M7.3 earthquake 163 km ENE of Petropavlovsk-Kamchatsky, Russia

Friday, February 2, 1923, 05:07:48 UTC · 53.739°N, 160.813°E

A magnitude 7.3 earthquake struck 163 km ENE of Petropavlovsk-Kamchatsky, Russia on Friday, February 2, 1923, 05:07:48 UTC, at a depth of 35.0 km (shallow). It is the strongest earthquake within 300 km since an M7.3 on July 31, 1915.

Magnitude: 7.3; Major · mw
Depth: 35 km; Shallow
Felt reports: 0; Did You Feel It?
Est. shaking: VI; Strong (ShakeMap)
PAGER alert: None; Not issued
Tsunami: No flag; USGS feed

Outlined circle: this earthquakeDashed circle: 200 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)

In context

How big was it, and why here?

Energy released

1.2 megatons of TNT

That is about 80 times the Hiroshima bomb. It released about 2,541 times the energy of a magnitude 5.0.

Tectonic setting

128 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: 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 200 km

USGS lists 5 M2.5+ earthquakes within 200 km in the following 30 days; the largest was M8.4 on February 3, 1923. 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 18 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 14 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 3 recorded deaths. The most severe:

1923M8.4
Kamchatka
3 Feb 1923 · 86 km away · intensity XI
3 deaths$2 million damagetsunami
1841M8.4
Off Kamchatka
17 May 1841 · 270 km away · intensity XI
Moderate damage ($1–5M)tsunami
1904M8.3
Off Kamchatka
25 Jun 1904 · 228 km away · intensity X
Limited damage (under $1M)tsunami
1904M8.1
Off Kamchatka
25 Jun 1904 · 228 km away · intensity X
Limited damage (under $1M)tsunami
1923M7.7
Kamchatka Peninsula
24 Feb 1923 · 174 km away
Limited damage (under $1M)
1827
Kamchatka
9 Aug 1827 · 174 km away
Limited damage (under $1M)tsunami

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

Nearby trackers