One of the Philippines' most active volcanoes rumbled to life on Tuesday, spewing room-sized rocks toward nearly 30 surprised climbers, killing five and injuring others who had to be rescued by helicopters.

The climbers and their Filipino guides had spent the night camping in two groups before setting out at daybreak for the crater of the Mount Mayon volcano when the sudden explosion of rocks, ash and plumes of smoke jolted the picturesque mountain, guide Kenneth Jesalva told the ABS-CBN TV network by cellphone.

He said rocks "as big as a living room" came raining down, killing and injuring members of his group, some of whom were in critical condition. Jesalva said he rushed back to the base camp at 914 meters to call for help.

Among the dead were three Germans and their Filipino guide, said Albay provincial Governor Joey Salceda. He said everyone on the mountain except for one foreigner had been accounted for at midday. The foreigner is presumed dead.

Eight people were injured, and Salceda said the others were in the process of being brought down the mountain. Ash clouds have cleared over the volcano, which was quiet later in the morning.

"The injured are all foreigners. ... They cannot walk. If you can imagine, the boulders there are as big as cars. Some of them slid and rolled down. We will rappel the rescue team, and we will rappel them up again," Salceda said from Legazpi, the provincial capital.

An Austrian mountaineer and two Spaniards were rescued with small bruises, he said.

Tuesday's eruption was normal for the restive Mayon, said Renato Solidum, the head of the Philippine Institute of Volcanology and Seismology.

The 2,460-meter mountain, about 340 km southeast of Manila, has erupted about 40 times in the last 400 years.

In 2010, thousands of residents moved to temporary shelters when the volcano ejected ash up to 8 km from the crater.

Solidum described the eruption as a 73-second "steam-driven minor explosion" that was not expected to be repeated anytime soon.

Solidum added that people living around Mayon did not need to evacuate. He said the explosion was triggered when rainwater made contact with hot ash deposits on the crater mouth.

"There is no magma activity. Essentially what happened today is a normal process of a steam-driven explosion," Solidum said.

Climbers are not allowed when an alert is up, and the recent calm may have encouraged this week's trek. However, Solidum said that even with no alert raised, the immediate zone around the volcano is supposed to be a no-go area because of the risk of a sudden eruption.

Salceda said he will enforce a ban on climbers.

Despite the risks, Mayon and its near-perfect cone is a favorite spot for volcano watchers. Most enjoy the occasional nighttime spectacle of the rim lit by flowing lava, viewing from the safety of hotels in Legazpi.

The volcano has a trail to the crater that is walkable though it's steep and strewn with rocks and debris from past eruptions.

AP-AFP

(China Daily 05/08/2013 page10)