Mount Semeru status increased to alert

The alert status of Mount Semeru in Malang and Lumajang regencies, East Java, was increased from “siaga” (third level) to “waspada” or “alert” (second level) on Thursday following increased volcanic activity from the 3,676-meter volcano.

Head of the Volcanology and Geological Disaster Mitigation Center’s (PVMBG) volcano monitoring division, Muhamad Hendrasto, said that the higher alert status was applied based on both visual observations and increases in Semeru’s volcanic earthquake frequency.

“On Feb. 2, the observation stations spotted pyroclastic flows speeding down to 2,500 meters below the Jongring Seloko crater,” Hendrasto told reporters in Bandung, West Java, on Friday.

From Dec. 29, 2011 to Jan. 15, 2012, the center recorded eight thick, grayish ash explosions from the Jongring Seloko crater, which launched materials between 100 and 600 meters above crater rim.

Semeru’s earthquake activity is accordingly increasing. Over the last two days, the center recorded four pyroclastic earthquakes, 22 avalanche earthquakes, 128 blast earthquakes and two distant tectonic earthquakes.

Hendrasto asked local administrations and people to be cautious of volcanic materials and searing stones that could be thrown for distances up to a few kilometers from the crater, including the Mahameru area.

The PVMBG therefore recommended local administrations to ban their respective people from approaching the crater, and maintain a four-kilometer safety radius around the crater.

PVMBG covers Rowo Baung and Supit villages in Pronojiwo subdistrict, Pronojiwa district in Lumajang regency and Urip village in Sumber Urip, as well as Kamar A and Umbulandi villages in Supit Urang subdistrict, Lumajang, as regions that could be potentially affected by volcanic materials, pyroclastic flows and lahar.

“Rowo Baung and Supit are the closest villages to the center of eruptions and are located less than nine kilometers from the peak of Semeru,” Hendrasto said.

He added that rivers potentially affected by pyroclastic flows and lahar were Besuk Bang, Kobokan and Besuk Kembar Rivers.

The biggest pyroclastic flow ever spewed by Semeru was recorded on Dec. 31, 2002. It spilled into the banks of Besuk Bang River, speeding down the riverbed for some 11 kilometers, displacing 501 people.

On May 5, 2009, the status of Semeru was also increased to alert but was later put back to siaga on July 16 the same year.