Reviewed by USGSNorthern Mariana Islands66y ago
M6.6 earthquake in Maug Islands region, Northern Mariana Islands
Thursday, September 29, 1960, 11:18:55 UTC · 19.316°N, 144.888°E
A magnitude 6.6 earthquake struck in Maug Islands region, Northern Mariana Islands on Thursday, September 29, 1960, 11:18:55 UTC, at a depth of 419.5 km (deep). It is the strongest earthquake within 300 km since an M6.7 on February 1, 1956.
- Magnitude
- 6.6
- Strong · mw
- Depth
- 420 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 earthquake
In context
How big was it, and why here?
Energy released
133 kilotons of TNT
That is about 9 times the Hiroshima bomb. It released about 279 times the energy of a magnitude 5.0.
Tectonic setting
43 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
420 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 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 25 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 · 298 km SE of this epicenter
- 7.2Mariana Islands regionJuly 11, 1905 · 271 km N of this epicenter
- 7.2Pagan region, Northern Mariana IslandsOctober 24, 1930 · 213 km SE of this epicenter
- 7.2Mariana Islands regionJune 19, 1947 · 258 km N of this epicenter
- 7.0Mariana Islands regionJune 13, 1947 · 280 km N of this epicenter
- 6.7Pagan region, Northern Mariana IslandsNovember 15, 1954 · 102 km SE of this epicenter
- 6.7Pagan region, Northern Mariana IslandsFebruary 1, 1956 · 59 km S 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 · 187 km away · intensity IX
Severe damage ($5–24M)
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.