Reviewed by USGSNorthern Mariana Islands86y ago
M6.3 earthquake in Pagan region, Northern Mariana Islands
Saturday, August 30, 1941, 13:07:00 UTC · 18.080°N, 146.425°E
A magnitude 6.3 earthquake struck in Pagan region, Northern Mariana Islands on Saturday, August 30, 1941, 13:07:00 UTC, at a depth of 35.0 km (shallow). It is the strongest earthquake within 300 km since an M6.3 on August 30, 1941.
- Magnitude
- 6.3
- Strong · mw
- Depth
- 35 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 earthquake
In context
How big was it, and why here?
Energy released
38 kilotons of TNT
That is about 3 times the Hiroshima bomb. It released about 80 times the energy of a magnitude 5.0.
Tectonic setting
147 km
from the nearest mapped plate boundary, between the Mariana and Pacific plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.
Depth: shallow
35 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 100 km
USGS has not published any M2.5+ earthquake within 100 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 13 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 · 110 km E of this epicenter
- 7.5Mariana Islands regionJanuary 17, 1940 · 202 km SE of this epicenter
- 7.2Pagan region, Northern Mariana IslandsOctober 24, 1930 · 49 km NE of this epicenter
- 6.6Alamagan region, Northern Mariana IslandsFebruary 10, 1921 · 40 km SE of this epicenter
- 6.5258 km NE of Saipan, Northern Mariana IslandsDecember 1, 1938 · 144 km SE of this epicenter
- 6.5Pagan region, Northern Mariana IslandsOctober 28, 1930 · 53 km NE of this epicenter
- 6.3Mariana Islands regionAugust 30, 1941 · 73 km NE 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 · 46 km away · intensity IX
Severe damage ($5–24M)
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.