Predicting Topographic Collapse Following Lava Dome Growth Using High-Resolution PlanetScope Images in Indonesia

Abstract This study describes a rare case of lava dome growth at Mt. Ibu in West Halmahera Regency, North Maluku Province, Indonesia that filled the inner crater and even exceeded the outer crater rim at the northern flank. The lava dome growth caused concern due to the rapid volumetric change, which is usually followed by topographic collapse, producing hazardous pyroclastic flows and debris avalanches. Based on the condition of Mt. Ibu, we calculated the lava dome area and volume of Mt. Ibu using PlanetScope images and a national digital elevation model, respectively. Comparing the lava dome volume to the crater space, we tried to predict the area and time of the future topographic collapse. We calculated the time series of the lava dome volume from January 2020 to August 2022 to predict the time of the maximum volume of the outer crater rim using autoregressive integrated moving average (ARIMA) and seasonal autoregressive integrated moving average (SARIMA) models. According to the time series, Mt. Ibu was beyond the critical conditions for collapse when the volume of the lava dome reached the outer crater rim by approximately 0.114 km3 or an area of 1.47 km2. Then, the ARIMA and SARIMA predictions were estimated convergently, and the critical condition was predicted to be achieved in 2037. The confidence level of the ARIMA model was presented by the root mean squared error (0.008 km2) and mean absolute percentage error approximately (0.554%). Moreover, for the SARIMA model, these values were approximately 0.009 km2 and 0.397%, respectively.