Reviewed by USGSNorthern Mariana Islands31y ago
M7.1 earthquake in Pagan region, Northern Mariana Islands
Wednesday, August 23, 1995, 07:06:02 UTC · 18.856°N, 145.218°E
A magnitude 7.1 earthquake struck in Pagan region, Northern Mariana Islands on Wednesday, August 23, 1995, 07:06:02 UTC, at a depth of 594.9 km (deep). It is the strongest earthquake within 300 km since an M7.7 on December 28, 1940.
- Magnitude
- 7.1
- Major · mwb
- Depth
- 595 km
- Deep
- 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: 200 km aftershock search area
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
66 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: deep
595 km
Deep earthquakes (over 300 km) happen deep inside subducting plates. They rarely cause damage, but can be felt faintly over very large distances.
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 18 M2.5+ earthquakes within 200 km in the following 30 days; the largest was M6.2 on August 24, 1995. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
- 4.1Pagan region, Northern Mariana Islands31y ago · 11 km W of this epicenter
- 4.3Pagan region, Northern Mariana Islands31y ago · 28 km SE of this epicenter
- 4.5Pagan region, Northern Mariana Islands31y ago · 28 km E of this epicenter
- 4.2Mariana Islands region31y ago · 190 km E of this epicenter
- 4.3Pagan region, Northern Mariana Islands31y ago · 12 km SW of this epicenter
- 5.4Pagan region, Northern Mariana Islands31y ago · 16 km S of this epicenter
- 3.4Pagan region, Northern Mariana Islands31y ago · 66 km SE of this epicenter
- 6.2Pagan region, Northern Mariana Islands31y ago · 14 km W of this epicenter
Regional history
Past M5+ earthquakes within 300 km
USGS lists 250 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.7Mariana Islands regionDecember 28, 1940 · 247 km E of this epicenter
- 7.2Pagan region, Northern Mariana IslandsOctober 24, 1930 · 161 km E of this epicenter
- 6.9Maug Islands region, Northern Mariana IslandsMarch 7, 1962 · 27 km N of this epicenter
- 6.7Pagan region, Northern Mariana IslandsNovember 15, 1954 · 60 km E of this epicenter
- 6.7Pagan region, Northern Mariana IslandsFebruary 1, 1956 · 23 km W of this epicenter
- 6.7Mariana Islands regionSeptember 16, 1986 · 128 km NE of this epicenter
- 6.6Maug Islands region, Northern Mariana IslandsSeptember 29, 1960 · 62 km NW of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 1 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1902M8.1
Agana
22 Sep 1902 · 126 km away · intensity IX
Severe damage ($5–24M)
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.