Venezuela’s Quake Devastation

Behind Venezuela’s Quake Devastation: Rare ‘Seismic Doublet’, Vulnerable Location

Venezuela was hit by twin earthquakes near its capital Caracas, causing large-scale devastation. The first quake of magnitude 7.2 was followed just 39 seconds later by a stronger magnitude 7.5 quake. The US Geological Survey described the event as a rare “seismic doublet.”

 What Happened in Venezuela?

• Two powerful earthquakes struck near Caracas.
• The first quake occurred about 160 km west of Caracas.
• The second quake followed within seconds and was stronger.
• The tremors were felt in neighbouring Colombia and parts of Brazil’s Amazon region.
• Caracas and north-central Venezuelan states such as Miranda, La Guaira, Aragua, Carabobo and Falcón were among the worst affected.

What is a Seismic Doublet?

• A seismic doublet refers to two earthquakes of similar magnitude occurring close to each other in time and location.
• Unlike a normal earthquake-aftershock sequence, both earthquakes in a doublet are strong and closely related.
• In this case, the 7.2 magnitude quake was treated as a foreshock, while the 7.5 magnitude quake was considered the main shock.

 What Caused the Earthquakes?

• Venezuela lies in a seismically active zone in northern South America.
• It is located near the boundary of the Caribbean Plate and the South American Plate.
• These plates slide horizontally past each other along faults.
• The earthquake resulted from shallow strike-slip faulting near the plate boundary.

Why Were the Quakes So Destructive?

• The earthquakes occurred at a shallow depth of about 10 km.
• Shallow earthquakes allow seismic waves to reach the surface with high intensity.
• Since the event was a doublet, shaking lasted longer than a normal earthquake.
• Prolonged shaking can cause more damage to already weakened buildings and infrastructure.

 Doublet vs Aftershock

• An aftershock is usually smaller than the main earthquake.
• A doublet involves two strong earthquakes of similar magnitude.
• In Venezuela’s case, the second quake was stronger, making it more destructive.

 Examples of Past Doublets

• Turkey-Syria, 2023: Two major quakes of magnitude 7.8 and 7.7 caused widespread destruction.
• Indian Ocean, 2012: Two large quakes of magnitude 8.6 and 8.2 occurred near Sumatra.
• Australia, 1988: A rare “triplet” sequence of three earthquakes occurred within hours.