SANTIAGO, May 4 (Xinhua) -- A string of more than 40 earthquakes in north-central Chile in the past day points to "unusual" activity, the deputy director of the National Seismological Center at the University of Chile, Mario Pardo, said Wednesday.

Four quakes stronger than magnitude 5 on the Richter scale have occurred in the last 24 hours in an area between the towns of Los Vilos and La Ligua, which is known for its high seismicity compared to the rest of the country, Pardo told local media.

"It is an area where earthquakes of this magnitude normally occur and, occasionally, large earthquakes like the ones we have had in the past, but what is unusual is that these earthquakes have occurred one right after the other, and at the same spot," he said.

Still, experts cannot predict when a large or small earthquake will occur, said Pardo.

The area's latest magnitude-5 quake was reported on Wednesday, 52 km southwest of Los Vilos, about 200 km north of the capital Santiago.

Situated on the so-called Pacific Ring of Fire, Chile is considered one of the most seismic countries across the world.