Earthquakes near Izumo through history

The deadliest was not the strongest: a magnitude 7 on September 10, 1943 (18 km ENE of Kurayoshi, Japan), for which NOAA records 1,400 deaths. NOAA’s list of significant earthquakes has 9 here, back to 1026. NOAA records deaths in 4 of the events here, 3,209 in all. The latest on NOAA’s list is a magnitude 5.7 on April 8, 2018 (Shimane Prefecture). NOAA’s record here begins on June 16, 1026 with an earthquake (Off Masuda, Shimane Prefecture). It grows thinner going back: 5 of the 9 significant earthquakes NOAA lists here are from 1927 on. NOAA lists one tsunami that began within 100 km of Izumo, and 4 from elsewhere that reached it with deaths or a metre of water or more. The highest water NOAA records here was 10 m, on June 16, 1026. The deadliest here came on June 16, 1026 from a magnitude 7.5 earthquake (Off Masuda, Shimane Prefecture): NOAA’s runup records count 1,000 deaths within 100 km of Izumo.

• April 8, 2018Earthquake · M 5.7Shimane PrefectureUSGS · NOAA NCEI
• September 10, 1943Earthquake · M 7.018 km ENE of Kurayoshi, Japan · 1,400 deaths (NOAA)USGS · NOAA NCEI · Wikipedia
• January 11, 1900Earthquake · M 7.8Sea Of JapanNOAA NCEI
• June 16, 1026Earthquake · M 7.5 (est.)Off Masuda, Shimane Prefecture · 1,001 deaths (NOAA)NOAA NCEI · Wikipedia
• June 16, 1026Tsunami · 10 m hereOff Masuda, Shimane Prefecture · 1,000 deaths here (NOAA)NOAA NCEI · Wikipedia

• An event counts for Izumo when it began within 100 km of its centre, or 200 km for an earthquake of magnitude 7 or more. Damage can reach further.
• USGS counts here start at magnitude 6: the catalogue’s smaller quakes thin out going back, where few instruments listened.
• NOAA lists significant events only: earthquakes that killed, did about $1 million of damage, reached magnitude 7.5 or intensity X, or raised a tsunami, and eruptions and tsunamis by like measures. Magnitudes before 1900 are its estimates from written accounts.
• Deaths are NOAA’s total for each event, wherever people died, its tsunami and fires included. A tsunami counts the dead its runup records give for this place: NOAA’s total for a tsunami includes its source quake’s.
• A tsunami from elsewhere counts where one of its runups killed or rose a metre or more.
• Counted to October 19, 2026, as is the map. The last 30 days ask USGS again.

How the layers work, where their data comes from and what they can’t tell you: Earthquakes, live, The world through history