Extensive archaeoseismic evidence was identified at Deir ʿAlla in Phase M (also referred to as Phase IX), particularly in Area B. The damaged mudbrick walls of the structures were built on top of existing surfaces, and occasionally on reed layers or wooden beams (Franken 1976). These walls lacked true foundations and were typically only one brick thick (Ibrahim and van der Kooij 1986: 135–142), making them structurally weak and highly vulnerable to seismic activity. Some of the deformation closely resembles what is seen in paleoseismic trenches, including vertical, mostly east–west-oriented cracks extending upward through the top of the stratigraphic layer (M/IX) and terminating at the base of subsequent deposits. One such crack, described as extensional, was approximately 10 cm wide (Franken 1976). Additional observations include mudbrick walls that sheared off at floor level, and others that broke higher up but after the whole wall had shifted (Franken 1976). Complete pottery, though often broken by the destruction of the buildings, was found in almost all of the rooms of Area B (Ibrahim and van der Kooij 1986: 138).

The stratigraphically confined cracks are attributed to the second of two earthquakes recorded at the site during the 8th century BCE (Franken 1976). The first earthquake caused a fire and apparent abandonment (Ibrahim and van der Kooij 1991), while the second occurred after some time, because the new surface had been used a bit (Ibrahim and van der Kooij 1991).

Franken and Ibrahim (1978: 60–68) suggested that it was raining when the second earthquake struck. Chronological indicators—including radiocarbon dates, non-wheel-thrown pottery , the palaeography of an inscription discovered in the rubble from the second quake, and the absence of Assyrian cultural influence —collectively point to an 8th or 9th century BCE date.