Effects of large historical earthquakes on archeological structures in Jordan

This study tackles a set of conclusions and involves an evaluation of presumptive historical earthquakes in the Eastern Mediterranean Region, which hit the region and strongly affected the archeological sites in Jordan. Actually, the core of the study was the ancient cities of Umm Qais (Gadara), Umm Al-Jimal, Deir Al-Kahf, Al-Azraq, and Pella in the North and Dhahil water reservoir and Humaima in the South. The archeological excavations made during the past 20 years helped a lot of the region’s seismicity re-evaluation and relocation of historical earthquakes, about which the researchers argued on determining their epicenters and magnitudes. The recent excavations at Umm Qais (Gadara) indicated that earthquake-impacted ruins have been buried under nearly 2 m of dust deposits for centuries. So, such important indicators that can be relied upon to determine the epicenter and magnitude evaluation of these historical earthquakes were unveiled. Based on the recent available excavations, it is obvious that Umm Qais was affected by two seismic events within a time interval of not less than 100 years. In the light of the results found in Umm Qais and the remote archeological sites of Umm Al-Jimal and Deir Al-Kahf, there was no azimuthal projection of neither collapsed nor tilted columns indicating that there was a major earthquake with the epicenter located in the Carmel rupture zone in the North of Palestine, and not in the rift zone as reported earlier. But, the second earthquake was at the northwest of Umm Qais. The earthquake reported here seems to coincide with the reported major earthquake in 748 AD while the second one that occurred earlier corresponds to the 551 AD. The eastward collapsed towers in the South with respect to the southern archeological site of Humaima and a seismic swarm in Sep. 20, 2003, suggested that the Wadi Araba fault may not be continuous but segmented, subject to confirmation by detailed sub-surface structural information.