M4.3 earthquake off the west coast of northern Sumatra

Wednesday, September 28, 2005, 06:22:47 UTC · 4.563°N, 94.929°E

A magnitude 4.3 earthquake struck off the west coast of northern Sumatra on Wednesday, September 28, 2005, 06:22:47 UTC, at a depth of 30.0 km (shallow).

Magnitude: 4.3; 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

43 tons of TNT

That is about 1/354 of the Hiroshima bomb. A magnitude 5.0 releases about 11 times more energy.

Tectonic setting

129 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 7 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M5.9 on October 11, 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 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 23 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 230,114 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 · 220 km away
2,188 deathsSevere damage ($5–24M)tsunami
1967M6.1
N Sumatera,Malay Peninsula
12 Apr 1967 · 283 km away
14 deathsSevere damage ($5–24M)tsunami
1936M7.3
Banda Aceh,Lhok Sukon,Lhoksemawe
23 Aug 1936 · 173 km away · intensity VIII
9 deathsModerate damage ($1–5M)tsunami
2002M7.3
Sumatera: Simeulue
2 Nov 2002 · 232 km away
3 deathsSevere damage ($5–24M)
1990M6.8
N Sumatera, Blangkejeren, Kutacane
15 Nov 1990 · 290 km away
1 death$2 million damage

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

Nearby trackers