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Seismic Event Dossier23:32 Local (03:32 UTC)(87y ago)

M 7.8 earthquake Chillán, Ñuble, Chile

A magnitude 7.8 (MW) earthquake occurred on 1939-01-25, 23:32 local time (03:32 UTC) (87y ago), centered 35 km N of Chillán (Chile). The hypocenter was located at a intermediate depth of 35 km. Primary telemetry verified by USGS.

Historical Landmark Earthquake

#32 of All Time

Curated Global Seismic Archive (1700–Present)

Top-100 Earthquakes

A magnitude 7.8 earthquake struck ⁨Chillán, Ñuble, Chile⁩ on January 25, 1939. Source: ⁨Peru–Chile Trench⁩. Documented deaths: 30,000.

Documented Fatalities30,000Source: NOAA NCEI Significant Earthquake Database
Fault KinematicsSubduction Megathrust
Equivalent Energy7.56 Mt TNT

Magnitude

MW
M 7.8

7.56 Mt TNT

Depth

35 km
35 km

intermediate (35–70 km (Intermediate))

PAGER Impact

orange
100 – 1,000 fatalities

Injuries: > 5,000 · ~20M felt

Interactive Epicenter & Fault Map

36.30°S, 72.21°W
Fault104 km
Peru–Chile Trench
Subduction Megathrust · ~15.0 mm/yr
Felt byMMI III+
~20M exposed
~2.8M strong shaking
Primary SolutionUSGS
USGS#iscgem901785reviewed
1 agencies reporting
Setting36.3°S
Central Chile (Santiago & Valparaíso)
Continental / Inland crustal

Seismic Activity & Aftershock Sequence

Timeline of foreshocks, main rupture, aftershocks and machine learning risk probability evolution.

M0.0M4.5M9.0100%50%0%MainshockJan 24, 04 PMJan 25, 04 AMJan 25, 04 PMJan 26, 04 AMJan 26, 04 PMJan 27, 04 AMJan 27, 04 PMJan 28, 04 AMM7.8
Hover or tap a point to inspect aftershocks and risk probability curve.
<35 km (Shallow)35–70 km (Intermediate)>70 km (Deep)Mainshock

Situation Monitoring

Continuous verification
Multi-agency verification of casualties, tsunami alerts, and seismic sequence

Key facts so far

Casualties
Damage assessment in progress
Tsunami Status
No tsunami threat
NOAA PTWC & regional buoys
Citizen Felt Reports
0
No felt reports submitted
Macroseismic DYFI verification
Aftershock Sequence
Monitoring
Aftershocks expected (Omori law)
LightGBM hazard model forecast
Multi-agency seismic telemetry active. Awaiting wire headlines.

Agency Discrepancy Matrix (Cross-Network Verification)

Comparing multi-network solutions from primary and teleseismic monitoring agencies.

Network / SourceMagnitude (Scale & Diff)Depth & DiffEpicenter & Shift (Δd)ConsensusEvent ID / Data
USGS
United States Geological Survey · Global / US
M7.8(Mw)Ref
35.0 kmRef
-36.30°, -72.21°Origin
Authoritative
iscgem901785

Why do agency magnitudes differ? Seismological agencies use different instrumentation networks, crustal velocity models, and mathematical magnitude scales (e.g. Moment Magnitude Mw vs Local Richter ML vs Surface Wave Ms). Differences of 0.1–0.3 are common and reflect physical observation geometry rather than errors.

Where it was felt

6 settlements

Shaking intensity is modelled from magnitude, depth and distance (GMPE attenuation), not reported by residents.

TownDistanceIntensity
Chillán · Ñuble35 kmMMI IX
Cauquenes · Maule39 kmMMI IX
Linares · Maule76 kmMMI VIII
Talcahuano · Bío-Bío93 kmMMI VIII
Concepción · Bío-Bío96 kmMMI VIII
Talca · Maule106 kmMMI VIII

Tectonic setting

Nearest mapped active fault: Peru–Chile Trench, 104 km away, slip rate ~15.0 mm/yr (GEM Global Active Faults).

Regional Seismic Profile

Central Chile (Santiago & Valparaíso)

View live seismic monitoring, historical danger benchmarks, fault slip models and recurrence intervals for this zone.