QuakeScout
Magnitude3.5

Reviewed by USGSCalifornia42y ago

M3.5 earthquake 238 km WSW of Ferndale, California

Monday, October 15, 1984, 04:38:50 UTC · 40.129°N, 127.005°W

A magnitude 3.5 earthquake struck 238 km WSW of Ferndale, California on Monday, October 15, 1984, 04:38:50 UTC, at a depth of 4.1 km (shallow).

Magnitude
3.5
Minor · md
Depth
4 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 earthquake

In context

How big was it, and why here?

Energy released

3 tons of TNT

That is about 1/4,724 of the Hiroshima bomb. A magnitude 5.0 releases about 150 times more energy.

Tectonic setting

33 km

from the nearest mapped plate boundary, between the Pacific and Juan de Fuca plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.

Depth: shallow

4 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 has not published any M2.5+ earthquake within 50 km in the 30 days after this event.

Regional history

Past M5+ earthquakes within 300 km

USGS lists 135 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

  1. 7.4123 km W of Big Lagoon, CaliforniaJanuary 31, 1922 · 167 km NE of this epicenter
  2. 7.2The 1980 Eureka, California EarthquakeNovember 8, 1980 · 257 km NE of this epicenter
  3. 7.1The 1923 Humboldt County, California EarthquakeJanuary 22, 1923 · 172 km E of this epicenter
  4. 6.8123 km W of Ferndale, CaliforniaNovember 25, 1954 · 115 km E of this epicenter
  5. 6.884 km W of Ferndale, CaliforniaFebruary 9, 1941 · 159 km E of this epicenter
  6. 6.8off the coast of Northern CaliforniaJuly 6, 1934 · 165 km NE of this epicenter
  7. 6.7217 km W of Ferndale, CaliforniaSeptember 10, 1984 · 44 km N of this epicenter
  8. 6.552 km WNW of Big Lagoon, CaliforniaJuly 15, 1918 · 234 km NE of this epicenter

History · NOAA

Deadliest earthquakes in this area

NOAA’s significant-earthquake database lists 10 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 2 recorded deaths. The most severe:

  1. 1954M6.6

    Humboldt County

    21 Dec 1954 · 275 km away

    1 death$2 million damage

  2. 1932M6.5

    Eureka

    6 Jun 1932 · 240 km away · intensity VIII

    1 deathModerate damage ($1–5M)

  3. 1980M7.2

    North Coast

    8 Nov 1980 · 257 km away · intensity VII

    $2 million damage

  4. 1865

    Fort Humboldt, Eureka

    1 Oct 1865 · 233 km away · intensity IX

    Moderate damage ($1–5M)

  5. 1922M7.6

    Northern

    31 Jan 1922 · 160 km away

    Limited damage (under $1M)

  6. 1923M7.1

    Northern

    22 Jan 1923 · 172 km away · intensity VIII

    Limited damage (under $1M)tsunami

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

Nearby trackers

Closest city pages