Quaternary tectonic evolution of the Northern Gulf of Elat/Aqaba along the Dead Sea Transform

Abstract

The northern Gulf of Elat/Aqaba is located in the transition between the deep marine basins of the gulf and the shallow onland basins of the Arava Valley. Interpretation of 500 km of high-resolution seismic reflection data collected across the northern shelf reveals the tectonic structure and evolution of this transition. Six NNE-trending faults and one E-W trending transverse fault are mapped. Slip rates are calculated based on measured offsets and age determination based on a radiocarbon-calibrated sedimentation rate and a Quaternary age model. The most active fault is the Evrona Fault that absorbs most of the left lateral slip within the basin with an average sinistral slip rate of 0.7 ± 0.3 mm/yr through the Late Pleistocene and 2.3-3.4 mm/yr during the Holocene. Two intrabasin faults east of the Evrona Fault that have been inactive for the last several tens of thousands of years were mapped, and motion from these faults has likely transferred to the Evrona Fault. The basin is flanked on the west by the Elat Fault and on the east by the Aqaba Fault. Both faults are marked by large bathymetric escarpments. Based on displaced seismic reflectors, we calculate a Holocene vertical slip rate of 1.0 ± 0.2 and 0.4 ± 0.1 mm/yr for the Elat and Aqaba Faults, respectively. The geometry, slip rates, and slip history of the northern Gulf of Elat/Aqaba faults show that during the Late Pleistocene several intrabasin faults became dominant across the basin but that during the Holocene the Evrona Fault accommodates most of the strike slip.

Seismic Hazards Implications of Uplifted Pleistocene Coral Terraces in the Gulf of Aqaba

“…Major strike-slip faults occur along both sides of this deep, although the eastern fault also displays a very large dip-slip component 1, 5, 48 . Taking a maximum terrace elevation of ~26 m, minus the higher MIS5e sea-level of 7 m, this yields a tectonic uplift of 19 m and an average uplift rate of 0.015 cm/yr for the past 125 kyr.

Figure 8Topographic and bathymetric profile across the deepest part of the Gulf of Aqaba (Aragonese Deep) in the general vicinity of the 22 November 1995 M S 7.2 earthquake 14, 15 and our coral terrace station 12 (Figs 2 and 3 and Table 1).

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Seismic structure beneath the Gulf of Aqaba and adjacent areas based on the tomographic inversion of regional earthquake data

“…Most scholars associate the origin of deep linear depressions along the DST, such as the Gulf of Aqaba and the Dead Sea, with the pullapart mechanism (Mann et al, 1983;Makovsky et al, 2008;Petrunin and Sobolev, 2008;Hartman et al, 2014). In this context, lateral displacements along a non-straight fault line should lead to the origin of compression and extension zones at the vicinity of the fault, and many studies have used both numerical modeling (Petrunin and Sobolev, 2008;Petrunin et al, 2012) and geological evidence (Ehrhardt et al, 2005) to demonstrate the possibility of such a scenario.…”

“…While there have been several local-scale offshore experiments in the northern Red Sea and in the Gulf of Aqaba (Ben-Avraham et al, 1979;Ginzburg et al, 1981;Ben-Avraham, 1985;Makovsky et al, 2008;Hartman et al, 2014), these studies mostly investigated the shallow structures beneath the sea floor that do not intersect with the resolved area of our study. The distributions of velocity anomalies shown in Fig.…”

“…Between the 1960s and 1980s, some reflection and refraction seismic studies used active sources to explore the detailed upper crustal structure beneath the Gulf of Aqaba (Ben-Avraham et al, 1979;Ginzburg et al, 1981;BenAvraham, 1985;Makovsky et al, 2008;Hartman et al, 2014). Seismic refraction data revealed a gradual southward decrease of the Moho depth from ∼ 35 km at the northern edge of the Gulf of Aqaba to ∼ 27 km in the southern part.…”

responses to reviewer 2

“…Tectonic activity in the Gulf of Aqaba region is responsible for high levels of seismicity, which represent a significant hazard for the local population. For example, in 1993 and 1995, two strong earthquake sequences with magnitudes reaching Mb = 5.8 and Mb = 6.7 (main shocks), respectively, occurred beneath the Aqaba basin (Abdel Fattah et al, 1997;Hofstetter, 2003). Understanding deep tectonic mechanisms is important for better assessment of the seismic hazard in this region.…”