A GIS-BASED VOLCANIC HAZARD AND RISK ASSESSMENT OF ERUPTIONS SOURCED WITHIN VALLES CALDERA, NEW MEXICO PDF Download

Author: Rebecca Alcorn
Publisher:
ISBN:
Category : Geographic information systems
Languages : en
Pages : 71

Get Book Here

Book Description
Valles caldera, in north-central New Mexico, is considered one of the largest rhyolitic volcanoes in the United States due to the great amount of volcanic activity over the last 1.61 Ma. Although Valles caldera is currently dormant, there is potential for future volcanic activity, and therefore it is prudent to assess the risk to the surrounding area well before a disaster strikes. The primary objective of this study is to develop one of the first volcanic risk assessments of the Valles caldera region through the evaluation of the spatial extent of different volcanic hazards and the assessment of social and economic vulnerability of the area at risk. In this study, hazard maps are generated with a GIS-based volcanic hazards tool designed to simulate ash fallout, pyroclastic density currents (PDCs), and lava flows based on the Late Quaternary (~55 ka) eruptions from within Valles caldera. Simulated ash fall deposits originating from El Cajete crater are calibrated to isopach and lithic isopleth maps of the Lower and Upper El Cajete ash fall deposits as constructed by Wolff et al. (2011) with modern environmental conditions. Additionally, the calibration of PDCs is conducted based on the distribution and runout of the Battleship Rock Ignimbrite. Once calibrated, hazards are simulated at two other vent locations determined from probability distributions of structural features, in order to generate the final hazard maps. In assessing communities' hazard preparedness, social vulnerability is evaluated for all census-designated places within the study site through a principal component analysis of twenty-four variables shown to increase or decrease social vulnerability. Also, to assess the expected loss from hazards, economic vulnerability is evaluated through a multi-criteria evaluation (MCE) of population, land use, infrastructure, and economic production, where each factor is categorized and assigned a value representing relative vulnerability based on cost and importance. Ultimately, the hazard maps and vulnerability assessments are aggregated through weighted linear combination and pairwise comparison matrices, creating a total of five risk maps. Although the actual maps provide greater detail, overall, the risk maps show that ash fall has the greatest impact, effecting areas up to 50 km S/SE of the caldera, including highly vulnerable cities, such as Los Alamos, White Rock, and Santa Fe. The PDCs and lava flow hazards, however, impact significantly smaller areas, primarily disturbing low vulnerability forest. The methodology presented in this paper allows for a robust analysis of the risk the Valles caldera area is faced with in the event of volcanic hazards, which is especially useful in focusing mitigation strategies to reduce the loss from such hazard events.