Aftershocks after the earthquake are getting bigger

A building collapsed due to an earthquake in California
(Photo: aquarium.ucsd)

The aftershocks after earthquakes are getting bigger and happening on a much larger area than the previous conclusion, according to a study published in the British journal Nature.

Seismic researchers have looked at data on earthquakes that occurred in California, USA, from 1984-2002. They found that the aftershocks usually took place within five minutes after the earthquake and about 50km from the epicenter for earthquakes of between 2 and 4 Richter levels. In the conventional view, aftershocks occur due to changes in stratigraphic pressure.

However, the analysis of aftershocks in California shows that the signs of aftershocks are increasingly unclear and the stratigraphic pressure can spread to a very wide distance, like water waves when people I throw a pebble on the lake.

Q.HONG