The 1905 Bolnai earthquake occurred in or near the Asgat Sum of Zavkhan Province in Mongolia on 23 July.

The fault displacement during the earthquake was greater than 6 m,[5] and possibly as much as 11 m,[2] and the duration is estimated at two minutes.

[2] There are few records of the immediate effects of the earthquake due to the remoteness of Mongolia in 1905.

However, rockslides were reported in the nearby mountains, and supposedly "two lakes, each of eight acres in size, disappeared".

[6] Lasting damage of the earthquake can be seen in the Mongolia special of the Amazon Prime motoring show The Grand Tour.