July 12, 1983 Earthquake: Prince William Sound, Alaska, United States
A magnitude 6.1 earthquake struck Prince William Sound, Alaska, United States on July 12, 1983 at 15:10:03 UTC, 37 km below the surface.
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
- July 12, 1983
- Time
- 15:10:03 UTC
- Place
- Prince William Sound, Alaska, United States
- Magnitude
- 6.1 (Ms)
- Magnitude scales
- Ms 6.1 · mb 6.1
- Focal depth
- 37 km (23 mi)
- Intensity
- VI, strong shaking, on the Modified Mercalli scale
- Tsunami
- None recorded
- Epicenter
- 61.031° N, 147.286° W
- Country
- United States
- Region
- North America and Hawaii
- 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
- Damage
- $1 million
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.
Damage (VI) at Valdez. Felt (V) at Chitina, Chugiak, Cooper Landing, Copper Center, Cordova, Fort Richardson, Gakona, Girdwood, Moose Pass, Skwentna, Sutton, Whittier and Willow. Felt (IV) at Anchorage, Palmer and Seward. Felt (III) at Fairbanks and Yakutat. Also felt (III) at Whitehorse, Yukon Territory. [FS]. FAULT PLANE SOLUTION: P-WAVES NP1:STRIKE=233;DIP=65;SLIP=-70 NP2:STRIKE=12;DIP=32;SLIP=-126 PRINCIPAL AXES: (T) PLG=18; AZM=308 (P) PLG=64; AZM=177 COMMENT: Poorly controlled normal fault type mechanism with a fair amount of left-lateral strike-slip component. NP1 designated as the fault plane. MOMENT TENSOR SOLUTION NO OF STA 14 SCALE 10**25 D-CM DEPTH 35 PRINCIPAL AXES: (T) VAL=7.66; PLG=23; AZM=319 (N) VAL=0.17; PLG=25; AZM=61 (P) VAL=-7.83; PLG=54; AZM=192 BEST DOUBLE COUPLE:Mo=7.7*10**25 NP1:STRIKE=9;DIP=31;SLIP=-146 NP2:STRIKE=249;DIP=73;SLIP=-63 CENTROID, MOMENT TENSOR SOLUTION HARVARD EVENT-FILE NAME C071283C DATA USED: GDSN L.P. BODY WAVES: 24S, 62C, T=45 MANTLE WAVES: 11S, 29C, T=135 CENTROID LOCATION: ORIGIN TIME 15:10: 9.3 0.2 LAT 61.15N 0.03;LON 147.19W 0.03 DEP 40.6 1.0;HALF-DURATION 7.0 MOMENT TENSOR; SCALE 10**25 D-CM MRR=-4.81 0.09; MTT=1.34 0.08 MFF=3.47 0.07; MRT=3.29 0.19 MRF=0.87 0.16; MTF=2.04 0.04 PRINCIPAL AXES: 1.(T) VAL=5.36;PLG=15;AZM=308 2.(N) 0.88; 18; 43 3.(P) -6.24; 66; 180 BEST DOUBLE COUPLE:M0=5.8*10**25 NP1:STRIKE=14;DIP=34;SLIP=-123 NP2:Strike=233;Dip=62;Slip=-70
Maximum observed Modified Mercalli Intensity (MMI) VI
From the USGS event page for usp0001wrg. 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 |
|---|---|---|---|
| 6.6 | Mw, moment | USGS National Earthquake Information Center | Preferred · Reviewed |
| 6.44 | Mw, moment | ISC-GEM global catalog | Final · ±0.1 |
| 6.47 | Mw, moment | USGS historic United States catalog | Final |
| 6.4 | Mwc, centroid moment | Global CMT project | Preliminary |
Sources NCEI cites
The publications NCEI lists for this record. The numbers match the “reference #” notes in its account above.
- #45 U.S. Department of the Interior, Geological Survey and U.S. Department of Commerce, National Oceanic and Atmospheric Administration (1928-1986). United States Earthquakes, Annual publication, published 1928-1986. vol.s for 1928-1965 issued by the U.S. Coast and Geodetic Survey; volumes for 1966-1969 issued by the National Earthquake Information Center; volume for 1970 issued by the National Geophysical Data Center; volumes for 1971-1972 issued by the National Geophysical And Solar-Terrestrial Data Center; volumes for 1973-1980 published jointly by the National Oceanic and Atmospheric Administration (NOAA) and the U.S. Geological Survey; volumes for 1981-1986 published by the U.S. Geological Survey. [on shelf]
- #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.
Other significant earthquakes nearby
Within 200 km, the deadliest first.
More
Significant earthquakes of 1983The 1900sEvery quake the USGS located in 1983Recent earthquakes near hereThis 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 4982. The written accounts and the magnitude estimates are from the USGS earthquake catalog, event usp0001wrg, matched to this record by time, place and magnitude.