Focal Mechanism of a Recent Event in South Africa: A Study Using a Sparse Very Broadband Network

Abstract

INTRODUCTION In recent years, the rapid expansion of the Global Seismographic Network (GSN) has greatly enhanced our ability to monitor seismic events. Equipped with very broadband, three-component sensors, the GSN stations provide good coverage on most continents and contribute high quality data to basic scientific research and other monitoring purposes. At the same time, several GSN stations in a region of particular interest may be considered as a sparse regional network and become invaluable assets for earthquake source studies because source parameters of small to moderate-sized earthquakes provide important constraints on the local crustal structure, the stress field and the regional tectonics. Previously, the source parameters of small earthquakes (M ∼ 4.2 to 4.5) were successfully obtained from regional waveform data recorded at a single, very broadband seismic station (Fan and Wallace, 1991). Several research groups have reported near-real time source parameters retrieved from broadband waveforms in the western United...