Reviewed by USGSNorthern Mariana Islands36y ago
M4.7 earthquake 221 km ENE of Saipan, Northern Mariana Islands
Saturday, May 12, 1990, 17:23:42 UTC · 15.619°N, 147.776°E
A magnitude 4.7 earthquake struck 221 km ENE of Saipan, Northern Mariana Islands on Saturday, May 12, 1990, 17:23:42 UTC, at a depth of 33.0 km (shallow). It is the strongest earthquake within 300 km since an M4.9 on May 11, 1990.
- Magnitude
- 4.7
- 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
169 tons of TNT
That is about 1/89 of the Hiroshima bomb. A magnitude 5.0 releases about 3 times more energy.
Tectonic setting
11 km
from the nearest mapped plate boundary, between the Mariana and Pacific 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 13 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M5.3 on May 27, 1990. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
- 4.8215 km E of Saipan, Northern Mariana Islands36y ago · 9 km SW of this epicenter
- 4.9207 km ENE of Saipan, Northern Mariana Islands36y ago · 15 km W of this epicenter
- 5.1216 km E of Saipan, Northern Mariana Islands36y ago · 9 km SW of this epicenter
- 4.7223 km E of Saipan, Northern Mariana Islands36y ago · 27 km S of this epicenter
- 4.5224 km E of Saipan, Northern Mariana Islands36y ago · 15 km S of this epicenter
- 4.6203 km E of Saipan, Northern Mariana Islands36y ago · 19 km W of this epicenter
- 5.3205 km E of Saipan, Northern Mariana Islands36y ago · 22 km SW of this epicenter
- 4.8206 km ENE of Saipan, Northern Mariana Islands36y ago · 17 km W of this epicenter
Regional history
Past M5+ earthquakes within 300 km
USGS lists 207 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 · 289 km N of this epicenter
- 7.6198 km E of Saipan, Northern Mariana IslandsApril 5, 1990 · 58 km S of this epicenter
- 7.5Mariana Islands regionJanuary 17, 1940 · 172 km N of this epicenter
- 7.1233 km NE of Saipan, Northern Mariana IslandsJuly 2, 1949 · 107 km N of this epicenter
- 7.0176 km ESE of San Jose Village, Northern Mariana IslandsMay 18, 1913 · 168 km SW of this epicenter
- 7.0233 km ESE of Saipan, Northern Mariana IslandsJune 14, 1942 · 110 km S of this epicenter
- 6.6Mariana Islands regionSeptember 1, 1970 · 234 km N of this epicenter
- 6.6Alamagan region, Northern Mariana IslandsFebruary 10, 1921 · 270 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:
- 1990M7.5
Saipan; Guam
5 Apr 1990 · 58 km away · intensity IV
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.