Seismicity of the Northwestern Region of Libya: An Example of Continental Seismicity

Abstract

Libya is situated on the Mediterranean foreland of the African Shield; its seismicity and tectonics reflect the geological history of the north African craton. Libya is not considered a highly active seismic region (Gutenberg and Richter 1965). However, several earthquakes of magnitude > 6.0 have occurred in Libya during the past century. A number of authors have investigated the seismicity and seismotectonics of Libya (Seiberg 1932; Minami 1963; Gordan and Engdahl 1963; Campbell 1968; Goodchild 1968; Kebeasy 1980; Westway 1990; Suleiman and Doser 1994; Al-Heety and Eshwehdi 2004). These investigations show that seismic activity in Libya is documented back to A.D. 262 and A.D. 365, when two large events destroyed the ancient city of Cyrene. Most of the seismic activity is concentrated on the coast of the northwestern part of Libya in the Al Jabal Al Akhdar region. The seismicity of this coastal region extends to the north as far as Greece. Another active seismic zone is concentrated along the eastern margin of the NW-SE trending Hun Graben. The region offshore of Tripoli is active as well. The southern part of Libya appears to be largely aseismic. In previous investigations of seismicity in Libya, all data were collected from international sources such as the National Earthquake Information Center (NEIC), the International Seismological Centre (ISC), the European-Mediterranean Seismological Centre (EMSC), and the bulletins of the national networks ( e.g. , those in southern Europe, Egypt, Tunisia, and others). Until very recently, there has been no national seismic network; the Libyan Seismological Network began operation in early 2006. This study represents the first attempt to study the seismicity of Libya using records of a local seismic station, Gharyan station. (Gharyan station data are available from the office of the Libyan Seismological Observatory and are available …