Reviewed by USGSIndonesia21y ago
M3.8 earthquake 89 km S of Singkil, Indonesia
Friday, October 21, 2005, 02:14:26 UTC · 1.494°N, 97.644°E
A magnitude 3.8 earthquake struck 89 km S of Singkil, Indonesia on Friday, October 21, 2005, 02:14:26 UTC, at a depth of 30.0 km (shallow).
- Magnitude
- 3.8
- Minor · mb
- Depth
- 30 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
8 tons of TNT
That is about 1/1,992 of the Hiroshima bomb. A magnitude 5.0 releases about 63 times more energy.
Tectonic setting
105 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
30 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 3 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M4.2 on November 8, 2005. 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 438 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 · 272 km NW of this epicenter
- 8.678 km WSW of Singkil, IndonesiaMarch 28, 2005 · 89 km NW of this epicenter
- 8.2The 1907 Sumatra Earthquake and TsunamiJanuary 4, 1907 · 269 km NW of this epicenter
- 7.6212 km W of Pariaman, IndonesiaDecember 28, 1935 · 208 km S of this epicenter
- 7.450 km NW of Sinabang, IndonesiaNovember 2, 2002 · 228 km NW of this epicenter
- 7.1190 km SSW of Sibolga, IndonesiaNovember 17, 1984 · 150 km S of this epicenter
- 7.186 km WSW of Pangkalan Brandan, IndonesiaSeptember 19, 1936 · 243 km N of this epicenter
- 7.085 km SSE of Meulaboh, IndonesiaJune 20, 1976 · 258 km NW of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 21 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 233,784 recorded deaths. The most severe:
- 2004M9.1
Sumatra: Aceh: Off West Coast
26 Dec 2004 · 272 km away
227,899 deaths$10 billion damagetsunami
- 1907M8.2
Nw Sumatra: Gunungsitoli, Barus
4 Jan 1907 · 269 km away
2,188 deathsSevere damage ($5–24M)tsunami
- 2005M8.6
Sumatera: Sw
28 Mar 2005 · 89 km away
1,319 deaths$37 million damagetsunami
- 1861M8.5
Lagundi, Simuk, Tello I
16 Feb 1861 · 278 km away · intensity IX
1,105 deathsModerate damage ($1–5M)tsunami
- 1861M7.0
Sw. Sumatra
9 Mar 1861 · 170 km away
950 deathsSevere damage ($5–24M)tsunami
- 1797M8.0
Sw. Sumatra
10 Feb 1797 · 224 km away · intensity IX
300 deathsModerate damage ($1–5M)tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.