September 5, 1971 Earthquake: Sakhalin, Moneron Island, Russia

The southwestern part of Sakhalin experienced a severe earthquake. The maximum intensity of shocks and tremors (7-8 points on MSK-64) were observed on small Moneron Island where rock falls and landslides occurred on steep slopes on the western and eastern coasts. The largest rock falls were at the level of 10,000 m3 with individual blocks of 30-50 m3 which occurred on the northwestern coast. Smaller rock falls and landslides occurred on the southern part of the island. Deep inland there was no evidence of any rock falls, landslides or surface cracks.

In Sakhalin proper, the mining villages of Shebunino and Gomozavodsk were the most severely affected. In Shebunino, up to 75% of the chimneys and ovens in barrack-type buildings were damaged; isolated cracks appeared in the plaster and ovens of newly-built two-story houses of beam construction. In the mine, concrete supports and bulkheads were damaged; the methane level in the air exeeded the permissible level and work had to be stopped for 1.5 days. In Gornozavodsk, up to 35% of the structures were damaged. These were primarily frame-plastered houses on the marshy lower river terrace. Building damage was also reported in Nevel'sk, Kholmsk, Sinegorsk, and other places. Primarily small blocks and shabby frame-plaster structures were damaged. New panel and large-block buildings withstood the shocks well.

(above from reference #417)

1971, September 5, 18:35:25 UTC. 46.5 N, 141.2 E, depth 9 km, magnitude 6.3 mb, 7.1 MS. Felt (VII) on Moneron Island, (VI) in southern Sakhalin, and (III) JMA in northern Hokkaido. 1 meter tsunami reported at Moneron Island. (reference #1053)

1971, September 5, 18:35:29.57 UTC. 46.529 N, 141.185 E, depth 18.1 km, magnitude 7.3 Mw (reference #10476, v. 12.1)