M4.6 earthquake 27 km NNE of Yigo Village, Guam

Thursday, January 29, 2015, 08:42:08 UTC · 13.749°N, 145.018°E

A magnitude 4.6 earthquake struck 27 km NNE of Yigo Village, Guam on Thursday, January 29, 2015, 08:42:08 UTC, at a depth of 128.4 km (intermediate). USGS received 30 “Did You Feel It?” reports, with a maximum reported intensity of IV (light). It is the strongest earthquake within 300 km since an M5.0 on January 19, 2015.

Magnitude: 4.6; Light · mb
Depth: 128 km; Intermediate
Felt reports: 30; Max intensity IV
Est. shaking: —; No ShakeMap
PAGER alert: None; Not issued
Tsunami: No flag; USGS feed

Outlined circle: this earthquakeDashed circle: 50 km aftershock search area

In context

How big was it, and why here?

Energy released

120 tons of TNT

That is about 1/126 of the Hiroshima bomb. A magnitude 5.0 releases about 4 times more energy.

Tectonic setting

116 km

from the nearest mapped plate boundary, between the Philippine Sea and Mariana plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.

Depth: intermediate

128 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
96915<br>0.269	IV · Light	8	139 km
96911<br>0.285	III · Weak	6	133 km
96912<br>0.311	IV · Light	3	131 km
96929<br>0.311	III · Weak	3	130 km
96923<br>0.320	III · Weak	2	133 km
96913<br>0.330	V · Moderate	1	133 km
96916<br>0.330	IV · Light	1	143 km
96914<br>0.330	III · Weak	1	137 km
96927<br>0.330	III · Weak	1	134 km
96928<br>0.330	III · Weak	1	140 km
96919<br>0.330	II · Weak	1	135 km
96922<br>0.330	II · Weak	1	135 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 50 km

USGS lists 3 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M4.2 on February 23, 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 638 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 · 88 km away · intensity IX
$250 million damagetsunami
1849M7.5
Guam
25 Jan 1849 · 188 km away · intensity IX
Severe damage ($5–24M)tsunami
1909M8.0
Guam
9 Dec 1909 · 139 km away · intensity VIII
Moderate damage ($1–5M)tsunami
1892M7.5
Guam
16 May 1892 · 188 km away · intensity VIII
Moderate damage ($1–5M)tsunami
2001M7.0
Guam
12 Oct 2001 · 118 km away · intensity VIII
Moderate damage ($1–5M)
1825
Ladrones Island
Apr 1825 · 188 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