Reviewed by USGSIndonesia107y ago
M6.6 earthquake 249 km NW of Sabang, Indonesia
Saturday, March 5, 1921, 06:24:18 UTC · 7.401°N, 93.638°E
A magnitude 6.6 earthquake struck 249 km NW of Sabang, Indonesia on Saturday, March 5, 1921, 06:24:18 UTC, at a depth of 20.0 km (shallow). It is the strongest earthquake within 300 km since an M6.8 on January 20, 1917.
- Magnitude
- 6.6
- Strong · mw
- Depth
- 20 km
- Shallow
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- VII
- Very 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
112 kilotons of TNT
That is about 7 times the Hiroshima bomb. It released about 234 times the energy of a magnitude 5.0.
Tectonic setting
93 km
from the nearest mapped plate boundary, between the Sunda and Burma plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
20 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 4 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 6.8238 km WNW of Sabang, IndonesiaJanuary 20, 1917 · 45 km S of this epicenter
- 6.5253 km WNW of Sabang, IndonesiaNovember 21, 1907 · 111 km SW of this epicenter
- 6.3273 km SSE of Port Blair, IndiaOctober 21, 1916 · 217 km N of this epicenter
- 6.2Nicobar Islands, India regionAugust 12, 1915 · 234 km W of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 5 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1881M7.9
Andaman I,Nicobar I
31 Dec 1881 · 182 km away
Severe damage ($5–24M)tsunami
- 1847
Little Nicobar Island
31 Oct 1847 · 8 km away · intensity X
Limited damage (under $1M)tsunami
- 1885
Banda Atjeh
14 Dec 1885 · 276 km away
tsunami
- 1886
Koeta Radja (Atjeh)
31 Jan 1886 · 272 km away
tsunami
- 1888
Sumatera: Breueh Island
21 Mar 1888 · 233 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.