QuakeScout
Magnitude5.1

Reviewed by USGSNorthern Mariana Islands36y ago

M5.1 earthquake 243 km ENE of Saipan, Northern Mariana Islands

Tuesday, July 3, 1990, 02:38:32 UTC · 15.678°N, 147.970°E

A magnitude 5.1 earthquake struck 243 km ENE of Saipan, Northern Mariana Islands on Tuesday, July 3, 1990, 02:38:32 UTC, at a depth of 22.3 km (shallow). It is the strongest earthquake within 300 km since an M5.3 on June 14, 1990.

Magnitude
5.1
Moderate · mb
Depth
22 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: 75 km aftershock search area

In context

How big was it, and why here?

Energy released

674 tons of TNT

That is about 1/22 of the Hiroshima bomb. It released about 1 times the energy of a magnitude 5.0.

Tectonic setting

30 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

22 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 75 km

USGS lists 5 M2.5+ earthquakes within 75 km in the following 30 days; the largest was M4.9 on July 4, 1990. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

M3M4M51h6h1d3d7d14d30dMainshock M5.1
Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.
  1. 4.8186 km E of Saipan, Northern Mariana Islands36y ago · 69 km SW of this epicenter
  2. 4.8248 km E of Saipan, Northern Mariana Islands36y ago · 9 km SE of this epicenter
  3. 4.5233 km E of Saipan, Northern Mariana Islands36y ago · 14 km SW of this epicenter
  4. 4.9230 km ENE of Saipan, Northern Mariana Islands36y ago · 13 km W of this epicenter
  5. 4.7265 km E of Saipan, Northern Mariana Islands36y ago · 27 km E of this epicenter

Regional history

Past M5+ earthquakes within 300 km

USGS lists 203 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

  1. 7.7Mariana Islands regionDecember 28, 1940 · 286 km N of this epicenter
  2. 7.6198 km E of Saipan, Northern Mariana IslandsApril 5, 1990 · 73 km SW of this epicenter
  3. 7.5Mariana Islands regionJanuary 17, 1940 · 163 km N of this epicenter
  4. 7.1233 km NE of Saipan, Northern Mariana IslandsJuly 2, 1949 · 109 km NW of this epicenter
  5. 7.0176 km ESE of San Jose Village, Northern Mariana IslandsMay 18, 1913 · 184 km SW of this epicenter
  6. 7.0233 km ESE of Saipan, Northern Mariana IslandsJune 14, 1942 · 118 km S of this epicenter
  7. 6.6Mariana Islands regionSeptember 1, 1970 · 229 km N of this epicenter
  8. 6.6Alamagan region, Northern Mariana IslandsFebruary 10, 1921 · 274 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:

  1. 1990M7.5

    Saipan; Guam

    5 Apr 1990 · 73 km away · intensity IV

    tsunami

NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.

Nearby trackers

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