THE FIRST VIEW ON STRESS DROP OF SMALL EARTHQUAKES IN THE KIVU REGION, WESTERN BRANCH OF EAST AFRICAN RIFTS SYSTEM

Résumé fourni par la source

Digital seismograms recorded at seismic station of Lwiro, between August 1993 and March 1994, are used to investigate the spatial distribution of stress drop estimated following the spectral Brune's model in the Kivu region and its vicinities. It is revealed that a small stress drop (<=1) is observed in these zones. The high stress drops are observed in the granitic intrusion in the zone A and D (Idjwi Island) and B, on fracture linked Nyiragongo and Nyamuragira volcanoes, and the lowest is very scattered in the zone C, D and E. The study has revealed that the stress drops correlate with fault types as the high value corresponds to reverse faults in the zone B, and the lowest to normal and strike slip faults in other zones. The Idjwi Island also presents a high stress drop where three types of faulting appear. Small stress drops are attributed to strong barriers of seismic rupture or no long rupture propagation along the pre

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