Reviewed by USGSJapan53y ago
M3.8 earthquake 25 km S of Nemuro, Japan
Saturday, July 28, 1973, 04:20:44 UTC · 43.097°N, 145.594°E
A magnitude 3.8 earthquake struck 25 km S of Nemuro, Japan on Saturday, July 28, 1973, 04:20:44 UTC, at a depth of 79.0 km (intermediate).
- Magnitude
- 3.8
- Minor · mb
- Depth
- 79 km
- Intermediate
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- —
- No ShakeMap
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeDashed circle: 50 km aftershock search area
In context
How big was it, and why here?
Energy released
8 tons of TNT
That is about 1/1,992 of the Hiroshima bomb. A magnitude 5.0 releases about 63 times more energy.
Tectonic setting
119 km
from the nearest mapped plate boundary, between the Okhotsk and Pacific plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.
Depth: intermediate
79 km
Intermediate-depth earthquakes usually break inside a plate that is sinking into the mantle. Shaking spreads over a wide area but is gentler at the epicenter than a shallow quake of the same size.
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 50 km
USGS lists 2 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M4.9 on August 4, 1973. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 441 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.31958 Kuril Islands EarthquakeNovember 6, 1958 · 278 km NE of this epicenter
- 8.21969 Hokkaido Toho-oki EarthquakeAugust 11, 1969 · 182 km E of this epicenter
- 8.11952 Tokachi-Oki EarthquakeMarch 4, 1952 · 179 km SW of this epicenter
- 7.970 km S of Honchō, JapanMay 16, 1968 · 287 km SW of this epicenter
- 7.7277 km SSE of Kushiro, JapanMay 3, 1919 · 272 km S of this epicenter
- 7.719 km ESE of Nemuro, JapanJune 17, 1973 · 22 km NE of this epicenter
- 7.542 km SSW of Shikotan, RussiaSeptember 11, 1935 · 91 km NE of this epicenter
- 7.426 km S of Shikotan, RussiaJanuary 29, 1968 · 103 km NE of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 36 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 107 recorded deaths. The most severe:
- 1843M8.4
Hokkaido: Yezo, Kushiro, Nemuro
25 Apr 1843 · 126 km away
45 deathsModerate damage ($1–5M)tsunami
- 1952M8.1
Hokkaido
4 Mar 1952 · 177 km away · intensity IX
33 deathsSevere damage ($5–24M)tsunami
- 1973M7.7
Hokkaido Island
17 Jun 1973 · 20 km away · intensity VIII
27 deaths$5 million damagetsunami
- 1894M7.9
Off Coast Of Honshu
22 Mar 1894 · 74 km away · intensity IX
1 deathModerate damage ($1–5M)tsunami
- 1938M6.1
E. Hokkaido Island, Japan
28 May 1938 · 119 km away
1 deathLimited damage (under $1M)tsunami
- 1958M8.3
Kuril Islands
6 Nov 1958 · 285 km away · intensity X
Moderate damage ($1–5M)tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.