EQ III was identified in the Sisters’ School trench in Aqaba, Jordan. The trench was an approximately 140 m by 100 m building foundation trench located about 1 km northeast of the head of the Gulf of Aqaba and about 1.3 km north of Early Islamic Ayla. The site exposed numerous fault strands within the urban Aqaba coastal zone, where the exact inland trace of the Aqaba fault remains difficult to identify because of modern development.
Allison (2013) interpreted the faults exposed at the Sisters’ School site as most likely related not to the Aqaba fault itself, but to the West-Aqaba fault, located west of the Aqaba fault strand. The trench also exposed evidence for northwest-trending cross faulting. Strike and dip measurements indicate that many faults trend close to north or northeast, broadly consistent with the West-Aqaba fault, while another group of faults trends northwest and may represent a transverse cross fault, possibly Cross Fault 6. The faulting therefore appears to record both strike-slip deformation and a normal-faulting component associated with local cross-fault motion.
EQ III is expressed in the middle part of the southwest trench wall, where faults rupture upward into the lower to middle portion of unit SS-10, the ashy anthropogenic layer, and are capped by overlying unit SS-7. The principal paleoseismic evidence consists of upward fault terminations within SS-10, vertically offset stratigraphic units, and associated paleoliquefaction features. Two small sand dikes or silt dikes, SD-2 and SD-3, are located in meter 4 and follow the EQ III fault line, providing direct evidence that seismic shaking was sufficient to induce liquefaction in water-saturated near-surface sediments during this event. Unlike EQ IV and EQ V, Allison did not emphasize mismatched unit thicknesses across fault lines as a defining characteristic of EQ III. The event is therefore best identified by fault terminations and associated liquefaction rather than by strong evidence for lateral strike-slip juxtaposition, although within the broader tectonic context of the site it likely reflects deformation within the same mixed strike-slip and cross-fault system.
A terminus post quem for EQ III is established by the youngest deformed unit, SS-10. OSL sample #4, collected from SS-10, yielded an OSL age of 6.6 ± 1.6 ka, equivalent to 6200-3000 BCE. Additional constraint comes from radiocarbon sample RC-SS #1, recovered from a fire pit in the same SS-10 stratigraphic horizon approximately 10 m east of the trench log, which produced a laboratory age of 6015 ± 25 yr BP and a calibrated age range of 4986-4840 BCE (2σ), which helps constrain the broad OSL range. A terminus ante quem is established by overlying unit SS-7. OSL sample #1, collected from SS-7, yielded an age of 7.6 ± 0.6 ka, equivalent to 6200-5000 BCE. Taken together, these constraints indicate that EQ III most likely occurred around 5000 BCE, probably within a relatively narrow interval between the deposition of SS-10 and the accumulation of the overlying SS-7 capping unit. Based on the ESI-2007 Intensity chart, the estimated local intensity for EQ III is approximately VIII (8), based on the presence of sand dikes observed in SD-2 and SD-3.
- Fig. 1.2 Location map from
Allison (2013)
Location map of research sites in southern Wadi ‘Arabah, Jordan
(Google Earth, 2013a)
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Allison (2013)- Fig. 4.1 Location map with
Geomorphology from Allison (2013)
Geologic map of the southern Wadi ‘Arabah. The Taba Sabkha trench location is shown at the top of the map (modified after Garfunkel, 1970). DST faults in Gulf of Aqaba from Hartman, 2012.
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Allison (2013)- Fig. 5.1 Location map with
faults from Allison (2013)
Location of Dead Sea transform faults mapped both offshore in the Gulf of Aqaba (white lines) and on land (dashed black lines). The solid back lines indicate transverse cross-faults mapped throughout the city of Aqaba, Jordan. Map from Tibor et al., 2010.
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Allison (2013)- Fig. 5.15 Fault Map around
trench site from Allison (2013)
Map of the city of Aqaba showing locations of the active cross faults (CF 1-5) mapped from aerial photos and discovered during the archaeological excavations of J-East in Roman-Byzantine Aila. The proposed location of cross fault 6 (CF-6) was determined as a result of this paleoseismic study at the Sisters’ School site. Locations of other major archaeological sites in the city are also shown (after Thomas et al., 2007).
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Allison (2013)- Fig. 5.2 Location map from
Allison (2013) (in Google Earth)
Location of Dead Sea transform faults mapped both offshore in the Gulf of Aqaba (white lines) and on land (dashed black lines). The solid back lines indicate transverse cross-faults mapped throughout the city of Aqaba, Jordan. Map from Tibor et al., 2010.
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Allison (2013)- Fig. 5.3 Detailed Location
map from Allison (2013)
Location map of Sisters’ School trench within the city of Aqaba, Jordan. The building foundation trench is outlined in black and the arrow points toward the southwest wall which contains the majority of faults identified at the site. Topographic contour lines, trending generally NW-SE, are shown with a 1 m contour interval.
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Allison (2013)- Fig. 5.4 Site plan from Allison (2013)
Top plan map of the Sisters’ School trench within the city of Aqaba, Jordan. The building foundation trench is outlined in black, and a red arrow points toward the southwest wall that contains approximately half of all the faults identified at the site. Faults and dikes identified in the trench walls are marked with either a short black line or a red strike and dip symbol where available and where space would allow. Fault lines in black are drawn perpendicular to their respective trench wall for uniformity and do not indicate direction of strike.
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Allison (2013)- Table 4.1 OSL and Radiocarbon Dating
Dating Results from Allison (2013)
Geochronology Of Sisters’ School Trench, Aqaba, Jordan
Optically Stimulated Luminescence (Osl) Dating Results And Radiocarbon Dating Results
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Allison (2013)Figure 5.8
Cross-section of both the north and south Taba Sabkha trench walls showing faulting, stratigraphic offset, and radiocarbon dates of charcoal samples collected.
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Allison (2013)
Figure 5.9
Paleoseismic faulting and a generalized stratigraphic section of the Sisters’ School southwest trench wall in Aqaba, Jordan. Colored stratigraphic units correlate to the colored cross-section of the SW trench wall (see Figure 5.8).
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Allison (2013)
