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Seismic Event Dossier00:11 Local (16:11 UTC)(50y ago)

M 7.9 earthquake Shariff Kabunsuan, Philippines

A magnitude 7.9 (MW) earthquake occurred on 1976-08-16, 00:11 local time (16:11 UTC) (50y ago), centered 109 km S of Cotabato (Philippines). The hypocenter was located at a shallow depth of 33 km. Primary telemetry verified by USGS.

Historical Landmark Earthquake

#29 of All Time

Curated Global Seismic Archive (1700–Present)

Top-100 Earthquakes

A magnitude 7.9 earthquake struck ⁨Shariff Kabunsuan, Philippines⁩ on 16 agosto 1976. Source: ⁨Cotabato Trench⁩. Documented deaths: 8,000.

Documented Fatalities8,000Source: NOAA NCEI Significant Earthquake Database
Fault KinematicsSubduction Megathrust
Equivalent Energy10.68 Mt TNT

Magnitudo

MW
M 7.9

10.68 Mt TNT

Profondità

33 km
33 km

shallow (Crostale superficiale)

Impatto PAGER

red
> 1,000 fatalities

Feriti: > 5,000 · ~39.9M avvertito

Mappa interattiva di epicentro e faglie

6.26°N, 124.02°E
Faglia5 km
Cotabato Trench
Subduction Megathrust · ~15.0 mm/yr
Felt byMMI III+
~39.9M exposed
~27.8M strong shaking
Primary SolutionUSGS
USGS#usp0000hvbreviewed
1 agencies reporting
Setting6.3°N
Isola e fossa di Mindanao
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%Scossa principale17 ago22 ago27 ago1 set6 set11 set16 setM7.9
Hover or tap a point to inspect aftershocks and risk probability curve.
<35 km (superficiale)35–70 km (intermedia)>70 km (profonda)Scossa principale
Previsione di rischio ML:12h38%24h51%72h66%7d83%

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
Aftershocks: 49
High Omori aftershock probability
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
M7.9(Mw)Ref
33.0 kmRef
6.26°, 124.02°Origin
Authoritative
usp0000hvb

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 centri abitati

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

TownDistanceIntensity
Cotabato · Shariff Kabunsuan109 kmMMI VIII
General Santos · South Cotabato128 kmMMI VII
Pagadian · Zamboanga Del Sur186 kmMMI VII
Davao · Davao Del Sur201 kmMMI VII
Ozamis · Misamis Occidental210 kmMMI VII
Iligan · Lanao del Norte213 kmMMI VII

Tectonic setting

Nearest mapped active fault: Cotabato Trench, 5 km away, slip rate ~15.0 mm/yr (GEM Global Active Faults).

Profilo sismico regionale

Isola e fossa di Mindanao

Consulta il monitoraggio sismico live, i riferimenti storici di pericolosità, i modelli di scorrimento delle faglie e gli intervalli di ricorrenza per questa zona.