M7.4 earthquake 56 km NW of Sinabang, Indonesia

Wednesday, February 20, 2008, 08:08:30 UTC · 2.768°N, 95.964°E

A magnitude 7.4 earthquake struck 56 km NW of Sinabang, Indonesia on Wednesday, February 20, 2008, 08:08:30 UTC, at a depth of 26.0 km (shallow). USGS received 161 “Did You Feel It?” reports, with a maximum reported intensity of V (moderate). It is the strongest earthquake within 300 km since an M8.6 on March 28, 2005.

Magnitude: 7.4; Major · mwc
Depth: 26 km; Shallow
Felt reports: 161; Max intensity V
Est. shaking: VII; Very strong (ShakeMap)
PAGER alert: None; Not issued
Tsunami: No flag; USGS feed

Outlined circle: this earthquakeDashed circle: 200 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)

In context

How big was it, and why here?

Energy released

1.9 megatons of TNT

That is about 126 times the Hiroshima bomb. It released about 3,981 times the energy of a magnitude 5.0.

Tectonic setting

39 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

26 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
Kuala Lumpur, Kuala Lumpur, Malaysia	III · Weak	23	640 km
Gelugor, Pulau Pinang, Malaysia	III · Weak	23	586 km
Medan, Sumatera Utara, Indonesia	IV · Light	16	315 km
Banda Aceh, Aceh, Indonesia	IV · Light	14	316 km
Georgetown, Pulau Pinang, Malaysia	III · Weak	11	562 km
Sungai Ara, Pulau Pinang, Malaysia	III · Weak	11	556 km
Petaling Jaya, Selangor, Malaysia	III · Weak	10	630 km
Malé, Malé, Maldives	III · Weak	5	2501 km
Singapore, _no region, Singapore	II · Weak	5	892 km
Nibong Tebal, Pulau Pinang, Malaysia	III · Weak	4	568 km
Perai, Pulau Pinang, Malaysia	III · Weak	4	569 km
Tanjong Tokong, Pulau Pinang, Malaysia	III · Weak	4	567 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 200 km

USGS lists 34 M2.5+ earthquakes within 200 km in the following 30 days; the largest was M6.0 on March 15, 2008. 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 579 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 231,431 recorded deaths. The most severe:

2004M9.1
Sumatra: Aceh: Off West Coast
26 Dec 2004 · 59 km away
227,899 deaths$10 billion damagetsunami
1907M8.2
Nw Sumatra: Gunungsitoli, Barus
4 Jan 1907 · 49 km away
2,188 deathsSevere damage ($5–24M)tsunami
2005M8.6
Sumatera: Sw
28 Mar 2005 · 148 km away
1,319 deaths$37 million damagetsunami
1936
N Sumatera: Tapanuli, Karo
9 Sep 1936 · 189 km away · intensity VIII
17 deathsModerate damage ($1–5M)
2002M7.3
Sumatera: Simeulue
2 Nov 2002 · 15 km away
3 deathsSevere damage ($5–24M)
2008M7.4
Sumatera: Aceh Province
20 Feb 2008 · 0 km away
3 deaths

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

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