Reviewed by USGSChina50y ago
M4.9 earthquake 117 km NNW of Jiangyou, China
Wednesday, August 18, 1976, 03:26:12 UTC · 32.762°N, 104.279°E
A magnitude 4.9 earthquake struck 117 km NNW of Jiangyou, China on Wednesday, August 18, 1976, 03:26:12 UTC, at a depth of 33.0 km (shallow). It is the strongest earthquake within 300 km since an M5.0 on August 16, 1976.
- 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
428 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
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 6 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M6.7 on August 23, 1976. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
- 5.193 km NW of Jiangyou, China50y ago · 36 km S of this epicenter
- 4.380 km NW of Jiangyou, China50y ago · 46 km S of this epicenter
- 6.794 km NNW of Jiangyou, China50y ago · 31 km S of this epicenter
- 4.7110 km NNW of Jiangyou, China50y ago · 8 km S of this epicenter
- 6.499 km NNW of Jiangyou, China50y ago · 21 km S of this epicenter
- 5.4134 km NNW of Jiangyou, China50y ago · 17 km NW of this epicenter
Regional history
Past M5+ earthquakes within 300 km
USGS lists 30 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.4101 km WNW of Jiangyou, ChinaAugust 25, 1933 · 106 km SW of this epicenter
- 6.9121 km NNW of Jiangyou, ChinaAugust 16, 1976 · 11 km W of this epicenter
- 6.3146 km NW of Jiangyou, ChinaNovember 9, 1960 · 61 km W of this epicenter
- 6.2Qinghai-Sichuan border region, ChinaOctober 31, 1952 · 295 km W of this epicenter
- 6.261 km S of Tianshui, ChinaAugust 1, 1936 · 195 km NE of this epicenter
- 6.1127 km WNW of Jiangyou, ChinaMarch 14, 1938 · 102 km SW of this epicenter
- 6.1151 km NNW of Jiangyou, ChinaAugust 11, 1973 · 36 km NW of this epicenter
- 6.050 km NW of Deyang, ChinaFebruary 7, 1958 · 146 km S of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 22 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 107,115 recorded deaths. The most severe:
- 1718M7.5
Gansu Province
19 Jun 1718 · 263 km away · intensity X
73,000 deathsExtreme damage ($25M+)
- 1879M8.0
Gansu Province
1 Jul 1879 · 63 km away · intensity XI
22,000 deathsExtreme damage ($25M+)
- 1933M7.4
Sichuan Province
25 Aug 1933 · 106 km away · intensity X
9,300 deathsExtreme damage ($25M+)
- 1765M6.5
Gansu Province: Wushan, Gangu
2 Sep 1765 · 236 km away · intensity IX
2,068 deathsExtreme damage ($25M+)
- 1881M6.5
Gansu Province
20 Jul 1881 · 98 km away · intensity VIII
480 deathsSevere damage ($5–24M)
- 1936M6.0
Gansu Province
1 Aug 1936 · 207 km away · intensity VIII
115 deathsSevere damage ($5–24M)
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.