M5.1 earthquake 191 km SW of Sibolga, Indonesia

Sunday, July 31, 2005, 12:18:22 UTC · 0.348°N, 97.764°E

A magnitude 5.1 earthquake struck 191 km SW of Sibolga, Indonesia on Sunday, July 31, 2005, 12:18:22 UTC, at a depth of 26.0 km (shallow). It is the strongest earthquake within 300 km since an M5.3 on July 30, 2005.

Magnitude: 5.1; Moderate · mwc
Depth: 26 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: 75 km aftershock search area

In context

How big was it, and why here?

Energy released

674 tons of TNT

That is about 1/22 of the Hiroshima bomb. It released about 1 times the energy of a magnitude 5.0.

Tectonic setting

86 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

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

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 75 km

USGS lists 9 M2.5+ earthquakes within 75 km in the following 30 days; the largest was M5.3 on August 29, 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 328 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 15 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 3,676 recorded deaths. The most severe:

2005M8.6
Sumatera: Sw
28 Mar 2005 · 206 km away
1,319 deaths$37 million damagetsunami
1861M8.5
Lagundi, Simuk, Tello I
16 Feb 1861 · 153 km away · intensity IX
1,105 deathsModerate damage ($1–5M)tsunami
1861M7.0
Sw. Sumatra
9 Mar 1861 · 46 km away
950 deathsSevere damage ($5–24M)tsunami
1797M8.0
Sw. Sumatra
10 Feb 1797 · 143 km away · intensity IX
300 deathsModerate damage ($1–5M)tsunami
1987M6.6
Sumatera: N, Tarutung-Lake Toba,
25 Apr 1987 · 244 km away
2 deaths$1 million damage
1843M7.3
Sw. Sumatra
5 Jan 1843 · 131 km away · intensity XI
Severe damage ($5–24M)tsunami

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

Nearby trackers