Reviewed by USGSJapan region88y ago
M6.6 earthquake in Volcano Islands, Japan region
Wednesday, May 17, 1939, 18:30:38 UTC · 23.101°N, 143.418°E
A magnitude 6.6 earthquake struck in Volcano Islands, Japan region on Wednesday, May 17, 1939, 18:30:38 UTC, at a depth of 35.0 km (shallow). It is the strongest earthquake within 300 km since an M7.5 on February 24, 1934.
- Magnitude
- 6.6
- Strong · mw
- Depth
- 35 km
- Shallow
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- —
- No ShakeMap
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquake
In context
How big was it, and why here?
Energy released
138 kilotons of TNT
That is about 9 times the Hiroshima bomb. It released about 288 times the energy of a magnitude 5.0.
Tectonic setting
84 km
from the nearest mapped plate boundary, between the Philippine Sea and Mariana plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
35 km
Shallow earthquakes (under 70 km) produce the strongest surface shaking for their size, so they are the ones most likely to cause damage near the epicenter.
Did You Feel It?
Where it was felt
No “Did You Feel It?” reports have been published for this event yet. If you felt it, you can add your report on the USGS website.
I felt it — report to USGS ↗USGS PAGER estimate
Who was exposed to shaking
USGS publishes PAGER impact estimates for significant earthquakes, usually within an hour. No PAGER estimate is available for this event.
After the main event
Aftershocks within 100 km
USGS has not published any M2.5+ earthquake within 100 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 21 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.9Volcano Islands, Japan regionNovember 24, 1914 · 128 km SW of this epicenter
- 7.5Volcano Islands, Japan regionFebruary 24, 1934 · 60 km E of this epicenter
- 7.2Mariana Islands regionJuly 11, 1905 · 177 km S of this epicenter
- 7.1Volcano Islands, Japan regionMarch 23, 1913 · 140 km SW of this epicenter
- 6.6Volcano Islands, Japan regionMarch 11, 1931 · 30 km NE of this epicenter
- 6.4Volcano Islands, Japan regionJanuary 1, 1938 · 288 km N of this epicenter
- 6.2Volcano Islands, Japan regionMarch 9, 1929 · 198 km N of this epicenter
- 6.2Volcano Islands, Japan regionMarch 12, 1931 · 19 km SW of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 1 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1914M8.1
Volcano Islands
24 Nov 1914 · 130 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.