Reviewed by USGSIndonesia107y ago
M6.7 earthquake 68 km SE of Singkil, Indonesia
Friday, April 1, 1921, 04:06:44 UTC · 1.795°N, 98.164°E
A magnitude 6.7 earthquake struck 68 km SE of Singkil, Indonesia on Friday, April 1, 1921, 04:06:44 UTC, at a depth of 35.0 km (shallow). It is the strongest earthquake within 300 km since an M6.9 on November 4, 1917.
- Magnitude
- 6.7
- Strong · mw
- Depth
- 35 km
- Shallow
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- VI
- Strong (ShakeMap)
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeColoured lines: estimated shaking intensity (USGS ShakeMap)
In context
How big was it, and why here?
Energy released
175 kilotons of TNT
That is about 12 times the Hiroshima bomb. It released about 367 times the energy of a magnitude 5.0.
Tectonic setting
157 km
from the nearest mapped plate boundary, between the Sunda and Burma plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.
Depth: shallow
35 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 100 km
USGS has not published any M2.5+ earthquake within 100 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 9 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 6.928 km NNE of Sinabang, IndonesiaNovember 4, 1917 · 209 km NW of this epicenter
- 6.860 km W of Sinabang, IndonesiaNovember 2, 1908 · 271 km W of this epicenter
- 6.7214 km SW of Sibolga, IndonesiaMay 29, 1914 · 185 km S of this epicenter
- 6.2126 km SW of Singkil, IndonesiaApril 3, 1915 · 125 km W of this epicenter
- 6.2134 km SW of Sinabang, IndonesiaMarch 17, 1920 · 290 km W of this epicenter
- 6.2251 km SSW of Singkil, IndonesiaOctober 29, 1913 · 217 km SW of this epicenter
- 6.2247 km SSW of Singkil, IndonesiaFebruary 12, 1918 · 225 km SW of this epicenter
- 6.159 km W of Kabanjahe, IndonesiaJuly 27, 1916 · 155 km N of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 8 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 1,250 recorded deaths. The most severe:
- 1861M7.0
Sw. Sumatra
9 Mar 1861 · 199 km away
950 deathsSevere damage ($5–24M)tsunami
- 1797M8.0
Sw. Sumatra
10 Feb 1797 · 220 km away · intensity IX
300 deathsModerate damage ($1–5M)tsunami
- 1843M7.3
Sw. Sumatra
5 Jan 1843 · 38 km away · intensity XI
Severe damage ($5–24M)tsunami
- 1892
Sumatra: Padangsidimpuan, Lake Toba
17 May 1892 · 168 km away · intensity VI
Moderate damage ($1–5M)tsunami
- 1861M7.0
Sw. Sumatra
26 Apr 1861 · 115 km away
tsunami
- 1852M6.8
Sumatra: Sibolga
11 Nov 1852 · 38 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.