M4.0 earthquake 40 km WSW of Jiangyou, China

Thursday, October 2, 2008, 22:37:42 UTC · 31.686°N, 104.301°E

A magnitude 4.0 earthquake struck 40 km WSW of Jiangyou, China on Thursday, October 2, 2008, 22:37:42 UTC, at a depth of 10.0 km (shallow).

Magnitude: 4.0; Light · 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

15 tons of TNT

That is about 1/998 of the Hiroshima bomb. A magnitude 5.0 releases about 32 times more energy.

Tectonic setting

327 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 12 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M4.8 on October 31, 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 115 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 39 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 121,070 recorded deaths. The most severe:

2008M7.9
Sichuan Province
12 May 2008 · 116 km away · intensity IX
87,652 deaths$86 billion damagetsunami
1879M8.0
Gansu Province
1 Jul 1879 · 172 km away · intensity XI
22,000 deathsExtreme damage ($25M+)
1933M7.4
Sichuan Province
25 Aug 1933 · 67 km away · intensity X
9,300 deathsExtreme damage ($25M+)
1881M6.5
Gansu Province
20 Jul 1881 · 215 km away · intensity VIII
480 deathsSevere damage ($5–24M)
1786M7.5
Sichuan Province: S Of Kangding
1 Jun 1786 · 297 km away · intensity IX
435 deathsSevere damage ($5–24M)
1893M6.8
Sichuan Province
29 Aug 1893 · 298 km away · intensity IX
288 deathsSevere damage ($5–24M)

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

Nearby trackers