M9.1 earthquake 2004 Sumatra - Andaman Islands Earthquake

Sunday, December 26, 2004, 00:58:53 UTC · 3.295°N, 95.982°E

A magnitude 9.1 earthquake struck 2004 Sumatra - Andaman Islands Earthquake on Sunday, December 26, 2004, 00:58:53 UTC, at a depth of 30.0 km (shallow). USGS received 5 “Did You Feel It?” reports, with a maximum reported intensity of IX (violent). No earthquake of this size or larger appears within 300 km in the USGS catalog since 1900.

Magnitude: 9.1; Epic · mw
Depth: 30 km; Shallow
Felt reports: 5; Max intensity IX
Est. shaking: VIII; Severe (ShakeMap)
PAGER alert: None; Not issued
Tsunami: No flag; USGS feed

Outlined circle: this earthquakeDashed circle: 400 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)

In context

How big was it, and why here?

Energy released

674 megatons of TNT

That is about 44,736 times the Hiroshima bomb. It released about 1,412,538 times the energy of a magnitude 5.0.

Tectonic setting

19 km

from the nearest mapped plate boundary, between the Cocos and Nazca 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

Reports sent by people to USGS, grouped by place (most reports first). Intensity uses the Modified Mercalli scale (I–X): what people felt, not the magnitude.

Place	Intensity	Reports	Distance
Meulaboh, Aceh, Indonesia	IX · Violent	1	99 km

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 400 km

USGS lists 494 M2.5+ earthquakes within 400 km in the following 30 days; the largest was M6.1 on January 9, 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 256 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 21 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 230,122 recorded deaths. The most severe:

2004M9.1
Sumatra: Aceh: Off West Coast
26 Dec 2004 · 0 km away
227,899 deaths$10 billion damagetsunami
1907M8.2
Nw Sumatra: Gunungsitoli, Barus
4 Jan 1907 · 85 km away
2,188 deathsSevere damage ($5–24M)tsunami
1936
N Sumatera: Tapanuli, Karo
9 Sep 1936 · 170 km away · intensity VIII
17 deathsModerate damage ($1–5M)
1967M6.1
N Sumatera,Malay Peninsula
12 Apr 1967 · 285 km away
14 deathsSevere damage ($5–24M)tsunami
2002M7.3
Sumatera: Simeulue
2 Nov 2002 · 54 km away
3 deathsSevere damage ($5–24M)
1990M6.8
N Sumatera, Blangkejeren, Kutacane
15 Nov 1990 · 177 km away
1 death$2 million damage

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

Nearby trackers