Reviewed by USGSGuam25y ago
M4.5 earthquake 213 km SW of Merizo Village, Guam
Sunday, October 21, 2001, 01:42:29 UTC · 11.902°N, 143.282°E
A magnitude 4.5 earthquake struck 213 km SW of Merizo Village, Guam on Sunday, October 21, 2001, 01:42:29 UTC, at a depth of 33.0 km (shallow). It is the strongest earthquake within 300 km since an M5.2 on October 14, 2001.
- Magnitude
- 4.5
- Light · mb
- Depth
- 33 km
- Shallow
- Felt reports
- 0
- Did You Feel It?
- 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
85 tons of TNT
That is about 1/178 of the Hiroshima bomb. A magnitude 5.0 releases about 6 times more energy.
Tectonic setting
20 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: shallow
33 km
Shallow earthquakes (under 70 km) produce the strongest surface shaking for their size, so they are the ones most likely to cause damage near the epicenter.
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 50 km
USGS lists 1 M2.5+ earthquake within 50 km in the following 30 days; the largest was M4.8 on November 9, 2001. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 463 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.832 km S of Inarajan Village, GuamAugust 8, 1993 · 204 km NE of this epicenter
- 7.2265 km S of Merizo Village, GuamJanuary 28, 1931 · 172 km SE of this epicenter
- 7.1261 km S of Merizo Village, GuamMay 9, 1917 · 165 km SE of this epicenter
- 7.098 km SSE of Inarajan Village, GuamDecember 9, 1909 · 190 km E of this epicenter
- 7.032 km NNE of Yigo Village, GuamOctober 26, 1912 · 280 km NE of this epicenter
- 7.069 km SSE of Inarajan Village, GuamOctober 12, 2001 · 204 km NE of this epicenter
- 6.7Mariana Islands regionOctober 18, 1935 · 213 km W of this epicenter
- 6.5276 km SW of Merizo Village, GuamOctober 23, 1971 · 79 km W of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 11 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 · 204 km away · intensity IX
$250 million damagetsunami
- 1849M7.5
Guam
25 Jan 1849 · 233 km away · intensity IX
Severe damage ($5–24M)tsunami
- 1909M8.0
Guam
9 Dec 1909 · 198 km away · intensity VIII
Moderate damage ($1–5M)tsunami
- 1892M7.5
Guam
16 May 1892 · 233 km away · intensity VIII
Moderate damage ($1–5M)tsunami
- 2001M7.0
Guam
12 Oct 2001 · 204 km away · intensity VIII
Moderate damage ($1–5M)
- 1825
Ladrones Island
Apr 1825 · 233 km away · intensity VIII
Moderate damage ($1–5M)tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.