October 4, 1983 Earthquake: Copoapo-Chanaral, Northern, Chile

Name: October 4, 1983 Earthquake: Copoapo-Chanaral, Northern, Chile
Start: 1983-10-04
Location: Copoapo-Chanaral, Northern, Chile

October 4, 1983 · M7.3 · 5 deaths · $1 million · 40 houses destroyed

A magnitude 7.3 earthquake struck Copoapo-Chanaral, Northern, Chile on October 4, 1983 at 18:52:13 UTC, 15 km below the surface. It killed 5 people.

Map

Where it struck, with the other significant earthquakes within 200 km. Circles are sized and colored by magnitude; select one for its page.

The earthquake

Date: October 4, 1983
Time: 18:52:13 UTC
Place: Copoapo-Chanaral, Northern, Chile
Magnitude: 7.3 (Ms)
Magnitude scales: Ms 7.3 · mb 6.4
Focal depth: 15 km (9 mi)
Intensity: VII, very strong shaking, on the Modified Mercalli scale
Tsunami: Yes: the tsunami it caused
Epicenter: 26.535° S, 70.563° W
Country: Chile
Region: South America
USGS record: The USGS’s page for this earthquake

Ms: surface-wave magnitude. mb: body-wave (P-wave) magnitude. NCEI’s headline magnitude is the best of these for the earthquake.

The toll

Deaths: 5
Injuries: 12
Damage: $1 million
Houses destroyed: 40

Where the literature gives no number, NCEI records a description on a scale of 1 to 4, printed here in its words. Damage is in millions of US dollars of the year of the event, not adjusted for inflation.

What happened

The USGS’s account of the effects of this earthquake.

At least 5 people were killed, 24 injured and extensive damage in the Copiapo-Chanaral area. A 1.5 meter uplift near Chanaral was reported and some roads were blocked by landslides. A minor tsunami was recorded at Valparaiso. Felt strongly (VII) in northern Chile. Felt also in Argentina, Bolivia and Brazil. This appears to be a multiple event. Note the difference in waveforms on focal sphere solutions between this event and the event of October 9 at 112540.58. [FS]. FAULT PLANE SOLUTION: P-WAVES NP1:STRIKE=160;DIP=74;SLIP=90 NP2:STRIKE=340;DIP=16;SLIP=90 PRINCIPAL AXES: (T) PLG=61; AZM=70 (P) PLG=29; AZM=250 COMMENT: The focal mechanism is poorly controlled and corresponds to reverse faulting. The preferred fault plane is NP2. MOMENT TENSOR SOLUTION NO OF STA 16 SCALE 10**27 D-CM DEPTH 50 PRINCIPAL AXES: (T) VAL=1.60; PLG=58; AZM=48 (N) VAL=0.02; PLG=30; AZM=207 (P) VAL=-1.62; PLG=9; AZM=302 BEST DOUBLE COUPLE:Mo=1.6*10**27 NP1:STRIKE=63;DIP=44;SLIP=136 NP2:STRIKE=188;DIP=61;SLIP=55 COMMENT: Complex event. CENTROID, MOMENT TENSOR SOLUTION HARVARD EVENT-FILE NAME C100483C DATA USED: GDSN L.P. BODY WAVES: 17S, 48C, T=45 MANTLE WAVES: 21S, 57C, T=135 CENTROID LOCATION: ORIGIN TIME 18:52:37.8 0.2 LAT 26.01S 0.02;LON 70.56W 0.02 DEP 38.7 1.0;HALF-DURATION 29.0 MOMENT TENSOR; SCALE 10**27 D-CM MRR=2.04 0.04; MTT=0.13 0.02 MFF=-2.18 0.02; MRT=0.68 0.11 MRF=-2.55 0.15; MTF=0.08 0.02 PRINCIPAL AXES: 1.(T) VAL=3.35;PLG=63;AZM=66 2.(N) 0.06; 7; 170 3.(P) -3.41; 26; 263 BEST DOUBLE COUPLE:M0=3.4*10**27 NP1:STRIKE=9;DIP=20;SLIP=110 NP2:Strike=168;Dip=71;Slip=83

From the USGS event page for usp0001ytj. U.S. Geological Survey text and figures are in the public domain.

Magnitude estimates

The magnitudes the USGS catalog lists for this earthquake, by scale and by who computed them. NCEI’s own scales are in the table above.

Mag.	Scale	Computed by	Notes
7.4	Mw, moment	USGS National Earthquake Information Center	Preferred · Reviewed
7.62	Mw, moment	ISC-GEM global catalog	Final · ±0.1
7.6	Mwc, centroid moment	Global CMT project	Preliminary

What the record says

NCEI’s account, from the sources it cites.

On October 4, 1983, at 18;52 UTC, a strong earthquake, measuring 7.4 (Richter) jolted northern Chile. The quake was located near 25.9 S and 70 W, south of Antofagasta. Five people were killed and at last 12 people reported injured. About 40 homes were either destroyed or damaged. The quake was felt as far away as Sao Paulo, Brazil and caused buildings to sway. A 150 cm drop in sea level was reported at Chanaral, Chile, near the epienter. This might have been caused by the uplift of the land. (reference #3332)

Sources NCEI cites

The publications NCEI lists for this record. The numbers match the “reference #” notes in its account above.

#1250 Centre for Research on the Epidemiology of Disasters (CRED) and the U.S. Office of Foreign Disaster Assistance (OFDA) (2001). EM-DAT: The OFDA/CRED International Disaster Database, Universite Catholique de Louvain, Brussels, Belgium, link
#3332 International Tsunami Information Center (1983). Tsunami Newsletter, Vol. XVI, No. 2, December 1983.
#1053 National Earthquake Information Center (NEIC) (1971 to 2013). Preliminary Determination of Epicenters (PDE), a weekly and monthly publication, National Earthquake Information Center, U.S. Geological Survey, Golden, Colorado, 1971 to 2013.
#1054 McClelland, Lindsay, et al, editors (1980-1989). SEAN Bulletin, a monthly publication of the Scientific Event Alert Network of the Smithsonian Institution, Washington, D.C.
#1066 Mengin, O., editor (1980 to Present). UNDRO News, a bimonthly publication of the United Nations Disaster Relief Organization Coordinator, Geneva, Switzerland, 1980 to present.
#1232 International Seismological Centre (1964-1990). Regional Catalogue of Earthquakes, 1964-1990, Edinburgh, Scotland.

Other significant earthquakes nearby

Within 200 km, the deadliest first.

Significant earthquakes of 1983 The 1900s Every quake the USGS located in 1983 Recent earthquakes near here This day in weather history

Sources

Significant earthquakes from NOAA’s National Centers for Environmental Information, Global Historical Hazard Database, cited as NCEI/WDS, doi:10.7289/V5PN93H7. Public domain. Read 2026-10-01. NCEI earthquake 4991. The written accounts and the magnitude estimates are from the USGS earthquake catalog, event usp0001ytj, matched to this record by time, place and magnitude.