Candra Malik & Fidelis E Satriastanti
Yogyakarta. Mount Merapi has broken its own record after erupting nonstop for more than 24 hours, and geologists are now calling this episode the mountain’s worst since the 1870s.
After erupting and spewing heat clouds since Wednesday morning, the mountain unleashed its most extreme volcanic activity yet on Thursday, sending ash seven kilometers into the air.
Geologists said Thursday’s eruption at 5:55 a.m. was five times stronger that the initial eruption on Oct. 26, which lasted only 33 minutes.
Having erupted almost daily for 10 days, Surono, head of the Volcanology and Geological Disaster Mitigation Agency (PVMBG), said this episode was considered Merapi’s worst eruption since the 1870s.
The 1872 eruption, which until now had been considered Merapi’s most violent in recent history, destroyed 13 villages and killed 1,400 people.
Later on Thursday, Surono said the heat clouds were spreading as far as 11.5 kilometers from the crater, dangerously near the edge of the expanded 15-kilometer danger zone, and lava was flowing into the mountain’s rivers.
“The heat clouds are moving more freely since Mount Merapi’s marathon eruptions, destroying houses, trees and anything else in the way,” he said.
“The temperature of the heat clouds is 600 to 800 degrees Celsius. Anyone who does not flee from the disaster zone will not be safe.”
Surono also called on people to keep a safe distance from rivers flowing from the slopes of Mount Merapi.
Heavy rain overnight triggered lahars, mixtures of water and rock debris, that cascaded down the Kuning, Gendol, Woro, Boyong, Krasak and Opak rivers on the slopes of the volcano, destroying a bridge and riverbanks.
“We’re concerned about public safety because there have been lahar flows and this can lead to flooding if they exceed the capacity of those rivers,” Surono said.
Raden Sukhyar, chief of the geology department at the Ministry of Energy and Mineral Resources, said there was still no indication when the eruptions would end.
“We still cannot ensure that the extreme catastrophic events on Thursday will mark a decrease in activity of Mount Merapi,” he said.
“We’re not going to drop its status from the highest alert because we don’t know when the eruptions will end.”
The eruptions have forced the residents of 32 villages within the disaster zone to evacuate.
Central Java’s governor, Bibit Waluyo, said more than 62,000 people from Magelang, Klaten and Boyolali districts had been forced from their homes, while Sri Purnomo, head of Sleman district in Yogyakarta, said his area had more than 22,000 evacuees.
The geologists warned that the dangers posed by the volcano extended beyond the people in the immediate danger zone.
Sukhyar said the volcano had spewed more than 50 million cubic meters of ash, sand and gravel.
“The winds tend to move to the west, taking volcanic ash toward Magelang, but it can spread anywhere depending on the wind direction,” he said.
Transportation Minister Freddy Numberi, speaking in Jakarta, said he had instructed airlines to direct all flights crossing Java to the north or south to avoid Merapi. “We have already prepared alternative routes for all flights,” he said.
“It may cost more and use up more fuel, but safety comes first.”
At least one hajj flight from Solo to Batam is known to have had engine trouble related to volanic ash.
Herry Bakti Gumay, director general of air transportation, said they had issued a warning last week to all airline operators with flights into Yogyakarta and would not withdraw it until conditions returned to normal.
However, the minister said airports in Yogyakarta, Solo and Semarang would remain open.
“If the ash covers the runways, then we will need to close them,” Freddy said.
“But they can be reopened after cleaning, which would take just a few hours.”