Salvage excavations at Salat Tepe within the area to be flooded by the Ilisu-Dam gave evidence for a hitherto unrecorded earthquake on the Southeastern Anatolian Faultline between the plates of Anatolia and Arabia. The site is c. 5km to the north of Tigris and c. 75km to the south of the faultline (Figure 1.)
The construction of the building
The monumental Middle Bronze Age building excavated at Salat Tepe has already been reported (Ökse 2006). It stands at the summit of the 17m high Chalcolithic mound on a c. 3m high platform made of mud brick (Figure 2). The mudbrick walls, exposed to a height of 0.60m are erected on strong stone foundations constructed with huge limestone blocks. The mudbrick walls are 1.30cm thick and are built with mudbricks bonded to each other. No wooden beams and posts have been found of a type that would have supported the mudbrick walls. Layers of reeds were found between every 10 or 12 courses of mud brick, presumably to create a level surface for upper courses.
The crushed walls
The pebble surface of the open courtyard was covered by collapsed crushed mudbrick walls (Figure 3). The walls had fallen in three directions towards the large open courtyard, where no hindrance existed. The western section of Trench L 13 shows how the collapse had taken place (Figure 4): the thinner northern wall collapsed at first towards the south, and the thicker southern one later towards the north. The wall surrounding the courtyard from the west had fallen to the east. All walls had fallen through an angle of c. 90°, however, the upper mudbrick rows had fallen through an angle of c. 130°. The lower part of these walls remained standing to a height of c. 60-80cm on their stone foundations and the collapsed upper part of the walls resting on the pebble floor of the courtyard was c. 5m long. The original height of the walls must have been c. 5.5m high, suggesting a two-storeyed building. The mud bricks of the western and southern sections had broken apart and the walls in the south-western section of the building had broken over the steep slopes of the mound.
In many rooms there were traces of fire. One room in the central part of the building had the carbonised remains of a wooden weaving loom and two rooms in the south-eastern part were heavily burned. There were also heavily burned wooden door wings and wooden bolts of three doorways as well as the burned remains of a wooden construction in the north-eastern part of the courtyard.
The mound summit at Salat Tepe was immediately resettled after the destruction. The ceramic assemblages of the structures built directly on the collapsed walls are similar to those from the mudbrick fall; there are only a few Nuzi painted sherds in addition to the Middle Bronze Age ceramic assemblages consisting mainly of the Red-Brown Wash Ware (Parker & Dodd 2003), the Cooking-Pot Ware and the Khabur Painted Ware. These structures are dated to the sixteenth century BC, since the overlap between the Khabur and Nuzi wares is around sixteenth century BC (Oates et al. 2001: 68, 147; Akkermans & Schwartz 2003: 309). According to 14C analyses carried out on three fragments from the carbonised wood remains piled on the floor of a burned room, the building at Salat Tepe was in use in the seventeenth century BC.
The fall of the mudbrick walls was recorded in every trench on the mound summit at Salat Tepe, so it seems likely that all these walls had collapsed at the same time. There are a number of possible explanations, including deliberate demolition for rebuilding or to raise the ground level. But, in consultation with Prof. Dr. R. Ulusay from the Institute of Geology of the University of Hacettepe in Ankara, the most likely cause of such widespread and rapid collapse is an earthquake. Since the Middle Bronze Age buildings had no wooden posts and beams to support them and the building was two-storeyed, the walls standing on stone foundations were not able to resist the shock. The earthquake in question, taking place in about the sixteenth century BC should be attributed to the Southeastern Anatolian Faultline (The Bitlis Suture Zone).
However, no human skeletons were found under the crushed walls at Salat Tepe, and in situ remains are found only in some of the rooms, so there were few signs of an unexpected catastrophe, and the buildings were immediately rebuilt. If there was an earthquake, it should have affected a wider region, but there is not yet sufficient evidence that it did. Salvage excavations in the Upper Tigris Region have produced similar contemporary buildings on mound summits showing similar architectural features. As at Salat Tepe, all these buildings were built on the debris of earlier buildings dating to the Middle Bronze Age, such as the building at Kenantepe (Parker & Swartz Dodd 2005: 79). Building C in Giricano was built on a rubble layer within the preserved heights of the walls of Building A without any gap (Schachner 2002: 552-53; 2004: 509-10). Building A at Giricano is considered to have been abandoned systematically, since few small finds are attested within their contexts. There are also a number of instances of fires, such as the “Brightly Burned Building” at Ziyaret Tepe (Matney et al. 2004: 393), Level III at Kavusan Höyük (Kozbe & Köroglu, in print) and the MBA Level 11 at Üçtepe (Özfirat 2006: 19). On the floors of these buildings several vessels were crushed by the collapse. Nevertheless, no remains of such a collapse event is published in the preliminary reports of these excavations, so we cannot hypothesise a regional catastrophe.
In brief, while other explanations are possible, an earthquake is a plausible cause for the sudden and widespread collapse of the mudbrick walls at Salat Tepe. It seems likely that the effects were local and the inhabitants quickly overcame them. The latest earthquake on this faultline occurred on the 5th September 1975 (www.kronoloji.gen.tr). At Lice, a town located on the Southeastern Anatolian fault line, the earthquake (6.7) ruined 7000 mudbrick houses, closed a highway 144km long and killed c. 3000 people die. At Salat Tepe, the mudbrick houses of the modern village at Salat Tepe were just cracked during this event.