How many earthquakes hit Guam?

The USGS catalog records 2,465 magnitude-4-and-above earthquakes in Guam since 2005, about 117 per year, plus 42 major (M6+) events catalogued back to 1900.

What was the largest earthquake in Guam?

The strongest catalogued earthquake in Guam measured magnitude 7.8. The average magnitude across the M4+ catalog is 4.5.

How does Guam rank for earthquakes?

Among U.S. states and territories, Guam ranks 3rd of 39 by catalogued M4+ activity - one of the most seismically active U.S. jurisdictions. On the M4+ activity ladder Northern Mariana Islands sits immediately above at 3,345 events and California sits immediately below at 885.

Where does this data come from?

All figures come from the USGS Comprehensive Earthquake Catalog (ComCat). M4+ counts cover 2005 onward; the significant-event series covers M6+ back to 1900.

U.S. state profile · USGS ComCat

Earthquakes in Guam

Guam has catalogued 2,465 M4+ earthquakes since 2005 (ranked 3rd of 39 U.S. states), with the strongest reaching magnitude M7.8.

Guam ranks 3rd of 39 U.S. states and territories by catalogued seismic activity - one of the most seismically active U.S. jurisdictions, averaging about 117 M4+ events a year alongside 42 significant M6+ earthquakes since 1900. Below: the full M6+ event history, magnitude and depth profile, and yearly trend.

Compiled by PlainQuake, Earthquake Data Editorial Process · August 26, 2026

2,465
M4+ events (since 2005): 42
Major M6+ (since 1900): M7.8
Strongest: ~117
M4+ per year

The verdict

Guam is among the more seismically active places worldwide, with 2,465 M4+ earthquakes logged since 2005 and 42 major M6+ events since 1900, the strongest reaching magnitude 7.8.

1917
busiest year (3 major events): 53 km
average recorded event depth: 71%
of events are shallow (<70 km, the most damaging kind)

Average catalogued magnitude is 4.5 - most events are moderate tremors felt but rarely damaging. On the M4+ activity ladder Northern Mariana Islands sits immediately above at 3,345 events and California sits immediately below at 885.

Catalog event strip

Event tape GU · Guam M4+ · 3rd/39

Guam · 2,465 M4+ · max M7.8 · 42 M6+

DEPTH 2,465
PHOTO 3rd/39
BUSY M7.8
SHAL 42
PCT near Northern Mariana Islands
VS-PEER 71% shallow

Stamps derive from this jurisdiction's USGS ComCat row (M4+ book, rank, peak magnitude, M6+ record, ladder neighbour, depth/peak year), not a hazard forecast. PlainQuake is informational only - not professional advice and not a substitute for official USGS guidance. See our disclaimer. Verify with USGS ComCat → · Read with methodology → · How earthquakes are measured → · Most active U.S. regions → · All state catalog rows → · States ranked →

Observed impact record

What ComCat observed after earthquakes in Guam

USGS recorded Modified Mercalli Intensity (MMI) for 9 events in this catalogued record; their average observed intensity was MMI 5.4. These are only events with an observation, not an estimate of future shaking or a safety rating.

MMI observations: 9
Average observed MMI: 5.4
PAGER alerts / tsunami flags: 3 / 1

Source: USGS Comprehensive Earthquake Catalog (ComCat) GeoJSON impact fields. Missing MMI, alert, and tsunami values remain unreported rather than being treated as zero.

M4+ catalog count for Guam and nearest-count peers. Source: USGS ComCat, 2005–present.

Where Guam sits in the catalog

Rank 3rd of 39 tracked U.S. states and territories (92th percentile by M4+ count since 2005). On the M4+ activity ladder Northern Mariana Islands sits immediately above at 3,345 events and California sits immediately below at 885.

Northern Mariana Islands - next more active (3,345 M4+)
California - next less active (885 M4+)

Guam's M4+ count vs. every tracked state

Total catalogued M4+ events since 2005, USGS ComCat

2,465 Top 8% higher than 92% of 39 states

Each bar is a 100-wide band; taller bars hold more states. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count, share, and where it sits relative to this entry.

Source USGS Comprehensive Earthquake Catalog (ComCat) · 2005-present

1997

2
1998

2
1999

1
2000

2
2001

1
2002

1
2005

1
2008

1
2010

1
2014

1
2022

1
2025

1

What this shows Guam's most active year for major earthquakes was 1917 (3 M6+ events). Major-quake counts track the episodic release of tectonic stress, not a smooth trend.

Magnitude distribution of major events

Breakdown of the 42 significant (M6+) earthquakes on record for Guam.

M7.0–7.9

16.7%

M6.0–6.9

83.3%

Depth of major earthquakes

Hypocentral depth of the 42 M6+ events, shallow quakes shake the surface hardest. Average depth: 53 km.

Depth distribution of Guam's M6+ events, USGS ComCat

Shallow (<70 km)

71% of events

Intermediate (70–300 km)

28.6% of events

Deep (>300 km)

0.0% of events

Seismic hazard context

Catalogued counts on this page are history, not a building-code hazard map. Guam's latest M4+ catalog entry is dated Aug 8, 2026. For the national PGA design-basis tiers, see the seismic risk maps guide or the USGS National Seismic Hazard Model.

Strongest earthquakes in Guam

The 10 most powerful events on record (USGS, since 1900).

Mag	Location	Depth	Date
7.8	32 km S of Inarajan Village, Guam	59.3 km	Aug 8, 1993
7.2	265 km S of Merizo Village, Guam	15.0 km	Jan 28, 1931
7.1	261 km S of Merizo Village, Guam	15.0 km	May 9, 1917
7.1	20 km SSW of Merizo Village, Guam	85.7 km	Apr 26, 2002
7.0	98 km SSE of Inarajan Village, Guam	15.0 km	Dec 9, 1909
7.0	69 km SSE of Inarajan Village, Guam	37.0 km	Oct 12, 2001
7.0	32 km NNE of Yigo Village, Guam	180.0 km	Oct 26, 1912
6.8	181 km WSW of Merizo Village, Guam	76.0 km	May 9, 2008
6.7	43 km NW of Piti Village, Guam	130.0 km	Sep 17, 2014
6.5	276 km SW of Merizo Village, Guam	22.9 km	Oct 23, 1971

Significant earthquake record (42 events)

Every catalogued magnitude-6.0-and-above earthquake in Guam since 1900, most recent first.

Mag	Location	Depth	Date
6.0	191 km WSW of Merizo Village, Guam	65.0 km	Nov 4, 2025
6.0	168 km SSW of Merizo Village, Guam	15.0 km	Feb 13, 2022
6.7	43 km NW of Piti Village, Guam	130.0 km	Sep 17, 2014
6.3	272 km SSE of Inarajan Village, Guam	13.0 km	Jul 10, 2010
6.8	181 km WSW of Merizo Village, Guam	76.0 km	May 9, 2008
6.3	63 km NNW of Yigo Village, Guam	158.7 km	Feb 2, 2005
7.1	20 km SSW of Merizo Village, Guam	85.7 km	Apr 26, 2002
7.0	69 km SSE of Inarajan Village, Guam	37.0 km	Oct 12, 2001
6.2	166 km S of Merizo Village, Guam	33.0 km	Dec 19, 2000
6.2	30 km NNW of Yigo Village, Guam	132.2 km	Feb 26, 2000
6.0	45 km SSW of Merizo Village, Guam	50.9 km	Dec 19, 1999
6.0	229 km SW of Merizo Village, Guam	9.2 km	Sep 22, 1998
6.0	71 km N of Yigo Village, Guam	154.1 km	May 15, 1998
6.0	8 km SSE of Merizo Village, Guam	29.0 km	May 9, 1997
6.5	49 km N of Yigo Village, Guam	100.8 km	Apr 23, 1997
6.0	41 km SE of Inarajan Village, Guam	18.3 km	Aug 16, 1993
6.2	91 km ESE of Yigo Village, Guam	21.6 km	Aug 11, 1993
7.8	32 km S of Inarajan Village, Guam	59.3 km	Aug 8, 1993
6.0	54 km NNW of Yigo Village, Guam	155.7 km	Feb 10, 1991
6.0	120 km SSW of Merizo Village, Guam	31.9 km	May 31, 1985
6.1	61 km ENE of Yigo Village, Guam	98.0 km	Sep 22, 1984
6.1	235 km SW of Merizo Village, Guam	33.0 km	Sep 17, 1977
6.1	36 km NNW of Yigo Village, Guam	113.0 km	Nov 1, 1975
6.2	294 km WSW of Merizo Village, Guam	20.0 km	Oct 24, 1971
6.5	293 km WSW of Merizo Village, Guam	15.0 km	Oct 24, 1971
6.5	276 km SW of Merizo Village, Guam	22.9 km	Oct 23, 1971
6.0	20 km SW of Merizo Village, Guam	30.0 km	Sep 16, 1970
6.2	148 km SW of Merizo Village, Guam	17.9 km	Mar 4, 1970
6.0	134 km E of Yigo Village, Guam	15.0 km	Jan 13, 1959
6.2	283 km SW of Merizo Village, Guam	15.0 km	Aug 2, 1950
6.2	121 km SSW of Merizo Village, Guam	25.0 km	Jun 12, 1946
6.0	70 km SE of Inarajan Village, Guam	35.0 km	Jan 30, 1937
6.2	40 km E of Yigo Village, Guam	35.0 km	Dec 13, 1936
6.4	46 km ENE of Yigo Village, Guam	70.0 km	Oct 29, 1936
6.2	254 km S of Merizo Village, Guam	15.0 km	Mar 15, 1932
7.2	265 km S of Merizo Village, Guam	15.0 km	Jan 28, 1931
6.0	206 km SW of Merizo Village, Guam	20.0 km	May 1, 1929
6.3	146 km WSW of Merizo Village, Guam	15.0 km	Nov 24, 1917
7.1	261 km S of Merizo Village, Guam	15.0 km	May 9, 1917
6.4	279 km S of Merizo Village, Guam	15.0 km	May 6, 1917
7.0	32 km NNE of Yigo Village, Guam	180.0 km	Oct 26, 1912
7.0	98 km SSE of Inarajan Village, Guam	15.0 km	Dec 9, 1909

Peak-magnitude sample from the same roster

A Guam-keyed shuffle of states with a recorded max magnitude. Layout order flips by state so sibling pages do not open the same block first.

Northern Mariana Islands

3,345 M4+ events

M7.7

Arizona

7 M4+ events

M5.3

Arkansas

5 M4+ events

M4.7

Michigan

1 M4+ events

M4.2

California

885 M4+ events

M7.2

Missouri

2 M4+ events

M4.0

Other states in this catalog sample

A second Guam-keyed shuffle of the full 38-state roster (not ABS-gap nearest neighbors).

Utah

25 M4+ events · strongest M5.7

M5.7

Northern Mariana Islands

3,345 M4+ events · strongest M7.7

M7.7

Maryland

1 M4+ events · strongest M4.6

M4.6

U.S. Virgin Islands

222 M4+ events · strongest M6.1

M6.1

Louisiana

5 M4+ events · strongest M5.3

M5.3

Maine

1 M4+ events · strongest M4.7

M4.7

According to the US Geological Survey Earthquake Hazards Program, PlainQuake's figures are rendered directly from 317,293 recorded M4+ earthquakes and 14,444 significant M6+ events (USGS ComCat, 2005-present) -- no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 2026-08-26.