M4.2 earthquake 260 km W of Sabang, Indonesia

Friday, January 21, 2005, 12:43:13 UTC · 5.814°N, 92.965°E

A magnitude 4.2 earthquake struck 260 km W of Sabang, Indonesia on Friday, January 21, 2005, 12:43:13 UTC, at a depth of 30.0 km (shallow).

Magnitude: 4.2; Light · 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

30 tons of TNT

That is about 1/500 of the Hiroshima bomb. A magnitude 5.0 releases about 16 times more energy.

Tectonic setting

49 km

from the nearest mapped plate boundary, between the Burma and Indian plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.

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 13 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M5.5 on February 3, 2005. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.

Regional history

Past M5+ earthquakes within 300 km

USGS lists 333 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

History · NOAA

Deadliest earthquakes in this area

NOAA’s significant-earthquake database lists 13 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 9 recorded deaths. The most severe:

1936M7.3
Banda Aceh,Lhok Sukon,Lhoksemawe
23 Aug 1936 · 194 km away · intensity VIII
9 deathsModerate damage ($1–5M)tsunami
1983M6.6
Sumatera: Banda Aceh
4 Apr 1983 · 195 km away · intensity VII
$1 million damage
1982M6.3
Little Nicobar Island
20 Jan 1982 · 170 km away · intensity VIII
Moderate damage ($1–5M)
2005M7.2
Andaman Islands, Nicobar Islands
24 Jul 2005 · 249 km away
Limited damage (under $1M)
1847
Little Nicobar Island
31 Oct 1847 · 186 km away · intensity X
Limited damage (under $1M)tsunami
1955M7.3
Little Nicobar Island
17 May 1955 · 138 km away
tsunami

NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.

Nearby trackers