M7.4 earthquake 203 km NW of Kangding, China

Tuesday, February 6, 1973, 10:37:10 UTC · 31.398°N, 100.581°E

A magnitude 7.4 earthquake struck 203 km NW of Kangding, China on Tuesday, February 6, 1973, 10:37:10 UTC, at a depth of 33.0 km (shallow). It is the strongest earthquake within 300 km since an M7.6 on March 17, 1947.

Magnitude: 7.4; Major · ms
Depth: 33 km; Shallow
Felt reports: 0; Did You Feel It?
Est. shaking: IX; Violent (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

1.9 megatons of TNT

That is about 126 times the Hiroshima bomb. It released about 3,981 times the energy of a magnitude 5.0.

Tectonic setting

478 km

from the nearest mapped plate boundary, between the Eurasian and Indian plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.

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 200 km

USGS lists 5 M2.5+ earthquakes within 200 km in the following 30 days; the largest was M5.8 on February 7, 1973. 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 44 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 26 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 22,738 recorded deaths. The most severe:

1933M7.4
Sichuan Province
25 Aug 1933 · 299 km away · intensity X
9,300 deathsExtreme damage ($25M+)
1923M7.3
Sichuan Province
24 Mar 1923 · 41 km away · intensity X
4,800 deathsSevere damage ($5–24M)
1816M6.5
Sichuan Province
8 Dec 1816 · 11 km away · intensity VIII
2,854 deathsSevere damage ($5–24M)
1870M7.3
Sichuan Province: Batang
11 Apr 1870 · 217 km away · intensity X
2,300 deathsExtreme damage ($25M+)
1948M7.3
Sichuan Province
25 May 1948 · 211 km away · intensity X
800 deathsSevere damage ($5–24M)
1811M6.5
Sichuan Province: E. Of Ganze
27 Sep 1811 · 43 km away · intensity VIII
480 deathsModerate damage ($1–5M)

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

Nearby trackers