1975 Haicheng Earthquake (M7.3) — The Only Successfully Predicted Major Quake

M 7.3Magnitude

4 Feb 1975Date

~1,328–2,041; ~150,000 evacuatedDeaths

At 7:36 p.m. on 4 February 1975, a magnitude 7.3 earthquake struck Haicheng, an industrial city in China's Liaoning province, rupturing a fault segment roughly 54 km long at a depth of about 15.6 km. Around 90% of the city's structures were significantly damaged or destroyed.

Rural Chinese town landscape, similar to Haicheng before the 1975 earthquake

What made Haicheng different was the days before the quake. A pronounced foreshock sequence from 1-3 February, with several shocks above magnitude 4, combined with reports of anomalous animal behaviour, groundwater changes and shifts in electrical resistivity, convinced Chinese seismologists to issue a formal warning. Local authorities ordered a mass evacuation, moving people out of buildings and into the open.

Makeshift winter tents at an evacuation camp, similar to the shelters used during the Haicheng evacuation

The evacuation is credited with preventing an estimated 150,000 additional deaths, making it the only time in recorded history that a major earthquake was successfully predicted and acted upon in advance at this scale. The warning came at a cost, however: 372 evacuees froze to death in improvised winter shelters and 341 died in quake-triggered fires, since many had been moved into unheated tents of branches, tarps and bedsheets during a harsh Liaoning winter.

Seismograph instrument recording earthquake data, the kind of monitoring credited with the Haicheng prediction

The success bred over-confidence: when a magnitude 7.6 earthquake struck Tangshan barely 18 months later, in July 1976, none of the same warning signs appeared beforehand and no evacuation was ordered. Tangshan killed an officially confirmed 242,000 people — a reminder, catalogued by USGS and Chinese seismological records, that the Haicheng prediction relied on a rare, unusually strong foreshock pattern that most large earthquakes never produce.

Frequently asked questions

How was the Haicheng earthquake predicted?

Seismologists tracked a strong foreshock sequence in the days before the quake, along with reports of unusual animal behaviour, groundwater changes and shifts in electrical resistivity, and used these signals to issue a formal warning and order evacuations.

How many lives did the Haicheng evacuation save?

Researchers estimate the evacuation prevented roughly 150,000 additional deaths, even though the earthquake itself still killed between 1,328 and 2,041 people.

Why did some evacuees still die?

Because people were moved out of buildings into improvised outdoor shelters during a harsh Liaoning winter, 372 evacuees froze to death and 341 died in fires triggered by the earthquake, despite the successful warning.

Can earthquakes reliably be predicted today?

No. Haicheng remains a rare case that relied on an unusually strong foreshock sequence; most major earthquakes, including Tangshan just 18 months later, give no such reliable warning signs.

How does Haicheng compare to the Tangshan earthquake?

Tangshan struck without any of the precursor signals seen at Haicheng and killed an officially confirmed 242,000 people, illustrating how rare a genuinely predictable earthquake sequence is.

What magnitude was the Haicheng earthquake?

It measured magnitude 7.3 on the surface-wave scale (about magnitude 7.0 on the moment magnitude scale), with a rupture roughly 54 km long.

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