Reviewed by USGSIndonesia18y ago
M3.9 earthquake 33 km SW of Sinabang, Indonesia
Monday, October 20, 2008, 21:22:50 UTC · 2.313°N, 96.133°E
A magnitude 3.9 earthquake struck 33 km SW of Sinabang, Indonesia on Monday, October 20, 2008, 21:22:50 UTC, at a depth of 35.0 km (shallow).
- Magnitude
- 3.9
- Minor · mb
- Depth
- 35 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
11 tons of TNT
That is about 1/1,410 of the Hiroshima bomb. A magnitude 5.0 releases about 45 times more energy.
Tectonic setting
70 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
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 50 km
USGS lists 2 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M4.9 on November 14, 2008. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 573 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 9.12004 Sumatra - Andaman Islands EarthquakeDecember 26, 2004 · 110 km N of this epicenter
- 8.678 km WSW of Singkil, IndonesiaMarch 28, 2005 · 111 km E of this epicenter
- 8.2The 1907 Sumatra Earthquake and TsunamiJanuary 4, 1907 · 78 km NW of this epicenter
- 7.5209 km WSW of Sinabang, IndonesiaNovember 21, 1969 · 179 km W of this epicenter
- 7.450 km NW of Sinabang, IndonesiaNovember 2, 2002 · 57 km N of this epicenter
- 7.456 km NW of Sinabang, IndonesiaFebruary 20, 2008 · 54 km N of this epicenter
- 7.186 km WSW of Pangkalan Brandan, IndonesiaSeptember 19, 1936 · 221 km NE of this epicenter
- 7.040 km NE of Meulaboh, IndonesiaAugust 3, 1935 · 232 km N of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 17 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 231,431 recorded deaths. The most severe:
- 2004M9.1
Sumatra: Aceh: Off West Coast
26 Dec 2004 · 110 km away
227,899 deaths$10 billion damagetsunami
- 1907M8.2
Nw Sumatra: Gunungsitoli, Barus
4 Jan 1907 · 78 km away
2,188 deathsSevere damage ($5–24M)tsunami
- 2005M8.6
Sumatera: Sw
28 Mar 2005 · 111 km away
1,319 deaths$37 million damagetsunami
- 1936
N Sumatera: Tapanuli, Karo
9 Sep 1936 · 201 km away · intensity VIII
17 deathsModerate damage ($1–5M)
- 2002M7.3
Sumatera: Simeulue
2 Nov 2002 · 57 km away
3 deathsSevere damage ($5–24M)
- 2008M7.4
Sumatera: Aceh Province
20 Feb 2008 · 54 km away
3 deaths
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.