M7.1 earthquake 20 km SSW of Merizo Village, Guam

Friday, April 26, 2002, 16:06:07 UTC · 13.088°N, 144.619°E

A magnitude 7.1 earthquake struck 20 km SSW of Merizo Village, Guam on Friday, April 26, 2002, 16:06:07 UTC, at a depth of 85.7 km (intermediate). It is the strongest earthquake within 300 km since an M7.8 on August 8, 1993.

Magnitude: 7.1; Major · mwc
Depth: 86 km; Intermediate
Felt reports: 0; Did You Feel It?
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

674 kilotons of TNT

That is about 45 times the Hiroshima bomb. It released about 1,413 times the energy of a magnitude 5.0.

Tectonic setting

93 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

86 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

No “Did You Feel It?” reports have been published for this event yet. If you felt it, you can add your report on the USGS website.

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 5 M2.5+ earthquakes within 200 km in the following 30 days; the largest was M5.4 on May 21, 2002. 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 487 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 · 23 km away · intensity IX
$250 million damagetsunami
1849M7.5
Guam
25 Jan 1849 · 175 km away · intensity IX
Severe damage ($5–24M)tsunami
1909M8.0
Guam
9 Dec 1909 · 77 km away · intensity VIII
Moderate damage ($1–5M)tsunami
1892M7.5
Guam
16 May 1892 · 175 km away · intensity VIII
Moderate damage ($1–5M)tsunami
2001M7.0
Guam
12 Oct 2001 · 59 km away · intensity VIII
Moderate damage ($1–5M)
1825
Ladrones Island
Apr 1825 · 175 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