Geologists say that recent earthquakes near Guayaquil mean less chance for a ‘big one’

According to geologists, the series of earthquakes near Guayaquil in recent weeks may help prevent much more powerful earthquakes in the future.

Guayaquil residents gather on the street following a recent earthquake.

According to Carlos Chon, president of the Ecuadorian Society of Earthquake Engineering, the earthquakes of the past three weeks are most likely the result of the Nazca tectonic plate moving against the South American plate. “There is constant pressure where the two plates meet and when the Nazca slides under the South American plate it creates tremors,” he said. “The small or medium earthquakes we have experienced are an indication that pressure is being relieved.”

He added: “We would have much more to worry about when there is no earthquake activity since we know that pressure could be building for a catastrophic event.”

Seismologist Sandro Vaca of the Geophysical Institute (IG) agrees but says that it impossible to know for certain the source of the recent earthquakes. “There are many small faults in the area, not just the Nazca, but they often interact” she says. “The best example of this is the the Puná-Pallatanga fault, south of Guayaquil. When there is movement on the Nazca plate, there is often complimentary movement on Puná-Pallatanga.”

Based on IG calculations, there have been six earthquakes since November 15 in the Guayaquil area, ranging from 3.2 to 5.8 on the Richter scale.

The Nazca plate is one of the fastest moving tectonic plates in the world, say Chon, moving southwest at 46 mm per year. “This explains the frequency of earthquakes along the South American coast. It also explains the power of the quakes,” he says, pointing out that the largest earthquakes in modern times have occurred in Chile and Peru.” The largest quake ever recorded, measuring 9.5 magnitude on the Richter scale, occurred in southern Chile in 1960.

“In Ecuador, we were reminded of the power of the Nazca plate subduction last year with the 7.8 earthquake on the north coast,” Chon said.