Behind Venezuela’s quake devastation: Rare ‘seismic doublet’, vulnerable location, Pg12

Key Highlights:

• A seismic doublet of earthquakes, with magnitudes 7.2 and 7.5, struck near Caracas, Venezuela.
• The two quakes occurred just 39 seconds apart, with the second being the largest to hit Venezuela or its coast since 1900.
• Preliminary estimates suggest tens of thousands of fatalities, potentially making it one of Venezuela's deadliest natural disasters.
• The U.S. Geological Survey (USGS) classified the event as a seismic doublet due to the close timing and proximity of the two major quakes.

Venezuala.png

Detailed Insights:

• The first earthquake struck near San Felipe in Yaracuy state, while the second hit near Moron in Carabobo state.
• Tremors from the disaster were felt as far away as neighboring Colombia and parts of Brazil, including Manaus and Bogota.
• Venezuela's President Delcy Rodriguez identified Caracas and the north-central states of Miranda, La Guaira, Aragua, Carabobo, and Falcón as the worst-affected regions.
• The earthquakes resulted from shallow strike-slip faulting near the boundary between the Caribbean and South American tectonic plates.
• The shallow depth of approximately 10 km meant that shockwaves reached the surface with high intensity, contributing to the widespread destruction.
• Seismic doublets are particularly destructive because they prolong strong ground shaking, increasing the risk of collapse for structures already weakened by the initial quake.
• Past examples of such events include a 2023 doublet in Turkey and Syria (magnitudes 7.8 and 7.7) and a 2021 event in the Indian Ocean (magnitudes 8.6 and 8.2).
• Venezuela is situated in one of the most seismically active regions in northern South America.

Key Concepts Involved:

• Seismic Doublet: Two earthquakes of similar magnitude that originate from distinct but closely related ruptures and occur in quick succession.
• Strike-slip fault: A type of fault where two blocks of the Earth's crust slide horizontally past each other.
• Tectonic Plates: Large, rigid slabs of the Earth's lithosphere that are constantly moving and interacting.
• Foreshock: A smaller earthquake that precedes a larger, main earthquake in a seismic sequence.
• Mainshock: The largest earthquake in a seismic sequence, often followed by aftershocks.