M4.6 earthquake 168 km SSW of Singkil, Indonesia

Sunday, July 31, 2005, 05:40:09 UTC · 0.967°N, 97.027°E

A magnitude 4.6 earthquake struck 168 km SSW of Singkil, Indonesia on Sunday, July 31, 2005, 05:40:09 UTC, at a depth of 18.1 km (shallow). It is the strongest earthquake within 300 km since an M4.7 on July 30, 2005.

Magnitude: 4.6; Light · mb
Depth: 18 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

120 tons of TNT

That is about 1/126 of the Hiroshima bomb. A magnitude 5.0 releases about 4 times more energy.

Tectonic setting

46 km

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

Depth: shallow

18 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 24 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M5.0 on August 13, 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 399 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 19 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 233,783 recorded deaths. The most severe:

2004M9.1
Sumatra: Aceh: Off West Coast
26 Dec 2004 · 284 km away
227,899 deaths$10 billion damagetsunami
1907M8.2
Nw Sumatra: Gunungsitoli, Barus
4 Jan 1907 · 253 km away
2,188 deathsSevere damage ($5–24M)tsunami
2005M8.6
Sumatera: Sw
28 Mar 2005 · 125 km away
1,319 deaths$37 million damagetsunami
1861M8.5
Lagundi, Simuk, Tello I
16 Feb 1861 · 225 km away · intensity IX
1,105 deathsModerate damage ($1–5M)tsunami
1861M7.0
Sw. Sumatra
9 Mar 1861 · 152 km away
950 deathsSevere damage ($5–24M)tsunami
1797M8.0
Sw. Sumatra
10 Feb 1797 · 244 km away · intensity IX
300 deathsModerate damage ($1–5M)tsunami

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

Nearby trackers