M6.7 earthquake 43 km NW of Piti Village, Guam

Wednesday, September 17, 2014, 06:14:45 UTC · 13.764°N, 144.429°E

A magnitude 6.7 earthquake struck 43 km NW of Piti Village, Guam on Wednesday, September 17, 2014, 06:14:45 UTC, at a depth of 130.0 km (intermediate). USGS received 61 “Did You Feel It?” reports, with a maximum reported intensity of V (moderate). The USGS PAGER alert is green: low likelihood of casualties and damage. It is the strongest earthquake within 300 km since an M6.8 on May 9, 2008.

Tsunami flagUSGS sets this flag for large events in oceanic regions so tsunami warning centers review them. It does not by itself mean a tsunami occurred. Check tsunami.gov and local authorities for official messages.

Magnitude: 6.7; Strong · mww
Depth: 130 km; Intermediate
Felt reports: 61; Max intensity V
Est. shaking: V; Moderate (ShakeMap)
PAGER alert: Green; Impact estimate
Tsunami: Flag; Check tsunami.gov

Outlined circle: this earthquakeDashed circle: 100 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)

In context

How big was it, and why here?

Energy released

169 kilotons of TNT

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

Tectonic setting

53 km

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

Depth: intermediate

130 km

Intermediate-depth earthquakes usually break inside a plate that is sinking into the mantle. Shaking spreads over a wide area but is gentler at the epicenter than a shallow quake of the same size.

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
96911<br>0.248	V · Moderate	11	139 km
96913<br>0.269	IV · Light	8	139 km
96929<br>0.277	V · Moderate	7	141 km
96915<br>0.285	IV · Light	6	138 km
96912<br>0.285	IV · Light	6	139 km
96910<br>0.293	IV · Light	5	138 km
96923<br>0.311	V · Moderate	3	141 km
96952<br>0.311	III · Weak	3	249 km
96951<br>0.320	IV · Light	2	160 km
96922<br>0.320	IV · Light	2	138 km
96918<br>0.330	V · Moderate	1	141 km
Tamuning, Tamuning, Guam	IV · Light	1	139 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 populated area was estimated to feel noticeable shaking.

After the main event

Aftershocks within 100 km

USGS lists 7 M2.5+ earthquakes within 100 km in the following 30 days; the largest was M4.6 on September 26, 2014. 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 648 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 13 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:

1993M7.8
Tuman Bay, Apra Harbor
8 Aug 1993 · 96 km away · intensity IX
$250 million damagetsunami
1849M7.5
Guam
25 Jan 1849 · 125 km away · intensity IX
Severe damage ($5–24M)tsunami
1909M8.0
Guam
9 Dec 1909 · 154 km away · intensity VIII
Moderate damage ($1–5M)tsunami
1892M7.5
Guam
16 May 1892 · 125 km away · intensity VIII
Moderate damage ($1–5M)tsunami
2001M7.0
Guam
12 Oct 2001 · 134 km away · intensity VIII
Moderate damage ($1–5M)
1825
Ladrones Island
Apr 1825 · 125 km away · intensity VIII
Moderate damage ($1–5M)tsunami

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

Nearby trackers