Ambient Noise Cross-Correlation Study of Menengai Caldera: Geothermal Prospect in the Central Kenya Dome

Abstract

The Geothermal Development Company (GDC) and the University of Texas at El Paso (UTEP) have deployed fourteen seismic stations around the Menengai geothermal field along the Kenya rift system to monitor the seismicity around the host volcano to help identify active faults and fracture systems that may contain hydrothermal fluids and favorable drilling targets. Double difference relocation was used to locate events and to image faulting the margin of the caldera. We then apply an ambient noise tomography approach to image the Earth?s medium. Specifically, we cut the waveform data at single seismic station for every one hour in the vertical component and preprocess the noise using 1-bit normalization to eliminate the earthquake noise signal and the instrumentation irregularities. We apply spectral whitening to reduce the seismic amplitude. The cross-correlation between two different seismic stations were used to retrieve the Green?s function. We used Automatic Frequency time analysis (AFTAN) and phase match filtering analysis (MTA) in order to approximate the group velocities. Finally, we will then use the group velocity curves in a tomography algorithm to identify the hydrothermal reservoir zone.