M5.6 earthquake 4 km E of Scotts Mills, Oregon

Thursday, March 25, 1993, 13:34:35 UTC · 45.035°N, 122.606°W

A magnitude 5.6 earthquake struck 4 km E of Scotts Mills, Oregon on Thursday, March 25, 1993, 13:34:35 UTC, at a depth of 19.6 km (shallow). It is the strongest earthquake within 300 km since an M5.7 on May 18, 1980.

Magnitude: 5.6; Moderate · md
Depth: 20 km; Shallow
Felt reports: 0; Did You Feel It?
Est. shaking: VI; Strong (ShakeMap)
PAGER alert: None; Not issued
Tsunami: No flag; USGS feed

Outlined circle: this earthquakeDashed circle: 75 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)

In context

How big was it, and why here?

Energy released

4 kilotons of TNT

That is about 1/4 of the Hiroshima bomb. It released about 8 times the energy of a magnitude 5.0.

Tectonic setting

222 km

from the nearest mapped plate boundary, between the Juan de Fuca and North American plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.

Depth: shallow

20 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 8 M2.5+ earthquakes within 75 km in the following 30 days; the largest was M3.2 on March 25, 1993. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.

Regional history

Past M5+ earthquakes within 300 km

USGS lists 27 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

History · NOAA

Deadliest earthquakes in this area

NOAA’s significant-earthquake database lists 5 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 76 recorded deaths. The most severe:

1980M5.2
Mt St Helens
18 May 1980 · 135 km away · intensity V
61 deaths$2.0 billion damagetsunami
1949M7.0
Washington
13 Apr 1949 · 237 km away · intensity VIII
8 deaths$25 million damagetsunami
1965M6.6
Seattle
29 Apr 1965 · 264 km away · intensity VIII
7 deaths$28 million damage
1993M5.6
Washington-Oregon Border
25 Mar 1993 · 0 km away · intensity VII
$28 million damage
1700M9.0
Cascadia Subduction Zone
27 Jan 1700 · 188 km away
Severe damage ($5–24M)tsunami

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

Nearby trackers