EQ II is the penultimate paleoseismic event 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 II is the penultimate event (PE) identified in the Sisters’ School trench log. It is expressed in the upper middle part of the southwest trench wall, where three faults rupture upward to the contact between unit SS-7 and the overlying fluvial unit SS-5. The principal paleoseismic evidence consists of upward fault terminations, vertically offset stratigraphic units, and the abrupt truncation of the EQ II fault tips at the SS-7/SS-5 contact. Allison interpreted this as evidence that the uppermost fault terminations were partially removed when the higher-energy fluvial deposition of unit SS-5 scoured into the underlying sediments. Unlike EQ IV and EQ V, there is no emphasis on mismatched unit thicknesses across fault lines as key evidence for this event, nor were any sand dikes directly associated with EQ II. The event is therefore identified primarily from fault truncation and offset stratigraphy. Within the broader tectonic setting of the site, EQ II likely reflects continued deformation within the same mixed strike-slip and cross-fault system affecting the Sisters’ School trench.
A terminus post quem for EQ II is established by unit SS-7, the youngest stratigraphic unit cut by the event. OSL sample #1, collected from SS-7, yielded an OSL age of 7.6 ± 0.6 ka, equivalent to 6200-5000 BCE. Additional constraint comes from radiocarbon sample RC-SS #1 from underlying unit SS-10, which produced a laboratory age of 6015 ± 25 yr BP and a calibrated age range of 4986-4840 BCE (2σ). A terminus ante quem is established by overlying unit SS-5, which scoured and buried the EQ II fault terminations. OSL sample #3, collected from SS-5, yielded an age of 6.0 ± 0.3 ka, equivalent to 4300-3700 BCE. Taken together, these constraints indicate that EQ II most likely occurred between approximately 5000 and 3700 BCE.
- 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)
