M8.1 earthquake 2007 Solomon Islands Earthquake

Sunday, April 1, 2007, 20:39:58 UTC · 8.466°S, 157.043°E

A magnitude 8.1 earthquake struck 2007 Solomon Islands Earthquake on Sunday, April 1, 2007, 20:39:58 UTC, at a depth of 24.0 km (shallow). USGS received 19 “Did You Feel It?” reports, with a maximum reported intensity of IX (violent). No earthquake of this size or larger appears within 300 km in the USGS catalog since 1900.

Magnitude: 8.1; Great · mwc
Depth: 24 km; Shallow
Felt reports: 19; Max intensity IX
Est. shaking: VIII; Severe (ShakeMap)
PAGER alert: None; Not issued
Tsunami: No flag; USGS feed

Outlined circle: this earthquakeDashed circle: 400 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)

In context

How big was it, and why here?

Energy released

21 megatons of TNT

That is about 1,415 times the Hiroshima bomb. It released about 44,668 times the energy of a magnitude 5.0.

Tectonic setting

22 km

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

Depth: shallow

24 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
Honiara, Guadalcanal, Solomon Islands	V · Moderate	6	333 km
Gizo, Western, Solomon Islands	IX · Violent	1	51 km
Sydney, New South Wales, Australia	II · Weak	1	2877 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 400 km

USGS lists 420 M2.5+ earthquakes within 400 km in the following 30 days; the largest was M6.9 on April 1, 2007. 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 599 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 12 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 69 recorded deaths. The most severe:

2007M8.1
Solomon Islands
1 Apr 2007 · 0 km away
52 deathsSevere damage ($5–24M)tsunami
1939M7.9
Solomon Islands
30 Apr 1939 · 258 km away
12 deathsModerate damage ($1–5M)tsunami
1939M7.7
Bougainville Island
30 Jan 1939 · 239 km away
5 deathsModerate damage ($1–5M)tsunami
1959M7.3
Solomon Islands
17 Aug 1959 · 157 km away
Severe damage ($5–24M)tsunami
1974M7.1
Solomon Islands
1 Feb 1974 · 198 km away · intensity VI
Moderate damage ($1–5M)tsunami
1926M7.5
Guadalcanal
25 Jan 1926 · 297 km away
Limited damage (under $1M)tsunami

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

Nearby trackers