Numerical inversion and reconstruction of the tephra fallout deposits of the 1913 Plinian eruption of Volcán de Colima, México, based on best-fit with field data. Implications for hazard assessment
Abstract
Volcanic ash fallout represents a serious threat to people living near active volcanoes because it can produce several undesirable effects such as collapse of roofs by ash loading, respiratory sickness, air traffic disruption, or damage to agriculture. The analysis of tephra deposits allows for estimating some important parameters characterizing the eruption, such as the erupted mass, the column height and the bulk grain-size distribution. However the preservation of tephra deposits is often incomplete, especially for ancient eruptions, because the deposits can be buried or eroded. For these reasons, it is very useful to develop procedures that allow estimating reliably the parameters listed above, by using a minimum amount of data on the thickness and the grain-size distribution of the deposits. Computational models based on an analytical solution of a simplified advection-diffusion-sedimentation equation for volcanic tephra, can be used for this purpose for their simplicity of the physical parameterization, which allows high computation speed. These advantages allow for the solution of the inverse problem, which consists in a best-fit with field data, by carrying out thousands of runs in a relatively short time even on an ordinary personal computer. Solving the inverse problem allows for the estimation of crucial eruptive parameters, such as total erupted mass and column height. The eruptive history of Volcán de Colima shows that large magnitude eruptions occur every 100 years, like those events from 1606, 1690, 1818 and the most recent in 1913. Because the 1913 eruption represents the largest historic eruption of Volcán de Colima, it has been used as a reference to discuss volcanic hazards and risk scenarios connected to ash fallout. The model used for simulations, named HAZMAP, is a FORTRAN code, which solves the equation of diffusion, transport and sedimentation of volcanic lapilli and ashes. Simulations allowed us to produce: i) ash loading probability maps associated to a statistical set of daily wind profiles, ii) reference deposits relative to the main sectors and, iii) the estimate of the statistical probability of each deposit.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFM.V14C..03B
- Keywords:
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- 8404 VOLCANOLOGY / Volcanoclastic deposits;
- 8428 VOLCANOLOGY / Explosive volcanism;
- 8488 VOLCANOLOGY / Volcanic hazards and risks