1991 Racha earthquake

1991 Racha earthquake
1991 Racha earthquake is located in Georgia
1991 Racha earthquake
UTC time1991-04-29 09:12:48
Local date29 April 1991 (1991-04-29)
Local time13:13
Magnitude7.0 Mw
Depth17 km[1]
Epicenter42°27′11″N 43°40′23″E / 42°27′11″N 43°40′23″E / 42.453; 43.673
Areas affectedGeorgia
Max. intensityIX (Destructive)
Casualties270 killed

The 1991 Racha earthquake occurred in the province of Racha, Georgia, at 9:12 UTC on 29 April. Centered on the districts of Oni and Ambrolauri on the southern foothills of the Greater Caucasus mountains, it killed 270, left approximately 100,000 homeless and caused severe damage, including to several medieval monuments.[2] It had a magnitude of 7.0 and was the most powerful earthquake recorded in the Caucasus.[3]

Tectonic setting

Georgia lies between the two mountain chains of the Greater Caucasus in the north and the Lesser Caucasus in the south. These two sets of mountains have both resulted from the continuing effects of the collision between the Arabian Plate and the Eurasian Plate. The Greater Caucasus consists of a southward-directed fold and thrust belt that has been active since the Oligocene. Racha lies close to the southern margin of this thrust belt and the earthquake is interpreted to be caused by rupture of the active thrust front.[4]