Environmental Impact Assessment of Explosive Volcanoes: A Case Study

Abstract

Although there are some parameters identified in the literature to quantify environmental impact of volcanic eruptions, e.g., Dust Veil Index (DVI), Volcanic Explosivity Index (VEI), and Volcanic Aerosol Index (VAI), no parametric studies have been undertaken to assess the environmental impact of explosive volcanoes. In this regard, this study deals with a parametric investigation of the environmental impact of the explosive volcanoes through some key parameters, such as (1) lateral blast effect, (2) debris avalanche effect, (3) lahars effect, (4) pyroclastic flow effect, (5) earthquake effect, (6) pyroclastic surge effect, (7) health effect, (8) tsunami effect, and (9) atmospheric effect. Considering these and their impact levels, a new parameter for explosive volcanic eruptions, so-called the “Environmental Impact Factor (EIF),” ranging from 0 to 1, is proposed as a function of the VEI which ranges between 1 and 8. We also conduct a quantitative evaluation of the environmental effects of the Mount St. Helens volcano (erupted on May 18, 1980) in USA. For this purpose, a case study for the St Helens eruption is conducted by taking into account the Volcanic Explosivity Index as 5, Environmental Correction Factor as 1.6, and the actual influence distances of the products and earthquake effect from the St Helens eruption. Of the above parameters, the first five parameter and also ash effect that can be commonly observed after the St. Helens eruption is considered. As a result of the analysis, the EIF will provide a quantitative record of environmental impact of the explosive volcanic products in terms of the influence distance and the VEI. Moreover, it is estimated that, in the case study, the environmental impact factors corresponding to the actual influence distances of the explosive products and earthquake effect become 0.568 in 12.8 km for lateral blast, 0.635 in 14 km for debris avalanche, 0.525 in 100 km for lahar, 0.875 in 8 km for pyroclastic flow, 0.978 in 16 km for ash (with an ash depth of 25 cm), and 0.921 in 1.6 km for earthquake effects.