Surah 7. Al-A'raf, Ayah 78

Lit., "they became, in their homes, prostrate on the ground". The term rajfah which occurs at the beginning of this sentence signifies any violent commotion or trembling, and is often, though not always, applied to an earthquake (rajfat al-ard). It is possible that the earthquake mentioned here was accompanied by the volcanic eruption which at some time overtook the historical dwelling-places of the Thamud tribe, and to which the extensive black lava-fields (harrah) of northern Hijaz, and particularly near Mada'in Salih see note [59] above, bear eloquent witness to this day.

The retribution was not long delayed. A terrible earthquake came and buried the people and destroyed their boasted civilisation. The calamity must have been fairly extensive in area and intense in the terror it inspired, for it is described (liv. 31) as a "single mighty blast" (saihatan wahidatan), the sort of terror-inspiring noise which accompanies all big earthquakes.