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Accurate Location and Focal Mechanism of Small Earthquakes near Idukki Reservoir, Kerala: Implication for Earthquake Genesis


Affiliations
1 CSIR-National Geophysical Research Institute, Hyderabad 500 007, India
2 Department of Geophysics, Andhra University, Visakhapatnam 530 003, India
 

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.
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  • Accurate Location and Focal Mechanism of Small Earthquakes near Idukki Reservoir, Kerala: Implication for Earthquake Genesis

Abstract Views: 362  |  PDF Views: 156

Authors

Utpal Saikia
CSIR-National Geophysical Research Institute, Hyderabad 500 007, India
S. S. Rai
CSIR-National Geophysical Research Institute, Hyderabad 500 007, India
M. Subrahmanyam
Department of Geophysics, Andhra University, Visakhapatnam 530 003, India
Satyajit Dutta
CSIR-National Geophysical Research Institute, Hyderabad 500 007, India
Somasish Bose
CSIR-National Geophysical Research Institute, Hyderabad 500 007, India
Kajaljyoti Borah
CSIR-National Geophysical Research Institute, Hyderabad 500 007, India
Rishikesh Meena
CSIR-National Geophysical Research Institute, Hyderabad 500 007, India

Abstract


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.



DOI: https://doi.org/10.18520/cs%2Fv107%2Fi11%2F1885-1891