LG WAVE ATTENUATION GARHWAL HIMALAYA REGION

Abstract

The Lg 0 has been studied in the Garhwal Himalaya using the Two-Station Method. The five earthquakes used in this study have occurred in 2011 & 2012 in the regions of HinduKush and Sikkim. The epicentral distances fall in the range of 1000 km with the focal depths greater than 50 km and magnitudes greater than 5. The events were recorded at the Tehri Seismic Station Network. Almost 4 station pairs could be formed from 12 station network and this was used to study the attenuation effects. The frequency dependent attenuation relation in the form of power law ' Qig = Q0 f ' where 'Q.' comes to be around 135 and 'n' comes out as 0.84. The Lg wave part was studied individually in all the seismograms. The Lg waves were dominant in seismograms of epicentral distances greater than 1000 km. The Lg wave in time windows of 10 and 30 seconds was studied. The 10 sec window did not give us consistent results while the 30 sec window was good enough. This study has demonstrated that the Lg 0 values are in agreement with other attenuation studies done in Garhwal Himalaya using coda wave and S-wave part of the seismogram.