2961 Bulletin of the Seismological Society of America, Vol. 92, No. 8, pp. 2961–2982, December 2002 A Case Study in Archaeoseismology. The Collapses of the Selinunte Temples (Southwestern Sicily): Two Earthquakes Identified by Emanuela Guidoboni, Anna Muggia, Clemente Marconi,* and Enzo Boschi Abstract This article presents the results of research aimed at enhancing our knowledge of the active faults in southwestern Sicily, which is considered a low seismic hazard zone. The Selinunte archaeological park, the largest in the Mediter- ranean, with its great temples and evidence of spectacular collapses, is an information source that can be analyzed using the methodological approach of archaeoseismol- ogy. Having assessed the situation concerning the interpretation of the collapse in the literature (seismic and nonseismic events), we have proceeded to identify the seismic indicators at Selinunte, which has required a detailed analysis of both old and new archaeological evidence. We have reconstructed the history of the archae- ological deposits, spoliation, and excavations. These data have been reevaluated in the light of the most recent research and of methodological criteria already success- fully used in previous works on archaeoseismology. By means of a detailed and systematic critical analysis of the archaeological data, we have formulated a hypoth- esis arguing that two seismic events had actually struck Selinunte, leading to the collapse of the temples. One of the methods for this analysis is to visualize the direction of the temples’ collapse, pinpointing congruent chronological phases. The results have allowed us to date the two earthquakes to a period between the fourth and third centuries B.C. for the first, and for the second between the sixth and thir- teenth century A.D. This work has provided new information for the archaeological identification of seismic events in the total absence of written information. Introduction: The Seismic Riddle of Southwestern Sicily Southwestern Sicily is considered to be an area of in- frequent seismic activity. Only one earthquake of M 5.5 is known to have occurred in historic times in this part of the island. It struck the Belice valley on 13 January 1968 (I o  X Mercalli–Cancani–Sieberg [MCS], M 6.5) (see Boschi et al., 2000). No other reference to a strong earthquake in this region has been found in the earlier earthquake catalogs. Research in historical seismology carried out in recent years has not yet come up with any new information for the south- western part of the island (Guidoboni et al., 1994; Guidoboni and Traina, 1997) (particularly dealing with Sicily). The tectonic evolution of the region around Selinunte is controlled by south- and southeastern-verging thrusts and a north–south trending right-lateral strike-slip fault. Al- though some of these features are reported to be active by *Present address: Department of Arts History and Archaeology, Colum- bia University, New York, New York; cm583@columbia.edu. some investigators, very little evidence exists to date for the location, geometry, and kinematics of the main seismogenic sources of the region (Bigi et al., 1989; Amadori et al., 1992; Balia, 1992). The hypotheses on the seismogenic sources have been elaborated by Valensise and Pantosti (2001) and are portrayed here in Figure 1a. Noteworthy is the lack of historical seismicity in western Sicily and particularly around Selinunte. In regard to the geology of the area being examined, according to the Carta Geologica d’Italia (Servizio Geolo- gico d’Italia, 1971), most of the Selinunte archaeological area is built on Middle Pleistocene littoral deposits with sandy-clayey intercalations (Piro and Versino, 1995). The age of these deposits is constrained by the presence of typical cold-climate microfossils and macrofossils such as Cyprina Islandica (Fig. 1b) When this study was begun in 1998, it was clear that there was a need for a better understanding of this area’s seismicity. To this end, it was decided that the archaeological