Teleseismic investigation of the East African Rift - Kenya

Abstract

We recorded teleseismic events with 19 digital seismic recorders along a 600 km long profile across the East African rift in Kenya. At 5 stations three-component intermediate period seismometers were installed to investigate the presence of partial melt by comparing P- and S-delays. We find an average P-delay greater than 1.5 sec centered on the eastern flank of the rift. The delay pattern can be correlated with the upwarp of the asthenosphere/lithosphere boundary and resembles the Bouguer gravity along the profile. Structural models estimated from 2d-inversions (ACH-algorithm) of the observed delay times suggest a low-velocity zone is present down to large depths beneath the rift, dipping to the west. To the east of the rift LVZ's are located in the crust and upper mantle.