Quantitative impact assessment of the 2019 tropical cyclone Kammuri lahars: Mayon volcano, Philippines

Abstract

Lahars (volcanic mudflows) are frequent occurrences in communities near active Philippine volcanoes due to intense and prolonged rainfall. Mayon Volcano is the most active volcano in the Philippines, ejecting pyroclastic deposits that serve as erodible materials for lahars. Damaging lahars have occurred in the past, with the more recent ones in 2006, 2015, 2019 and 2020 posing impacts such as erosion, burial, and flash flooding in low-lying areas. This paper presents the results of an interdisciplinary case study on lahar impact assessment for a selected pilot community at Mayon Volcano. Lahar hazard modeling, an exposure database, and a Filipinized lahar damage state table were combined to estimate potential lahar impacts to buildings for the study area using a lahar impact assessment software tool called REDAS Quick Lahar Impact Simulation Tool (REDAS-QLIST). The tool can estimate lahar losses such as physical damage, economic loss, and total population affected including age-sex distribution. Being able to accurately quantify impact and damage is one of the added values provided by REDAS-QLIST. The damage and loss estimates produced for our case study area were tested using an actual lahar event scenario from Tropical Cyclone (TC) Kammuri in 2019. Stakeholders, especially from local government units, can utilize the methods and results presented to plan and apply adaptable and sustainable disaster risk reduction programs in their communities. Importantly, the methodology can be used with additional lahar modeling results and exposure data through the REDAS QLIST to assess hazard and loss for other volcanic regions in the Philippines.