QuakeScout
Magnitude4.0

Reviewed by USGSAlaska33y ago

M4.0 earthquake 87 km SE of Sand Point, Alaska

Wednesday, July 14, 1993, 05:24:39 UTC · 54.704°N, 159.684°W

A magnitude 4.0 earthquake struck 87 km SE of Sand Point, Alaska on Wednesday, July 14, 1993, 05:24:39 UTC, at a depth of 33.0 km (shallow).

Magnitude
4.0
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

15 tons of TNT

That is about 1/998 of the Hiroshima bomb. A magnitude 5.0 releases about 32 times more energy.

Tectonic setting

96 km

from the nearest mapped plate boundary, between the North American 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 1 M2.5+ earthquake within 50 km in the following 30 days; the largest was M4.4 on July 17, 1993. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

M3M41h6h1d3d7d14d30dMainshock M4.0
Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.
  1. 4.486 km SE of Sand Point, Alaska33y ago · 7 km NE of this epicenter

Regional history

Past M5+ earthquakes within 300 km

USGS lists 197 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

  1. 8.6The 1946 Unimak Island, Alaska EarthquakeApril 1, 1946 · 246 km SW of this epicenter
  2. 8.21938 Semidi Islands, Alaska EarthquakeNovember 10, 1938 · 110 km NE of this epicenter
  3. 7.454 km SE of Sand Point, AlaskaMay 31, 1917 · 35 km N of this epicenter
  4. 7.190 km SE of King Cove, AlaskaMay 14, 1948 · 96 km W of this epicenter
  5. 7.0113 km ESE of Chignik, AlaskaMay 4, 1923 · 224 km NE of this epicenter
  6. 7.071 km SE of King Cove, AlaskaMay 30, 1991 · 125 km W of this epicenter
  7. 7.0164 km SE of Chignik, AlaskaSeptember 4, 1989 · 219 km E of this epicenter
  8. 6.9105 km ESE of Perryville, AlaskaNovember 17, 1938 · 147 km NE of this epicenter

History · NOAA

Deadliest earthquakes in this area

NOAA’s significant-earthquake database lists 7 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 168 recorded deaths. The most severe:

  1. 1946M8.6

    Unimak Island

    1 Apr 1946 · 246 km away · intensity VI

    168 deaths$26 million damagetsunami

  2. 1938M8.2

    Alaska

    10 Nov 1938 · 120 km away · intensity VI

    tsunami

  3. 1788M8.0

    Alaska Peninsula

    6 Aug 1788 · 90 km away

    tsunami

  4. 1948M7.5

    Alaska Peninsula

    14 May 1948 · 88 km away

  5. 1989M6.9

    Alaska

    4 Sep 1989 · 204 km away

    tsunami

  6. 1868

    Alaska Peninsula

    15 May 1868 · 90 km away

    tsunami

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

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