A POSSIBLE NORMAL-FAULT RUPTURE FOR THE 464-BC SPARTA EARTHQUAKE

SURFACE ruptures have been identified for some normal-faulting earthquakes in the Aegean region 1-3, but for most historical earthquakes the associated faults are unknown. This hampers the evaluation of the rates and styles of present-day deformation, and the assessment of seismic hazard in the region 4. Here we examine the famous earthquake that destroyed Sparta in 464 BC. Using SPOT satellite images and fieldwork, we have mapped a 20-km-long normal fault scarp trending approximately north-south, a few kilometres east of the ancient city. Our observations, combined with an examination of historical descriptions of the earthquake damage, suggest that the Sparta earthquake ruptured this fault scarp in an event of magnitude M(s) almost-equal-to 7.2. The Holocene slip rate and the recurrence time for such large events on the Sparta fault would be approximately 1 mm yr-1 and approximately 3,000 yr, respectively.