MAJOR EARTHQUAKES IN ANTIQUITY ALONG THE DEAD SEA TRANSFORM IN AQABA, JORDAN

The ancient ruins of the city of Aqaba are located at the head of the Gulf of Aqaba along the seismically active Dead Sea transform fault in southern Jordan. Detailed archaeological excavation and geologic mapping was conducted during the summer of 2003 along active NW-trending cross faults that cut through Byzantine to Early Islamic deposits at the archaeological site of Aila in Aqaba. These data in combination with stratigraphic data from six prior excavation seasons of the Roman Aqaba Project provide the first record of the timing and slip for seven earthquakes (EQI-EQVII) that have ruptured Aqaba, Jordan since the 2nd Century A.D. The oldest event (EQ VII) caused major structural collapse at the site during the early 2nd Century A.D. EQVI caused minor structural damage to walls and floors across the site that were repaired in antiquity and may have been a foreshock to the much more damaging EQV. We documented 28 cm of dip slip and 30 cm of lateral slip for EQV. Based on sealed coin loci, we have correlated EQV to the May 19, 363 A.D. earthquake that caused major destruction at sites across the region. After EQV the monumental use of the structure was converted to domestic use in the late 4th to early 5th Century. EQIV with 12 cm of dip slip is constrained to have ruptured through the site after the abandonment of the domestic structures during the early to mid 7th Century. Later in the mid 7th to late 8th Centuries, a large magnitude earthquake (EQIII), with 54 cm of slip, ruptured early Islamic occupation strata at the site. The two most recent earthquakes, with 42 and 35 cm of dip slip, occurred some time after the 8th Century and may correlate to the historical earthquakes of 1068 and 1212 A.D. No stratified materials were found at this site that could be used to further refine the timing of EQ I and II. Our data suggest significant periods of active seismicity (M 6-7) in the 4th, 7th-8th, and probably in the 11th-13th Centuries. These data clearly show that historical earthquake catalogues are incomplete with regard to some of the less damaging earthquakes that have affect southern Jordan but may have played a significant role in the cultural history of the region. The data also document a long period of quiescence since the last phase of intense earthquake activity along the southern Dead Sea transform and highlight the elevated potential earthquake hazard in the region.