Fault-Plane Solutions of the 18 May 2001 earthquake in South Africa near Botswana border

Abstract

Fault-plane solutions of an earthquake can provide information about the type of fault. We report on the calculation of the fault-plane solutions of the earthquake that occurred on the morning of 18 May 2001 and was felt in the southern parts of Botswana and the North West Province of South Africa. The fact that there were few seismic stations in the vicinity of these areas meant that standard programs such as FOCMEC would produce a large number of possible fault-plane solutions. In this study a semi-manual method of determining fault-plane solution was utilized to obtain the most likely solution from a SEISAN program. The results obtained from these two methods shows that the focal mechanism for this earthquake was normal faulting. The two methods used compliment each other. Other information obtained includes epicenter at coordinates (longitude 26.0E, latitude 25.6S), magnitude of about 4.6 ML and origin time of 9:14.10.52 UTC.