Reviewed by USGSNorthern Mariana Islands21y ago
M4.6 earthquake in Saipan region, Northern Mariana Islands
Friday, February 25, 2005, 08:20:43 UTC · 15.874°N, 145.018°E
A magnitude 4.6 earthquake struck in Saipan region, Northern Mariana Islands on Friday, February 25, 2005, 08:20:43 UTC, at a depth of 9.2 km (shallow). It is the strongest earthquake within 300 km since an M6.6 on February 5, 2005.
- Magnitude
- 4.6
- Light · mb
- Depth
- 9 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
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
24 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
9 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 M4.9 on February 25, 2005. 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 402 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.6198 km E of Saipan, Northern Mariana IslandsApril 5, 1990 · 289 km E of this epicenter
- 7.1233 km NE of Saipan, Northern Mariana IslandsJuly 2, 1949 · 271 km E of this epicenter
- 7.0176 km ESE of San Jose Village, Northern Mariana IslandsMay 18, 1913 · 286 km SE of this epicenter
- 7.032 km NNE of Yigo Village, GuamOctober 26, 1912 · 229 km S of this epicenter
- 6.689 km N of Saipan, Northern Mariana IslandsFebruary 5, 2005 · 92 km E of this epicenter
- 6.6Alamagan region, Northern Mariana IslandsFebruary 10, 1921 · 275 km NE of this epicenter
- 6.5258 km NE of Saipan, Northern Mariana IslandsDecember 1, 1938 · 271 km NE 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:
- 1902M8.1
Agana
22 Sep 1902 · 258 km away · intensity IX
Severe damage ($5–24M)
- 1849M7.5
Guam
25 Jan 1849 · 278 km away · intensity IX
Severe damage ($5–24M)tsunami
- 1892M7.5
Guam
16 May 1892 · 278 km away · intensity VIII
Moderate damage ($1–5M)tsunami
- 1825
Ladrones Island
Apr 1825 · 278 km away · intensity VIII
Moderate damage ($1–5M)tsunami
- 1834
Agana
May 1834 · 278 km away
Moderate damage ($1–5M)
- 1997M6.5
Guam
23 Apr 1997 · 210 km away · intensity VII
Limited damage (under $1M)
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.