Reviewed by USGSChina54y ago
M4.9 earthquake 258 km NW of Kangding, China
Wednesday, February 21, 1973, 08:23:15 UTC · 31.666°N, 100.062°E
A magnitude 4.9 earthquake struck 258 km NW of Kangding, China on Wednesday, February 21, 1973, 08:23:15 UTC, at a depth of 33.0 km (shallow). It is the strongest earthquake within 300 km since an M4.9 on February 16, 1973.
- Magnitude
- 4.9
- 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
338 tons of TNT
That is about 1/45 of the Hiroshima bomb. A magnitude 5.0 releases about 1 times more energy.
Tectonic setting
472 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 50 km
USGS lists 1 M2.5+ earthquake within 50 km in the following 30 days; the largest was M5.1 on March 21, 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 46 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.6Qinghai-Sichuan border region, ChinaMarch 17, 1947 · 211 km N of this epicenter
- 7.4203 km NW of Kangding, ChinaFebruary 6, 1973 · 58 km SE of this epicenter
- 7.3151 km W of Kangding, ChinaMay 25, 1948 · 174 km S of this epicenter
- 7.1150 km WNW of Kangding, ChinaAugust 30, 1904 · 121 km SE of this epicenter
- 7.119 km WSW of Kangding, ChinaApril 14, 1955 · 250 km SE of this epicenter
- 7.0184 km NW of Kangding, ChinaMarch 24, 1923 · 77 km SE of this epicenter
- 6.8143 km WSW of Kangding, ChinaFebruary 9, 1908 · 257 km S of this epicenter
- 6.5128 km NNW of Kangding, ChinaMay 29, 1919 · 157 km E of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 23 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 13,236 recorded deaths. The most severe:
- 1923M7.3
Sichuan Province
24 Mar 1923 · 91 km away · intensity X
4,800 deathsSevere damage ($5–24M)
- 1816M6.5
Sichuan Province
8 Dec 1816 · 67 km away · intensity VIII
2,854 deathsSevere damage ($5–24M)
- 1870M7.3
Sichuan Province: Batang
11 Apr 1870 · 211 km away · intensity X
2,300 deathsExtreme damage ($25M+)
- 1948M7.3
Sichuan Province
25 May 1948 · 244 km away · intensity X
800 deathsSevere damage ($5–24M)
- 1811M6.5
Sichuan Province: E. Of Ganze
27 Sep 1811 · 23 km away · intensity VIII
480 deathsModerate damage ($1–5M)
- 1786M7.5
Sichuan Province: S Of Kangding
1 Jun 1786 · 285 km away · intensity IX
435 deathsSevere damage ($5–24M)
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.