M5.1 earthquake 35 km N of Yigo Village, Guam

Saturday, April 25, 2015, 00:37:42 UTC · 13.850°N, 144.837°E

A magnitude 5.1 earthquake struck 35 km N of Yigo Village, Guam on Saturday, April 25, 2015, 00:37:42 UTC, at a depth of 140.2 km (intermediate). USGS received 21 “Did You Feel It?” reports, with a maximum reported intensity of IV (light). It is the strongest earthquake within 300 km since an M5.5 on March 22, 2015.

Magnitude: 5.1; Moderate · mb
Depth: 140 km; Intermediate
Felt reports: 21; Max intensity IV
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

95 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

140 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>0.293	III · Weak	5	145 km
96923<br>0.311	III · Weak	3	146 km
96915<br>0.311	II · Weak	3	149 km
96929<br>0.320	II · Weak	2	143 km
96916<br>0.330	IV · Light	1	155 km
96927<br>0.330	IV · Light	1	146 km
96922<br>0.330	III · Weak	1	147 km
96918<br>0.330	III · Weak	1	153 km
96912<br>0.330	III · Weak	1	143 km
96950<br>0.330	III · Weak	1	208 km
96952<br>0.330	III · Weak	1	227 km
96910<br>0.330	II · Weak	1	146 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 75 km

USGS lists 2 M2.5+ earthquakes within 75 km in the following 30 days; the largest was M4.3 on May 17, 2015. 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 656 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 · 97 km away · intensity IX
$250 million damagetsunami
1849M7.5
Guam
25 Jan 1849 · 167 km away · intensity IX
Severe damage ($5–24M)tsunami
1909M8.0
Guam
9 Dec 1909 · 151 km away · intensity VIII
Moderate damage ($1–5M)tsunami
1892M7.5
Guam
16 May 1892 · 167 km away · intensity VIII
Moderate damage ($1–5M)tsunami
2001M7.0
Guam
12 Oct 2001 · 130 km away · intensity VIII
Moderate damage ($1–5M)
1825
Ladrones Island
Apr 1825 · 167 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