M4.7 earthquake 128 km SE of Kuril’sk, Russia

Thursday, April 20, 1978, 13:40:41 UTC · 44.417°N, 149.036°E

A magnitude 4.7 earthquake struck 128 km SE of Kuril’sk, Russia on Thursday, April 20, 1978, 13:40:41 UTC, at a depth of 33.0 km (shallow). It is the strongest earthquake within 300 km since an M4.7 on April 19, 1978.

Magnitude: 4.7; Light · mb
Depth: 33 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 earthquakeDashed circle: 50 km aftershock search area

In context

How big was it, and why here?

Energy released

169 tons of TNT

That is about 1/89 of the Hiroshima bomb. A magnitude 5.0 releases about 3 times more energy.

Tectonic setting

77 km

from the nearest mapped plate boundary, between the Okhotsk and Pacific plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.

Depth: shallow

33 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 50 km

USGS lists 10 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M5.4 on April 26, 1978. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.

Regional history

Past M5+ earthquakes within 300 km

USGS lists 855 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

History · NOAA

Deadliest earthquakes in this area

NOAA’s significant-earthquake database lists 40 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 62 recorded deaths. The most severe:

1973M7.7
Hokkaido Island
17 Jun 1973 · 293 km away · intensity VIII
27 deaths$5 million damagetsunami
1918M8.3
Kuril Islands
7 Sep 1918 · 228 km away
23 deathsModerate damage ($1–5M)tsunami
1780M7.5
Kuril Islands
29 Jun 1780 · 197 km away
12 deathsLimited damage (under $1M)tsunami
1958M8.3
Kuril Islands
6 Nov 1958 · 41 km away · intensity X
Moderate damage ($1–5M)tsunami
1969M8.2
Shikotan Island, Kurilskiye
11 Aug 1969 · 128 km away · intensity IX
Moderate damage ($1–5M)tsunami
1978M7.5
Kuril Islands
6 Dec 1978 · 196 km away · intensity VIII
Moderate damage ($1–5M)

NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.

Nearby trackers