strikeslip faulting and right lateral movement. Reservoir loading usually leads to generation of stress and therefore earthquakes in the shallow depth (< 5 km), that are absent in the region of Idukki Reservoir. Recorded earthquakes are confined to a NW-SE trending fault close to Karur-Kamabam-Painavu-Trichur (KKPT) shear zone. These observations suggest that the earthquakes in Idukki region are tectonic in nature and have no linkage with the reservoir.Keywords
Earthquake Location, Fault Plane Solution, Reservoir, Tectonics.Full Text
- Estimation of Strong Ground Motion in Southern Peninsular India by Empirical Green's Function Method
Abstract Views :251 |
PDF Views:90
Authors
Affiliations
1 CSIR-National Geophysical Research Institute, Hyderabad 500 007, IN
2 School of Engineering, Indian Institute of Technology-Mandi, Kamand 175 005, IN
3 Department of Civil Engineering, Indian Institute of Technology-Madras, Chennai 600 036, IN
1 CSIR-National Geophysical Research Institute, Hyderabad 500 007, IN
2 School of Engineering, Indian Institute of Technology-Mandi, Kamand 175 005, IN
3 Department of Civil Engineering, Indian Institute of Technology-Madras, Chennai 600 036, IN
Source
Current Science, Vol 112, No 11 (2017), Pagination: 2273-2283Abstract
In the present study, strong motions are estimated at 17 stations in Southern Peninsular India (SPI) for the 7 February 1900 Coimbatore earthquake (Mw 6) using the empirical Green's function (EGF) method. The broadband recordings of three small earthquakes of ML 3.5, 2.9 and 3.0 respectively, are taken as EGFs to simulate ground motion. The slip distribution of the main event is considered as a von Karman random field. The stress drops of the three small events estimated from finite fault stochastic seismological model lie between 130 and 140 bars. The peak ground acceleration (PGA) values, an ensemble of acceleration time histories and response spectra, are estimated at all the 17 stations using corresponding EGFs, and the mean response spectra are reported. Another estimate of PGA is also obtained using the stochastic seismological model. The estimated PGA values from the two methods are compared to check the consistency of the results. It is observed that the mean PGA values are within the bounds of the maximum and minimum PGA values obtained from the EGF method, while the differences at some stations can be attributed to the local site conditions.
The ground motions simulated in the present study can be used to perform nonlinear dynamic analysis for future and existing structures in the SPI region for any event of magnitude Mw 6.
Keywords
Empirical Green’s Function, Ground Motion, Peak Ground Acceleration, Response Spectra, Stochastic Finite Fault Model.Full Text
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