Abstract Database

RAYLEIGH WAVE PHASE VELOCITIES OBTAINED USING DATA FROM THE MALAYSIAN NATIONAL SEISMIC NETWORK

MEE10504
Atifah Mohd Alwi
Supervisor: Tatsuhiko HARA
Country: Malaysia
Abstractfulltext

This study is an attempt to measure phase velocities using broadband waveform data from the Malaysian National Seismic Network (MNSN). We applied two-station method in the measurements of phase velocities of the fundamental mode Rayleigh waves. We selected 10 distant large (M>=6.5) earthquakes that occurred in 2009 and 2010. We computed the phase velocities using a cross-correlation technique for fundamental mode Rayleigh waves which were edited based on a range of group velocities between 2.6 and 4.0 km/s with visual checks of the waveforms. We computed two theoretical phase velocities based on PREM (with and without ocean) in calculation of phase velocities. The phase velocity measurements are divided into three groups based on the difference of paths (i.e., the Malay Peninsula, the Borneo Island, and the South China Sea (ocean path)). We computed average phase velocities for these groups. For the Borneo Island, the standard deviation is relatively larger due to larger scattering of the measurements. For this reason, we only discuss the results for the ocean path and the Malay Peninsula. The average phase velocities obtained for the Malay Peninsula and the ocean path are not largely different from theoretical phase velocities calculated for PREM. In order to investigate effects of crust structures for the phase velocities, we constructed seven structure models referring to CRUST2.0, and computed phase velocities for them and model iasp91. These phase velocities relatively well explain the observed phase velocities at shorter period range (30-90 s). The differences between the observed and theoretically computed phase velocities at longer period range (100-140 s) may indicate the differences of mantle structures beneath these regions.