The phenomena caused by the devastating twin earthquakes in Venezuela are “unprecedented”, according to Efthymios Lekkas, Emeritus Professor of Dynamic Tectonics, Applied Geology and Natural Disaster Management at the National and Kapodistrian University of Athens and president of Greece’s Earthquake Planning and Protection Organisation.

His assessment is based on the findings of a Greek scientific mission to the affected areas, in which Panagiotis Karydis, Emeritus Professor of Earthquake Engineering at the National Technical University of Athens, also took part.

The mission’s aim was to provide scientific, technical, operational and humanitarian assistance following the disaster.

On June 24, two powerful earthquakes, measuring magnitude 7.2 and 7.5 according to the US Geological Survey, struck Venezuela’s coastal region, causing over two thousand deaths and injuries, extensive damage to buildings and critical infrastructure, and severe social and economic consequences.

According to the Greek team, the eight unprecedented phenomena recorded are as follows:

Two major earthquakes, 39 seconds apart

The two powerful earthquakes occurred within just 39 seconds of each other, a phenomenon described as unprecedented in seismological records. Other major twin earthquakes, such as those that struck Antakya, Turkey, in 2023, occurred at least six hours apart. In most other cases, the gap is usually measured in several hours or days.

A 300-kilometre fault zone was activated

The fault zone that caused the two earthquakes is at least 300 kilometres long. The San Sebastián Fault runs broadly east to west along Venezuela’s northern coastline and marks the boundary between the South American Plate and the Caribbean Plate. The activated faults are right-lateral strike-slip faults.

No damage near the epicentres

No damage was observed in the immediate vicinity of the epicentres, in the areas of San Felipe, Morón and Valencia. According to the Greek mission, even older buildings without seismic reinforcement remained intact.

Severe damage 200 kilometres away

By contrast, hundreds of collapses and extensive damage were recorded around 200 kilometres east of the epicentral area, in the coastal zone of La Guaira, the airport area, Catia La Mar and Caraballeda. These areas formed the macroseismic epicentre of the disaster’s impact.

Low-rise and high-rise buildings were both affected

The damage in these coastal areas affected both small, low-rise buildings and large high-rise structures of 20 to 30 storeys.

Caracas largely avoided major destruction

In Caracas, no widespread damage was recorded, apart from the collapse of around 10 large high-rise buildings — a very small number compared with the hundreds of thousands of structures that make up the urban fabric of Venezuela’s capital. Experts estimate that the fault zones running through Caracas belong to structures parallel to the northern fault zone and were not activated.

Resonance intensified the destruction

The high-rise buildings that collapsed along the coastline had been founded on loose coastal, river and stream deposits with a long natural period. These deposits resonated with the long-period seismic waves generated by the great distance from the epicentre, creating a catastrophic scenario that neither older nor newer buildings could withstand.

The situation was further aggravated by the duration of the shaking. Because the two earthquakes occurred so close together, buildings were subjected to several minutes of oscillation. Before the shaking from the first earthquake had ended, they were struck by the second, even stronger and longer-lasting motion.

Rocky neighbouring areas escaped systematic damage

Outside the narrow coastal zone, where specific geological, geotechnical and soil-mechanical conditions prevailed, adjacent areas built on metamorphic rock formations did not record systematic collapses or damage. According to the Greek mission, a completely different geodynamic framework developed there. Notably, even areas with very poor construction quality and high population density, including favelas, did not suffer significant damage.

According to the data available so far, the economic impact of the disaster is estimated at around 5% of Venezuela’s gross domestic product, underlining both the scale of the destruction and the challenges the country now faces.