Scientists keep eye on five raging volcanoes

Scientists keep eye on five raging volcanoes

The Jakarta Post, Bandung/Padang/Surabaya/Yogyakarta

Scientists anxiously watched five volcanoes nationwide on
Thursday, as fears over more natural disasters escalated with
four mountains rumbling into life over the past three days.

While thousands of refugees spent a third night in tents
having fled the slopes of Sumatra's Mount Talang, where hot ash
has been raining down since Monday, much attention focused on
Mt. Tangkuban Perahu, which is located near densely populated
Bandung city and only a few hundred kilometers east of Jakarta.

Next week Bandung will host more than 50 heads of state,
including China's president, at the Asian-African Summit.

While activity on the mountain decreased on Thursday compared
to a day earlier, biggest crater on the volcano, Domas, spewed
hot ash into the air 21 times.

"The earthquake frequency around the crater has dropped to 47
mild earthquakes compared to 100 earthquakes yesterday. But,
although the quake intensity has dropped, as a precautionary
measure, we are still closing the area near the crater to the
public," said Syamsul Rizal, the chief of a volcanology team
stationed at an observation post near the mountain.

With 11 mountains in the country on "watch status",
volcanologists were paying the closest attention to Mt. Tangkuban
Perahu, Mt. Anak Krakatau and Mt. Talang in West Sumatra, Mt.
Semeru in East Java and Mt. Merapi in Yogyakarta.

As of Thursday, activities in the five volcanoes had not
increased.

Syamsul said the Talang eruption and increased activities of
Tangkuban Perahu and Anak Krakatau were triggered by the giant
earthquakes in the Nias and Aceh regions recently.

"The tectonic earthquakes can trigger volcanic earthquakes
under several conditions, namely that the volcano has an open
crater, has its own fluid or gas sources, has shallow magma or if
the volcano is unstable. Needless to say, every volcano has its
own characteristics," Syamsul said.

This would explain why the earthquakes did not affect other
volcanoes located near their epicenters, he said. "It seems that
Tangkuban Perahu and Anak Krakatau are more unstable than those
that have been inactive for thousands of years," Syamsul said.

Anak Krakatau -- the "child" of the legendary Krakatoa that
blew itself apart in 1883 in one of the worst-ever natural
disasters -- was put on alert status late on Wednesday amid
warnings of poisonous gas emissions.

No one lives on Krakatau but the peak is a popular tourist
spot.

While petty traders on the sides of Tangkuban Perahu had been
evacuated despite the "watch" status, hundreds of thousands of
people living nearby the slopes of the volcano stayed put in
their houses, warily watching the smoking giant.

There have been 21 minor eruptions on the mountain since 1986.

In a separate development, a senior government official in
West Sumatra reported the Mt. Talang eruption on Tuesday had
caused losses to state plantation company PT Kebun Danau Kembar.

"We have to cease production as ashes have covered our tea
plantation," said Andre Tanjung, a manager at the company, adding
that the eruption cost the company about Rp 720 million a day
(US$80,000).

The 11 volcanoes under the watch of volcanologists are among
at least 129 active volcanoes in the country that are part of the
Pacific "Ring of Fire" -- a series of volcanoes and fault lines
encircling the Pacific Ocean and taking in the Americas, Japan,
Southeast Asia and New Zealand.