QuakeScout
Magnitude4.3

Reviewed by USGSChile43y ago

M4.3 earthquake 126 km WNW of Copiapó, Chile

Friday, October 7, 1983, 02:39:38 UTC · 26.837°S, 71.462°W

A magnitude 4.3 earthquake struck 126 km WNW of Copiapó, Chile on Friday, October 7, 1983, 02:39:38 UTC, at a depth of 33.0 km (shallow).

Magnitude
4.3
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

43 tons of TNT

That is about 1/354 of the Hiroshima bomb. A magnitude 5.0 releases about 11 times more energy.

Tectonic setting

31 km

from the nearest mapped plate boundary, between the Nazca and South American 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 M5.0 on October 14, 1983. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

M3M4M51h6h1d3d7d14d30dMainshock M4.3
Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.
  1. 5.096 km NW of Copiapó, Chile43y ago · 33 km E of this epicenter

Regional history

Past M5+ earthquakes within 300 km

USGS lists 182 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

  1. 8.594 km ENE of Vallenar, ChileNovember 11, 1922 · 227 km SE of this epicenter
  2. 8.060 km W of Diego de Almagro, ChileDecember 4, 1918 · 91 km NE of this epicenter
  3. 7.79 km SSW of Taltal, ChileDecember 28, 1966 · 177 km NE of this epicenter
  4. 7.583 km NNE of Taltal, ChileJuly 13, 1936 · 270 km NE of this epicenter
  5. 7.550 km WNW of Diego de Almagro, ChileJune 8, 1909 · 122 km NE of this epicenter
  6. 7.4Atacama, ChileApril 18, 1939 · 72 km SE of this epicenter
  7. 7.454 km WSW of Diego de Almagro, ChileOctober 4, 1983 · 95 km E of this epicenter
  8. 7.377 km NNE of Taltal, ChileDecember 2, 1960 · 262 km NE of this epicenter

History · NOAA

Deadliest earthquakes in this area

NOAA’s significant-earthquake database lists 29 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 722 recorded deaths. The most severe:

  1. 1922M8.5

    Atacama

    11 Nov 1922 · 227 km away · intensity XI

    700 deathsSevere damage ($5–24M)tsunami

  2. 1859M7.6

    Chile

    5 Oct 1859 · 124 km away · intensity X

    10 deathsUnder $1 million damagetsunami

  3. 1983M7.3

    Northern: Copoapo-Chanaral

    4 Oct 1983 · 95 km away · intensity VII

    5 deaths$1 million damagetsunami

  4. 1966M7.8

    Taltal, Catalina

    28 Dec 1966 · 167 km away · intensity VIII

    3 deathsUnder $1 million damagetsunami

  5. 1946M7.9

    Northern

    2 Aug 1946 · 103 km away

    2 deathsSevere damage ($5–24M)tsunami

  6. 1936M7.3

    Taltal

    13 Jul 1936 · 298 km away

    1 deathModerate damage ($1–5M)tsunami

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

Nearby trackers

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