Early Results of Surface Tomography Using Automated Surface-Wave Phase-Velocity Measuring System (ASWMS) in Hawaii

Abstract

The Hawaiian Islands are a prominent place to conduct seismicity research. Geologically, occurring earthquakes in this region are unique since it is caused by the presence of a hot spot rather than the common fault activity. The research was conducted using a tomography method called Surface Wave Tomography. The goals of this study are to produce tomographic images of the Hawaiian Islands and to test the accuracy of the Automated Surface-Wave Phase-Velocity Measuring System (ASWMS). ASWMS employs a cross-correlation process to calculate the phase delay between stations, then Eikonal equation to invert the slowness vector to obtain apparent phase velocities, and lastly Helmholtz equation to correct the amplitude to obtain structural phase velocities. The teleseismic data used in this study were collected from stations located throughout the Hawaiian Islands between 2004 and 2009. This study discovered a low-velocity anomaly beneath the Hawaiian Islands with a value of 3.8 – 3.9 km/s, indicating the presence of a low-velocity body. The decrease in velocity with increasing depth suggests an increase in temperature associated with the path that magma takes from the Earth’s mantle to the Earth’s crust beneath the Hawaiian Islands.