Seismic Event Dossier•03:39 Local (01:39 UTC)(86y ago)

M 7.7 Earthquake
Covasna, Romania

A magnitude 7.7 (MW) earthquake occurred on 1940-11-10, 03:39 local time (01:39 UTC) (86y ago), centered ⁨52 km E of Sfintu-Gheorghe (Romania)⁩. The hypocenter was located at a deep depth of ⁨150 km⁩. Primary telemetry verified by ⁨USGS⁩.

Historical Landmark Earthquake

#94 of All Time

Curated Global Seismic Archive (1700–Present)

Top-100 Earthquakes

A magnitude 7.7 earthquake struck ⁨Covasna, Romania⁩ on November 10, 1940. Documented deaths: 1,000.

Documented Fatalities1,000Source: NOAA NCEI Significant Earthquake Database

Fault KinematicsActive fault

Equivalent Energy5.35 Mt TNT

Magnitude

M 7.7

5.35 Mt TNT

Depth

150 km

deep (Deep subduction)

PAGER Impact

yellow

10 – 100 fatalities

Injuries: 500 – 5,000 · ~149.3M felt

Interactive Epicenter & Fault Map

45.72°N, 26.43°E

Situation Monitoring

Continuous verification

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

Casualties

Damage assessment in progress

Tsunami Status

No tsunami threat

NOAA PTWC & regional buoys

Felt by

MMI III+

~149.3M exposed

~9.7M in strong shaking

Citizen Felt Reports

No felt reports submitted

Macroseismic DYFI verification

Primary Solution

USGS

USGS#iscgem901696reviewed

1 agencies reporting

Fault

155 km

Active Fault Segment

Slip · ~15.0 mm/yr

Geological Setting

45.7°N

Romania

Continental / Inland crustal

Multi-agency seismic telemetry active. Awaiting wire headlines.

Seismic Activity & Aftershock Sequence

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

Hover or tap a point to inspect aftershocks and risk probability curve.

<35 km (Shallow)35–70 km (Intermediate)>70 km (Deep)Mainshock

Agency Discrepancy Matrix (Cross-Network Verification)

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

Network / Source	Magnitude (Scale & Diff)	Depth & Diff	Epicenter & Shift (Δd)	Consensus	Data
USGS United States Geological Survey · Global / US	M7.7(Mw)Ref	150.0 kmRef	45.72°, 26.43°Origin	Authoritative

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.

Town	Distance	Intensity	Population
Sfintu-Gheorghe · Covasna	52 km	MMI VII	60,677
Focșani · Vrancea	59 km	MMI VII	105,112
Brașov · Brasov	64 km	MMI VII	311,044
Buzău · Buzau	69 km	MMI VII	130,954
Ploiești · Prahova	91 km	MMI VII	232,542
Miercurea Cuic · Harghita	100 km	MMI VII	42,029

Tectonic setting

Nearest mapped active fault: Active Fault Segment, , 155 km away, slip rate ~15.0 mm/yr (GEM Global Active Faults).

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M 7.7 Earthquake Covasna, Romania