M

ount Merapi, which stands on the border between Yogyakarta and Central Java, has shown heightened volcanic activity over the past few days, spewing incandescent lava from its crater.

Sidorejo subdistrict head Jemakir said that apart from incandescent lava, the volcano was emitting booming sounds resembling thunder more frequently, which had prompted local residents to also increase the frequency of their independently organized patrols.

“The people are still calm because the lava so far has flowed only 500 to 800 meters down the slope. But we remain alert, in case Merapi erupts,” he said on Tuesday.

Sidorejo subdistrict extends to the slopes Mt. Merapi in the northern part of Klaten regency, Central Java.

Dimas Joko, a volunteer monitoring Mt. Merapi, said that the volume and the extent of the lava flow were both relatively normal, but that the volunteer team had banned all human activity within a 3-kilometer radius from the crater.

“They may [still] harvest grass or farm, but they are not allowed within a radius of 3 km from the crater,” he said.

Citing recommendations from the Center of Volcanology and Geological Hazard Mitigation, Joko said that people were advised to stay away from the upper slopes of the mountain for their own safety, especially considering the lava flow.

Mt. Merapi’s warning status on Tuesday was still Waspada (Caution), the second of the four-tiered national volcano alert system that has been in place since May 2018.

The Central Java Disaster Mitigation Agency (BPBD) is working with other regencies to prepare evacuation routes and emergency shelters in anticipation of a major eruption.

Central Java BPBD head, Sarwa Pramana, stated that the established Mt. Merapi evacuation routes were heavily damaged, because of the hundreds of trucks transporting volcanic ash. The area was also seeing rainfall almost daily, which had worsened conditions.

“Restoring the evacuation routes is very urgent, especially in Klaten. The routes are needed to evacuate people when Merapi’s alert level reaches Awas [Danger],” he said.

Sarwa said the most heavily damaged evacuation routes in Klaten included the routes in Kemalang, Manisrenggo and Karangnongko districts. The agency had proposed a budget of Rp 100 billion (US$7 million) to repair the routes.

“I heard that the fund had already been disbursed. Hopefully, construction can begin soon,” he said.

Sarwa added that the agency had started calculating logistical needs in case the eruptions worsened, including masks, community kitchens, emergency tents and rehabilitation posts.

“[The calculations] are necessary for smoother mitigation [efforts] at the time of a disaster,” he said. Central Java BPBD had also installed three additional CCTV cameras in Klaten, Magelang and Boyolali to monitor the volcano.

One of the world’s most active volcanoes, Mt. Merapi is located at the point where four regencies meet: the Central Java regencies of Magelang, Boyolali and Klaten, and Sleman regency in Yogyakarta.

The last major eruption of Mount Merapi occurred in 2010, killing 275 people, most of whom died because of the pyroclastic flows, and displacing 350,000 others. Most of the victims lived on the volcano’s slopes.

On May 11, 2018, Merapi suddenly erupted in what disaster mitigation officials called a “non-dangerous” phreatic eruption, a phenomenon caused by the heating and expansion of groundwater.

The sudden eruption at that time had caused no casualties and authorities declared the mountain’s status as “normal”.

But nine days later, authorities raised the alert status for Merapi from normal to caution, the third-highest level, following a string of phreatic eruptions.

The main reason behind the decision was the anticipation of possible magmatic eruptions in the future, particularly given that one of three phreatic eruptions on Monday was in fact followed by certain tremors known to be among the precursors to explosive magmatic eruptions on Merapi.