M6.3 earthquake 87 km SE of Sinabang, Indonesia

Tuesday, April 25, 2006, 18:26:17 UTC · 1.994°N, 96.995°E

A magnitude 6.3 earthquake struck 87 km SE of Sinabang, Indonesia on Tuesday, April 25, 2006, 18:26:17 UTC, at a depth of 21.0 km (shallow). USGS received 2 “Did You Feel It?” reports, with a maximum reported intensity of IV (light). It is the strongest earthquake within 300 km since an M6.5 on November 19, 2005.

Magnitude: 6.3; Strong · mwc
Depth: 21 km; Shallow
Felt reports: 2; Max intensity IV
Est. shaking: VI; Strong (ShakeMap)
PAGER alert: None; Not issued
Tsunami: No flag; USGS feed

Outlined circle: this earthquakeDashed circle: 100 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)

In context

How big was it, and why here?

Energy released

43 kilotons of TNT

That is about 3 times the Hiroshima bomb. It released about 89 times the energy of a magnitude 5.0.

Tectonic setting

26 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

21 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
Sibolga, Sumatera Utara, Indonesia	IV · Light	1	201 km
Medan, Sumatera Utara, Indonesia	II · Weak	1	257 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 100 km

USGS lists 11 M2.5+ earthquakes within 100 km in the following 30 days; the largest was M5.2 on April 29, 2006. 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 479 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 232,379 recorded deaths. The most severe:

2004M9.1
Sumatra: Aceh: Off West Coast
26 Dec 2004 · 183 km away
227,899 deaths$10 billion damagetsunami
1907M8.2
Nw Sumatra: Gunungsitoli, Barus
4 Jan 1907 · 180 km away
2,188 deathsSevere damage ($5–24M)tsunami
2005M8.6
Sumatera: Sw
28 Mar 2005 · 16 km away
1,319 deaths$37 million damagetsunami
1861M7.0
Sw. Sumatra
9 Mar 1861 · 247 km away
950 deathsSevere damage ($5–24M)tsunami
1936
N Sumatera: Tapanuli, Karo
9 Sep 1936 · 177 km away · intensity VIII
17 deathsModerate damage ($1–5M)
2002M7.3
Sumatera: Simeulue
2 Nov 2002 · 137 km away
3 deathsSevere damage ($5–24M)

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

Nearby trackers