CNN reviewed and verified dozens of videos from Venezuela’s two deadly earthquakes and found many residential towers had ‘pancaked.’ But why is it so lethal when buildings collapse this way?

A series of earthquakes have brought down buildings in Venezuela's capital Caracas, causing scientists to estimate "high casualties and extensive damage" to the South American country.

The first quake hit just after 6pm on Wednesday evening (Thursday AEST) with a magnitude of 7.1.