Event XT4 was identified in Trench T4 at Tell Saidiyeh, a site situated along the Jordan Valley Fault. Unlike the purpose-excavated Trench T3, Trench T4 originated as a cut made during agricultural leveling works and trends northwest–southeast, oblique to the fault trace. The exposure was subsequently widened and cleaned by Ferry et al. (2011). The trench exposes a well-developed fault zone affecting both late Pleistocene and Holocene deposits. Because the trench is oriented approximately 45° to the fault, the deformation zone appears wider than in a perpendicular exposure and provides an unusually detailed record of repeated surface ruptures.
The evidence for Event XT4 consists of a fan-shaped network of three fault splays located immediately southeast of fault zone FZ2. According to Ferry et al. (2011:54), these splays affect units h, g, and f and collectively produce approximately 5 cm of cumulative vertical displacement. The ruptures are consistently capped by a thin silty clay layer, demonstrating that faulting occurred before deposition of the overlying sediment. Ferry et al. also note that Event XT4 may be represented by an additional fault splay located immediately northwest of FZ3 that disrupts the contact between units g and f, although the upward termination of this feature could not be determined with certainty. Together, these observations indicate a distinct surface-rupturing earthquake that postdates the deposition of units h, g, and f but predates the subsequent sealing unit.
The chronology of Event XT4 is based primarily on two radiocarbon samples, Tbc-23 and Tbc-24, recovered from bulk soil deposits that bracket the event. Sample Tbc-23 yielded an age of 5060–4770 BCE, whereas the stratigraphically higher sample Tbc-24 yielded an older age of 5470–5110 BCE. According to Ferry et al. (2011:54), this apparent age inversion may reflect contamination, because both samples contained very small amounts of carbon, only about 0.6 mg. The authors suggest that contamination would most likely produce rejuvenation of the dates, implying that the true ages may be somewhat older than measured.
Taking both the stratigraphic relationships and the dating uncertainties into account, Ferry et al. (2011:54) conclude that Event XT4 most likely occurred shortly before deposition of the thin silty clay unit that seals the rupture. They estimate an occurrence between approximately 5470 BCE and 5000 BCE, placing the earthquake in the middle Holocene.
- Fig. 3b Location Map of the
Tell Saidiyeh Site from Ferry et al. (2011)
Geomorphology of the Tell Saidiyeh site from a high-resolution total station topographic survey (contour spacing 0.5 m). South of the archaeological tell (located ~100 m to the north; see inset in Fig. 8b), the morphology displays a recent terrace strath (Qto) affected and left-laterally displaced by the fault. The southern edges (dashed lines) of streams serve as piercing points because they are less likely to be eroded than the northern ones in a left-lateral setting. Stream El flows westward along the southern edge of Qto and is displaced by 7 ± 0.5 m across the fault. Stream W2 is a beheaded remnant of El and displays 114 ± 5 m of offset. A minimum emplacement age of 22 ka for W2 yields an average slip rate of 4.9 mm/yr for that period. Solid rectangles represent trenches T3 and T4, which display faulting evidence for the last 17 ka. Blanked areas could not be surveyed because of the presence of agricultural and military facilities.
click on image to open in a new tab
Ferry et al. (2011)- Fig. 5E Stratigraphic Correlation
between Ghor Khabed and Tell Saidiyeh Trenches from Ferry et al. (2011)
Correlations of stratigraphic sections of trenches. The geological formations of Lisan and Damya are common basement-bottom units for trenches. Erosion processes (tilde lines) have major effects on soft sediments, and Trench T3 shows a significant hiatus of the Damya formation. The correlation between alluvial and lacustrine deposits and the related radiocarbon dating (see also Table 1 and Fig. 7) illustrate the different recent depositional environments at trench sites.
click on image to open in a new tab
Ferry et al. (2011)- Table 1 Radiocarbon Table
from Ferry et al. (2011)
Radiocarbon Dating of Samples Collected in Trenches T1 and T2 (Ghor Kabed Site) and T3 and T4 (Tell Saidiyeh Site)
click on image to open in a new tab
Ferry et al. (2011)- Fig. 4a Oblique view of trench
T4 showing Lisan units affected by faulting and liquefaction from Ferry et al. (2011)
Oblique view of trench T4 showing Lisan units affected by faulting and liquefaction in the foreground and sand and silt units in the background
click on image to open in a new tab
Ferry et al. (2011)- Fig. 4b Main Shear Zone of trench
T4 from Ferry et al. (2011)
The main shear zone [of Trench T4) is outlined by a 1-cm-thick layer of crushed sand (thick lines) and displays numerous oriented pebbles.
click on image to open in a new tab
Ferry et al. (2011)Fig. 5d
Trench T4 is originally a road cut that was noticeably extended and cleaned. It is oriented 45° to the fault, which widens the deformation zone. This exposure provides the bulk of the paleoseismic dataset. See text for details.
click on image to open in a new tab
Ferry et al (2011)
