Panama recorded 746 aftershocks following a magnitude 7.5 earthquake last week, as scientists investigate reported changes along the Pacific coast, local media reported Friday.

"According to theory and historical information, aftershocks from an earthquake of this magnitude can last between one and two months," Nestor Luque, director of the University of Panama's Institute of Geosciences, told the La Prensa newspaper.

Luque said the earthquake occurred at a depth of less than 10 kilometers (6.2 miles), with the energy released continuing to cause tectonic blocks to readjust. Seismic records showed that the aftershocks were gradually decreasing in magnitude, he said.

Luque added that earthquakes recorded in Chiriqui and Bocas del Toro were associated with separate fault systems and were not necessarily linked to the Oct. 9 quake.

Researchers are examining reports of changes along Panama's Pacific coast, where residents have observed exposed rocks and areas where the sea appears to have receded.

Luque explained that fault movements could cause coastal land to rise or sink, altering the shape of the surface.

Geologists will examine the affected areas to determine whether fault movements caused the reported changes, he said. Researchers are also investigating reports of changes in water color, including grayish tones.

Underground water may have come into contact with minerals released during the earthquake, but Luque said chemical tests were needed to establish the cause.

Residents of Isla Canas, in the southern province of Los Santos, reported that the island appeared to have split following the earthquake.

Luque said geologists would examine whether fractures extended across the island and reached the sea, which could provide evidence of fault movement.

The Institute of Geosciences estimates that strengthening seismic monitoring would require around 150 instruments, while a nationwide early-warning system could need 700 sensors.