M3.9 earthquake 41 km N of Jiangyou, China

Wednesday, July 9, 2008, 21:20:31 UTC · 32.136°N, 104.790°E

A magnitude 3.9 earthquake struck 41 km N of Jiangyou, China on Wednesday, July 9, 2008, 21:20:31 UTC, at a depth of 10.0 km (shallow).

Magnitude: 3.9; Minor · mb
Depth: 10 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

11 tons of TNT

That is about 1/1,410 of the Hiroshima bomb. A magnitude 5.0 releases about 45 times more energy.

Tectonic setting

344 km

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

Depth: shallow

10 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 11 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M5.7 on August 1, 2008. 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 91 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 34 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 121,784 recorded deaths. The most severe:

2008M7.9
Sichuan Province
12 May 2008 · 184 km away · intensity IX
87,652 deaths$86 billion damagetsunami
1879M8.0
Gansu Province
1 Jul 1879 · 119 km away · intensity XI
22,000 deathsExtreme damage ($25M+)
1933M7.4
Sichuan Province
25 Aug 1933 · 108 km away · intensity X
9,300 deathsExtreme damage ($25M+)
1765M6.5
Gansu Province: Wushan, Gangu
2 Sep 1765 · 297 km away · intensity IX
2,068 deathsExtreme damage ($25M+)
1881M6.5
Gansu Province
20 Jul 1881 · 164 km away · intensity VIII
480 deathsSevere damage ($5–24M)
1936M6.0
Gansu Province
1 Aug 1936 · 245 km away · intensity VIII
115 deathsSevere damage ($5–24M)

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

Nearby trackers