M7.7 earthquake 148 km NW of Sola, Vanuatu

Wednesday, October 7, 2009, 22:03:14 UTC · 13.006°S, 166.510°E

A magnitude 7.7 earthquake struck 148 km NW of Sola, Vanuatu on Wednesday, October 7, 2009, 22:03:14 UTC, at a depth of 45.0 km (shallow). USGS received 9 “Did You Feel It?” reports, with a maximum reported intensity of IV (light). It is the strongest earthquake within 300 km since an M7.7 on April 21, 1997.

Magnitude: 7.7; Major · mww
Depth: 45 km; Shallow
Felt reports: 9; Max intensity IV
Est. shaking: VII; Very strong (ShakeMap)
PAGER alert: None; Not issued
Tsunami: No flag; USGS feed

Outlined circle: this earthquakeDashed circle: 200 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)

In context

How big was it, and why here?

Energy released

5.4 megatons of TNT

That is about 355 times the Hiroshima bomb. It released about 11,220 times the energy of a magnitude 5.0.

Tectonic setting

60 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

45 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
Vila, Shefa, Vanuatu	II · Weak	2	560 km
Sola, Torba, Vanuatu	IV · Light	1	154 km
Luganville, Sanma, Vanuatu	IV · Light	1	289 km
Lakatoro, Malampa, Vanuatu	III · Weak	1	357 km
Port Olry, Sanma, Vanuatu	III · Weak	1	237 km
Apia, Apia Urban Area, Samoa	III · Weak	1	2355 km
Suva, Central, Fiji Islands	I · Not felt	1	1399 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 200 km

USGS lists 223 M2.5+ earthquakes within 200 km in the following 30 days; the largest was M7.8 on October 7, 2009. 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 1,589 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 30 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 1 recorded deaths. The most severe:

1971M7.1
Espiritu Santo, Port Vila
27 Oct 1971 · 287 km away · intensity VII
1 deathSevere damage ($5–24M)
1973M7.5
Espiritu Santo, Luganille
28 Dec 1973 · 162 km away · intensity VII
Moderate damage ($1–5M)
1910M7.2
Espiritu Santo
10 Nov 1910 · 111 km away
Moderate damage ($1–5M)tsunami
1973M7.2
Luganville, Lamap
29 Dec 1973 · 239 km away · intensity VIII
Moderate damage ($1–5M)
1990M6.4
Espiritu Santo
27 Jul 1990 · 281 km away · intensity V
Moderate damage ($1–5M)
2002M5.9
Mere Lava Island
27 Nov 2002 · 218 km away
Moderate damage ($1–5M)

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

Nearby trackers