Geological Agency Reveals Real Threat of Magnitude 7 Earthquake from Lembang Fault Activity
Indonesia’s Geological Agency within the Ministry of Energy and Mineral Resources has warned that the potential earthquake threat from Lembang Fault activity presents a genuine risk that must be anticipated seriously through sustained mitigation measures.
Supartoyo, a Senior Earth Investigator at the Centre for Volcanology and Geological Hazard Mitigation (PVMBG), stated that earthquakes with magnitudes of 6.8–7.0 could occur if the entire 29-kilometre Lembang Fault segment ruptures.
“If the entire segment moves, the potential magnitude could reach 6.8 to 7. This forms the basis for developing worst-case scenarios for contingency planning,” he said in Bandung on Thursday 26 February.
According to Supartoyo, such a scenario occurring near the fault zone would result in ground acceleration estimated between 0.6 and 0.8 g, with vibration intensity expected to exceed VIII on the Modified Mercalli Intensity Scale.
Scale VIII MMI falls into the heavy damage category, characterised by light damage to well-constructed buildings, cracks in ordinary buildings, walls separating from frames, and collapse of chimneys and monuments. Such earthquake vibrations cause people to panic, knock over furniture, and make well water turbid.
Supartoyo noted that these conditions could cause significant damage, particularly to buildings not designed to earthquake-resistant standards.
“Areas near the fault line are vulnerable to very strong shaking. Non-engineered buildings would certainly be highly susceptible,” he said.
He also explained that earthquake impact is determined not only by magnitude but also by proximity to the earthquake source, hypocentric depth, local geological conditions, and the quality of building construction.
“Magnitude is not the only factor. Proximity to the earthquake source and soil conditions significantly influence the level of damage that occurs,” he said.
According to Geological Agency data, destructive earthquakes in Indonesia between 2000 and 2025 have ranged from five to 41 incidents annually.
As of now in 2026, six destructive earthquakes have been recorded based on data compiled from various sources, including the National Disaster Management Agency.
Several major earthquake events in Indonesia have demonstrated significant economic impacts, such as the 2006 Yogyakarta earthquake causing losses of approximately Rp29.2 trillion, the 2004 Aceh earthquake and tsunami approximately Rp13.4 trillion, the 2018 Palu earthquake approximately Rp8.5 trillion, and the 2022 Cianjur earthquake approximately Rp4 trillion.
Mitigation is essential
Supartoyo noted that such losses occur from disasters lasting only minutes—sometimes less than 15 minutes—but creating long-term impacts on social life and regional development.
“Losses can equal a region’s annual development budget. Therefore, mitigation must be viewed as an investment, not a burden,” he said.
He emphasised that mitigation must be conducted according to Law Number 24 of 2007 on Disaster Management through structural and non-structural approaches.
Structural mitigation includes construction and strengthening of earthquake-resistant buildings, whilst non-structural mitigation covers public education, simulations, training, and regulatory development.
“Earthquakes cannot be prevented, but their risks can be reduced if disaster preparedness and construction standards are applied consistently,” he said.
Given that the Lembang Fault lies near densely populated areas in Greater Bandung, Supartoyo stressed that mitigation measures can no longer be delayed to minimise casualties and economic losses.