India, June 26 -- The earthquakes in Venezuela on Wednesday were unusual not just because of their size, but because they struck just 39 seconds apart, ruptured along the boundary between two tectonic plates and sent the strongest tremors towards the country's most densely populated coastline.

Follow Live| Venezuela earthquake death toll LIVE: 235 killed after mega 'doublet' earthquakes; hunt on for scores missing

The first earthquake measured magnitude 7.2, but instead of being followed by a series of smaller aftershocks, it was followed almost immediately by a larger magnitude 7.5 earthquake. Seismologists describe such events as an earthquake "doublet"-when two major earthquakes occur close together in both time and location.

The gr...