1905 Tsetserleg–Bulnay earthquakes

1905 Tsetserleg–Bulnay earthquakes
Tsetserleg
Bulnay
Ulaanbaatar
UTC time 
 1905-07-09 09:40:39
 1905-07-23 02:46:12
ISC event 
 16957859
 16957865
USGS-ANSS 
 ComCat
 ComCat
Local date 
 9 July 1905 (1905-07-09)
 23 July 1905 (1905-07-23)
Local time 
 17:40:39
 10:46:12
Magnitude 
 Ms7.9, Mw8.0
 Ms8.25, Mw8.3
Depth15.0 km
EpicenterNorthwestern Mongolia
Areas affectedMongolia
Max. intensityMMI VIII (Severe)

The 1905 Tsetserleg–Bulnay earthquakes occurred in remote northwestern Mongolia in July 1905. The magnitude 7.9–8.0 Tsetserleg shock struck on July 9 near the Tsetserleg Sum of Khövsgöl Province. The magnitude 8.25-8.4 Bulnay earthquake hit 2 weeks later on July 23 near Asgat Sum, Zavkhan Province on 23 July. The Tsetserleg earthquake ruptured 190 km (120 mi) of fault, while the Bulnay earthquake ruptured 455 km (283 mi). Geological effects from the earthquakes were widespread, and well documented. This earthquake sequence remains of scientific interest for two reasons: the sequence is the "largest continental strike-slip earthquake sequence ever documented", and the earthquakes started a cascade of triggered ruptures starting with each other, along with the 1931 Fuyun and 1957 Mongolia earthquakes.