Two Earthquakes Hit North Venezuela Within Thirty-Nine Seconds of Each Other

North Venezuela has been hit by earthquakes over and over again. At 6:04 on Wednesday, a magnitude 7.2 earthquake struck Northern Venezuela, followed closely by a magnitude 7.5 quake, 39 seconds later. These “doublets” are already uncommon among Venezuela, but this one was extraordinary.

Usually, the foreshock will come first. However, after some time-typically more than 39 seconds later–the main shock will occur. Brandon Bishop, a seismologist at Saint Louis University, said, “Most doublets don’t occur quite this close together in time. Delays of hours to a few days are much more common.” The timing is almost certainly not a coincidence. “It is very likely that the first triggered the second one,” said Harold Tobin, the director of the Pacific Northwest Seismic Network at the University of Washington. Some seismologists think that the first rupture caused the second one, hence the rapid timing of the earthquakes.

Although a magnitude 7.2 quake seems less devastating than a magnitude 7.5 event, the main shock-the magnitude 7.5-released almost three times the energy as the foreshock. This shows that the scale isn’t linear. The earthquakes took place in Yaracuy Valley that is filled with loose sediments, the kind that tends to amplify shaking. This led to landslides in the aftermath, destroying even more homes.

The fault rupture moved towards the capital city of Caracas. It “got a direct hit” says Stephen Hicks, a seismologist at University College London in England.

These earthquakes have also triggered many aftershocks, according to the forecasts by the U.S. Geological Survey, and the area will be hit by many lesser earthquakes: around magnitudes of 3 to 5.

“Normally, aftershocks occur most frequently right after a big one, then tail off exponentially over days to weeks to years,” said Dr. Tobin. That means the chaos and fear gripping the nation right now is likely to continue well into the future.