Reviewed by USGSNorthern Mariana Islands37y ago
M7.6 earthquake 198 km E of Saipan, Northern Mariana Islands
Thursday, April 5, 1990, 21:12:35 UTC · 15.125°N, 147.596°E
A magnitude 7.6 earthquake struck 198 km E of Saipan, Northern Mariana Islands on Thursday, April 5, 1990, 21:12:35 UTC, at a depth of 11.4 km (shallow). No earthquake of this size or larger appears within 300 km in the USGS catalog since 1900.
- Magnitude
- 7.6
- Major · mw
- Depth
- 11 km
- Shallow
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- V
- Moderate (ShakeMap)
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeDashed circle: 200 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)
In context
How big was it, and why here?
Energy released
3.8 megatons of TNT
That is about 252 times the Hiroshima bomb. It released about 7,943 times the energy of a magnitude 5.0.
Tectonic setting
9 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
11 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 200 km
USGS lists 139 M2.5+ earthquakes within 200 km in the following 30 days; the largest was M6.3 on April 6, 1990. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
- 3.6229 km E of Saipan, Northern Mariana Islands36y ago · 61 km NE of this epicenter
- 4.8195 km ENE of Saipan, Northern Mariana Islands36y ago · 97 km N of this epicenter
- 4.5Mariana Islands region36y ago · 144 km E of this epicenter
- 4.7190 km E of Saipan, Northern Mariana Islands36y ago · 11 km NW of this epicenter
- 4.5Mariana Islands region36y ago · 83 km NE of this epicenter
- 4.7194 km E of Saipan, Northern Mariana Islands36y ago · 7 km NW of this epicenter
- 4.5199 km E of Saipan, Northern Mariana Islands36y ago · 9 km N of this epicenter
- 4.6193 km E of Saipan, Northern Mariana Islands36y ago · 8 km SW of this epicenter
Regional history
Past M5+ earthquakes within 300 km
USGS lists 164 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.5Mariana Islands regionJanuary 17, 1940 · 229 km N of this epicenter
- 7.1233 km NE of Saipan, Northern Mariana IslandsJuly 2, 1949 · 157 km N of this epicenter
- 7.0176 km ESE of San Jose Village, Northern Mariana IslandsMay 18, 1913 · 111 km SW of this epicenter
- 7.0233 km ESE of Saipan, Northern Mariana IslandsJune 14, 1942 · 61 km SE of this epicenter
- 6.6Mariana Islands regionSeptember 1, 1970 · 289 km N of this epicenter
- 6.5258 km NE of Saipan, Northern Mariana IslandsDecember 1, 1938 · 217 km N of this epicenter
- 6.446 km ENE of Yigo Village, GuamOctober 29, 1936 · 295 km SW of this epicenter
- 6.3215 km ENE of Saipan, Northern Mariana IslandsMarch 19, 1932 · 107 km N 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 · 0 km away · intensity IV
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.