Mount Semeru has once again shown a significant increase in volcanic activity following a series of eruptions since June 20. According to data from the Center for Volcanology and Geological Hazard Mitigation (PVMBG), the highest volcano on Java Island is now officially at Level III (Alert), demanding extra vigilance from local residents.
Dr. Indranova Suhendro, S.T., M.Sc., a geography expert from Universitas Gadjah Mada (UGM), emphasized that the danger from Semeru is not limited to ejected materials during eruptions. According to him, the threat of lahar floods is actually the most tangible risk. Volcanic materials such as sand, gravel, and boulders accumulating on the mountain slopes can be suddenly swept by rainwater into river streams, even when the downstream areas are not experiencing rain.
Scientifically, Nova explained that Mount Semeru's magma is quite viscous with high crystal content. This condition forms a lava dome that is prone to collapse, triggering pyroclastic density currents, locally known as "wedhus gembel". The combination of high rainfall and magma pressure from below the crater further increases the potential instability of the lava dome.
Regarding the ongoing sand mining activities around the lahar flow paths, Nova acknowledged the dilemma between local residents' economic needs and their safety. Although scientifically highly dangerous, he suggested a realistic approach of strengthening strict workplace safety standards for miners to minimize fatal risks.
In closing, he reminded residents living in disaster-prone areas to always comply with instructions from relevant authorities. Understanding the characteristics of the volcano as a dynamic natural entity is the key to building effective disaster mitigation for communities living at the foot of Mount Semeru.
