Two powerful earthquakes struck the area west of Venezuela’s capital Caracas just moments apart. The combination of the quakes’ strength, their close timing, and geographical proximity makes the event unusual even from a seismological perspective.

The first tremor was recorded shortly after 6 p.m. local time and was followed less than a minute later by an even stronger quake.

According to reports from the United States Geological Survey, the magnitudes were measured at 7.2 and 7.5 respectively. Both epicenters were also located very close to each other.

Seismologists describe the phenomenon as a so-called double earthquake, something that does occur but is rare. One possible explanation is that the initial earthquake altered stresses in the earth’s crust and thereby triggered the second one.

The limited depth of the quakes may also have contributed to the extensive damage. Earthquakes occurring near the earth’s surface typically cause stronger ground movements and therefore often have greater impact on buildings and infrastructure.

The first reports from authorities speak of a large number of dead and injured, but experts fear the final toll could prove to be significantly higher. International calculation models point to the risk of very substantial loss of life, although such forecasts are always associated with uncertainty.

The event is described as the most severe earthquake disaster in Venezuela in over a century. The country is located in a seismically active region where major earthquakes occur at long intervals, but when they do happen, the consequences can be extensive.