Source parameters and scaling relations for small earthquakes in Sumatra Andaman Region
Abstract
The Andaman Nicobar Islands form the central part of the 5,000 Km long Burma- Sunda - Java subduction complex. The islands, situated to the southwest of the Indian subcontinent currently overlie one of most seismically active regions of the world. With the primary objective of understanding earthquake genesis and seismic hazard of the region a network of nine permanent stations has been established in the Andaman Nicobar Islands by CSIR- National Geophysical Research Institute, Hyderabad, India, under a project sponsored by the Ministry of Earth Sciences, Government of India (enclosed image). The purpose of present study is to estimate the earthquake source parameters and to investigate the self-similarity of small earthquakes (M 1 -4.5) in the Andaman Nicobar region of India. The spectral analysis P and S waves of seismograms of 75 earthquakes recorded at a broadband network in the region has been done for this purpose. For the proper evaluation of the seismic hazard potential in a region, determination of earthquake source parameters such as the seismic moment, stress drop, corner frequency, rupture dimension and scaling relations between them are basically important. The developed scaling relations provide the information whether the stress drop is constant or not for a given range of seismic moments.
In the present study we have estimated the source parameters for each event from P and S wave displacement amplitude spectra. The Seismic moments estimated from P waves, (P) range from 0.008 × 1020 Nm to 89.9 × 1020 Nm and those from S waves range from 0.00139 × 1020 to 13.9 × 1020 Nm and the stress drop is varying with the moment. One of the important conclusion of the present study is the breakdown of constant stress drop scaling for earthquakes with seismic moment. The increase in stress drop with increasing moment and noncorrelation of source radius with seismic moment shows that the stress drop is the dominant scaling factor for moments considered here. This work has important application in the evaluation of seismic hazard in the region as the stress drop controls the high frequency ground motion.- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.S51C0350G
- Keywords:
-
- 0902 Computational methods: seismic;
- EXPLORATION GEOPHYSICSDE: 0925 Magnetic and electrical methods;
- EXPLORATION GEOPHYSICSDE: 7255 Surface waves and free oscillations;
- SEISMOLOGYDE: 7290 Computational seismology;
- SEISMOLOGY