nature & planetWikipedia1940 · Vrancea, Romania

Romania's strongest 20th-century earthquake came from 133 km underground

the gist

On 10 November 1940 a magnitude 7.7 earthquake struck the Vrancea region of Romania at 3:39 a.m., while most people were at home. It was the strongest earthquake recorded in Romania in the 20th century. Its focus lay about 133 kilometres deep, which spread strong shaking over a wide area: the greatest damage covered 80,000 square kilometres, and effects were felt across more than 2 million square kilometres, from Leningrad to Greece and from Warsaw to the Moscow area. Bucharest, to the south, suffered serious damage.

how it works

The quakes are produced by a slab of old oceanic crust that sank into the mantle below the Carpathians. Because the rupture occurs deep inside the slab, seismic waves travel far through cold, hard rock before they reach the surface.

so what

Vrancea is the only place in Europe where deep earthquakes this strong occur regularly, which is why Bucharest is a high-risk capital. Another major quake there in 1977 killed more than 1,500 people.

fun fact

Vrancea quakes happen where a sinking piece of the earth's crust lies under the Carpathian Mountains.

From Wikipedia, the free encyclopedia · text CC BY-SA 4.0

Illustrative photo · Iosif Berman, Public domain, via Wikimedia Commons