M6.6 earthquake 56 km WSW of Linqiong, China

Saturday, April 20, 2013, 00:02:47 UTC · 30.308°N, 102.888°E

A magnitude 6.6 earthquake struck 56 km WSW of Linqiong, China on Saturday, April 20, 2013, 00:02:47 UTC, at a depth of 14.0 km (shallow). USGS received 100 “Did You Feel It?” reports, with a maximum reported intensity of VIII (severe). The USGS PAGER alert is red: high casualties and extensive damage are probable. It is the strongest earthquake within 300 km since an M7.9 on May 12, 2008.

Magnitude: 6.6; Strong · mww
Depth: 14 km; Shallow
Felt reports: 100; Max intensity VIII
Est. shaking: VIII; Severe (ShakeMap)
PAGER alert: Red; Impact estimate
Tsunami: No flag; USGS feed

Outlined circle: this earthquakeDashed circle: 100 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)

In context

How big was it, and why here?

Energy released

120 kilotons of TNT

That is about 8 times the Hiroshima bomb. It released about 251 times the energy of a magnitude 5.0.

Tectonic setting

294 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

14 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

Reports sent by people to USGS, grouped by place (most reports first). Intensity uses the Modified Mercalli scale (I–X): what people felt, not the magnitude.

Place	Intensity	Reports	Distance
Chengdu, Sichuan, China	V · Moderate	44	121 km
Chongqing, Chongqing, China	IV · Light	10	365 km
Xian, Shaanxi, China	III · Weak	9	716 km
Huayang, Sichuan, China	VI · Strong	7	104 km
Yaan, Sichuan, China	VIII · Severe	4	43 km
Linqiong, Sichuan, China	VIII · Severe	3	58 km
Xichang, Sichuan, China	III · Weak	3	275 km
Daxian, Sichuan, China	IV · Light	2	456 km
Kunming, Yunnan, China	III · Weak	2	583 km
Guiyang, Guizhou, China	II · Weak	2	558 km
Zhaotong, Yunnan, China	VI · Strong	1	341 km
Tianpeng, Sichuan, China	V · Moderate	1	126 km

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 populated area was estimated to feel noticeable shaking.

After the main event

Aftershocks within 100 km

USGS lists 49 M2.5+ earthquakes within 100 km in the following 30 days; the largest was M5.2 on April 21, 2013. 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 174 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 53 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 151,055 recorded deaths. The most severe:

2008M7.9
Sichuan Province
12 May 2008 · 89 km away · intensity IX
87,652 deaths$86 billion damagetsunami
1850M7.5
Sichuan: Xichang
12 Sep 1850 · 285 km away · intensity X
20,650 deathsExtreme damage ($25M+)
1974M7.1
Yunnan And Sichuan Provinces, Chao-T'Ung
10 May 1974 · 254 km away
20,000 deathsSevere damage ($5–24M)
1933M7.4
Sichuan Province
25 Aug 1933 · 198 km away · intensity X
9,300 deathsExtreme damage ($25M+)
1923M7.3
Sichuan Province
24 Mar 1923 · 224 km away · intensity X
4,800 deathsSevere damage ($5–24M)
1816M6.5
Sichuan Province
8 Dec 1816 · 242 km away · intensity VIII
2,854 deathsSevere damage ($5–24M)

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

Nearby trackers