LLUNPIY Preliminary Extension for Simulating Primary Lahars - Application to the 1877 Cataclysmic Event of Cotopaxi Volcano

Abstract

Cotopaxi volcano is one of the most studied and surveyed volcanos in the world because the repetition of the 1877 catastrophic lahar invasion, is not implausible, threatening now more than 100,000 persons. A reliable forecasting tool is very important for projecting security measures. LLUNPIY is a Cellular Automata model for simulating lahars in terms of complex system evolving on the base of local interaction. Here, LLUNPIY extension is applied to Cotopaxi event of 1877 primary lahars, after the successful simulation of some secondary lahars of Tungurahua volcano. Such an extension permitted simulations with different initial hypotheses: our preliminary simulations agree in outline with field studies about the evolution of event, moreover LLUNPIY permits a broader approach to overall phenomenon in comparison with other tools.

LLUNPIY Simulations of the 1877 Northward Catastrophic Lahars of Cotopaxi Volcano (Ecuador) for a Contribution to Forecasting the Hazards

“…The inclusion of the erosion process during the lahars' downstream motion represented a numerical breakthrough delivered by the adoption of a CA approach to the development of semiempirical computational models simulating surface flows [15]. The CA approach was actually derived from the previous SCIDDICA (Simulation through Computational Innovative methods for the Detection of Debris flow path using Interactive Cellular Automata) model [18][19][20][21] for the simulation of debris flows. Moreover, it constitutes a parallel computational paradigm for modeling complex dynamical systems, whose evolution is mainly due to the interactions among their constituent parts.…”

“…The present LLUNPIY model (lahar modeling by local rules based on an underlying pick of yoked processes, from the Quechua word "llunp'iy", meaning flood) is based on the CA computational paradigm for simulating primary and secondary lahars according to a general methodology developed for surface flows [19]. LLUNPIY was applied and validated in its various versions to past volcanic events, such as the 2005 and 2008 secondary lahars of Vascún Valley, Tungurahua Volcano, Ecuador [20][21][22][23][24][25], as well as the 1877 lahars flowing along the Río Cutuchi, Cotopaxi Volcano [20], and it was also applied to forecast future probable events [26,27].…”

“…In our paper, we applied two variations of the LLUNPIY model: (i) the first is an adaptation of the basic version, where the sudden and homogeneous melting of the summit glacier of the volcano occurs at the first step of the simulation [20]; (ii) the second adds to the previous one an "external influence" [13], i.e., the volcano's icecap is first melted partially and locally in correspondence with landing points where the free-falling pyroclastic bombs impact the glacier during a number of LLUNPIY steps, corresponding to the "bombing" duration; the number of bombs is constant at each step, and a stochastic function determines the drop coordinates on the icecap struck by bombs.…”