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Free keywords:
Africa; Body waves; Earthquake hazards
Abstract:
Well-constrained earthquake depth estimations are important for seismic hazard determination.
As local networks of the East-African Rift are usually too sparse for reliable depth estimations,
we used detections of pP and sP phase arrivals (the so-called depth phases) at teleseismic
distance to constrain earthquake depths in this region. We rely on a fully automatic Cepstral
analysis approach, first validated at the global scale using the ISC-EHB catalogue, then applied
on the East-African seismicity. We investigated 9575 earthquakes from magnitude 2 since
2005 which allows us to constrain the depth estimation of 584 events with magnitude mainly
above 3.5, complemented by 139 reliable depth estimations from previous studies based on
teleseismic data as well. To ensure a final catalogue as complete as possible, we also identified
from regional catalogues 113 earthquakes assumed to be well constrained, based on network
geometry empirical criteria. Thanks to this study, we finally propose new earthquake depth
distributions for the seismic source zonation defined by Poggi et al., in order to estimate the
seismic hazard of the East African Rift region. Including those new distributions in the source
models leads to significant changes of seismic hazard assessments results.
