Cedric Daep, provincial public safety and emergency management office head, said some 26,283 persons are at risk from lahar in the towns and cities around the volcano.
Some 13 million cubic meters of pyroclastic deposits had clogged river channels in several barangays surrounding Mayon. These deposits are expected to soften due to rains and turn into lahar.
Volcanologists say the lahar threat is aggravated by defective rain gauges which no longer provide accurate warnings.
Renato Arevalo, chief of the Office of Civil Defense (OCD) told The STAR that the Japan International Cooperation Agency has installed rain gauge stations in Mabinit, Buyoan, Sta. Magdalena and at the Mayon Resthouse. These gauges are connected to a computer console at the OCD regional office and at the Department of Public Works and Highways’ regional office.
"When we conducted a simulation drill last year to determine how accurate the readings in our computers we were surprised because there were different readings," said Arevalo.
As a result, technicians from the Japan Radio Corp. came over and made adjustments to the computer programs, which was designed under Japanese conditions.
He said the four rain gauges were installed about four to five years ago with the help of JRC technicians.
"I also asked the help of barangay officials to help watch our equipment there," said Arevalo. He added that some residents stole the rain gauges in the past.
Until now Arevalo’s office is still coordinating with the JICA to improve lahar monitoring around Mayon.