Note: In contrast to the scientific theory presented below, the two tremors preceded, rather than follow, the expected passage of Super Typhoon Lan (130 knots or 149.6 mph) across the east coast of Japan.

Hurricanes and typhoons may trigger major earthquakes, according to new study
Eric Mack | New Atlas
Dec 30, 2011
https://newatlas.com/hurricanes-typhoons-may-trigger-earthquakes/20959/

{snip]

Hurricanes and typhoons could contribute to other natural disasters that occur long after the rain and winds subside. A new study led by University of Miami (UM) scientist Shimon Wdowinski finds a link between earthquakes and tropical storms, and shows that they may have actually initiated some major temblors, including the recent 2010 quakes in Haiti and Taiwan.

M 5.0 - OFF EAST COAST OF HONSHU, JAPAN - 2017-10-21 15:50:52 UTC
CSEM / EMSC

https://www.emsc-csem.org/Earthquake/earthquake.php?id=625520

Magnitude mb 5.0
Region OFF EAST COAST OF HONSHU, JAPAN
Date time 2017-10-21 15:50:52.5 UTC
Location 36.01 N ; 142.44 E
Depth 2 km
Distances 251 km E of Tokyo, Japan / pop: 8,337,000 / local time: 00:50:52.5 2017-10-22
183 km E of Mito-shi, Japan / pop: 247,000 / local time: 00:50:52.5 2017-10-22
148 km E of Hasaki, Japan / pop: 39,300 / local time: 00:50:52.5 2017-10-22

M 4.9 - NEAR EAST COAST OF HONSHU, JAPAN - 2017-10-21 16:25:52 UTC
CSEM / EMSC
https://www.emsc-csem.org/Earthquake/earthquake.php?id=

Magnitude mb 4.9
Region NEAR EAST COAST OF HONSHU, JAPAN
Date time 2017-10-21 16:25:52.1 UTC
Location 37.39 N ; 141.80 E
Depth 40 km
Distances 127 km SE of Sendai-shi, Japan / pop: 1,038,000 / local time: 01:25:52.1 2017-10-22
72 km E of Namie, Japan / pop: 21,900 / local time: 01:25:52.1 2017-10-22