LONG-RANGE VOLCANO ERUPTION FORECASTING PROGRAMME,

ERUPTION Pro 10.2

By R. B. TROMBLEY, Ph.D and JEAN-PAUL TOUTAIN, Ph.D2 Southwest Volcano Research Centre 3405 S. Tomahawk Rd., Suite # 31 Apache Junction, Arizona USA 85219-9169 (480) 671-1601 Copyright ©, 2001, Robert B. Trombley e-mail: swvrc@usa.net website: http://www.swvrc.org

Abstract

Forecasting the time, place, and character of a volcanic eruption is one of the major goals of volcanology. It is also one of the most difficult goals to achieve. The current goal in forecasting long-range volcanic eruptions, and the precept of this paper, is to provide the best possible long-range forecasts. The forecasting is based on the geologic history of the volcanoes under study as well as the day-to-day vital signs of the volcanoes in terms of surface deformation, micro-earthquakes, thermal imaging, frequency of eruption analysis, gas emissions, and a repose analysis. The software package, ERUPTION Pro 10.2 attempts to achieve these goals. ERUPTION Pro 10.2 performs a statistical analysis on loaded volcano eruption data from both historical and current real-time or near real-time data. It produces three forecasts; a statistically projected next eruption year, the next forecasted beginning eruption year with a >50% probability of eruption occurrence, and finally, the next forecasted beginning eruption year with a >95% probability of eruption occurrence. To date, the analysis for the years 1998 through 2000 have been completed. ERUPTION Pro 10.2 has been most favourable in its analysis capability, rendering an accuracy better than 90% since the incorporation of newer, improved algorithms beginning in late 1997. /

Introduction

Forecasting the time, place, and character of a volcanic eruption is one of the major goals of volcanology. It is also one of the most difficult goals to achieve. An experimental computer programme, specifically designed for the MS-DOS & Windows based PC computers (Trombley, 1990), in an attempt to forecast long-range volcanic eruptions, has been developed and tested over the past twelve years. This software programme is intended as an additional aid and diagnostic tool and is not intended as the definitive concept in forecasting an eruption of any particular volcano. It should be kept in mind that the software package ERUPTION Pro 10.2 certainly, at this point, is in no way infallible and only as good as the data used in creating it. This programme should not be used for volcanic hazard prediction or disaster mitigation by the public at this time but only as an indication that an eruptive event may occur with respect to all known and relevant data. Further, the ERUPTION Pro 10.2 software package's intent is to forecast, to the nearest year possible, with relevant available data, volcanoes about the world, primarily Strato, Compound or Complex, and Shield type volcanoes, the next eruption event. The term "forecast" is used as it lends itself to a more probabilistic and less precise connotation of a precise scientific prediction, which has the connotation of precision and is deterministic. The current state-of-the-art in the discipline of volcanic forecasting is far from precise. Furthermore, forecasting as used by ERUPTION Pro 10.2 has the notion of "may or probably" and not will erupt. This new application programme primarily uses the fundamental concept of the Poisson distribution paralleling the pioneering works of Wickman (1966) and De La Cruz-Reyna (1991). The difference lies in the application of dynamic Poisson distribution parameters in the programme as well as the conventional parameters of the Poisson distribution. As an eruption occurs, the database is immediately updated in ERUPTION Pro 10.2 or, if there is no eruption during the current year, the Poisson parameter, m, the calculated average eruption rate per year, is updated as each year passes. Currently, post-Holocene data for 490 volcanoes consisting of Strato, Complex, Compound and Shield volcanoes about the world, has been loaded into ERUPTION Pro 10.2 and analyzed. Data for submarine volcanoes3 has not been loaded as submarine volcanoes typically do not necessarily exhibit Poisson distribution characteristics and real-time or near real-time data is virtually impossible to obtain. Data was originally retrieved from the archives of the Smithsonian Institution in Washington, D. C.. The data was principally obtained from the "Volcanoes Of The World" works of Simkin, et al, (1981 & 1984) and updated with the new (2nd) edition of 1993, plus supplements, as well as documented direct eruption data from volcanic observatories about the world since 1989. ERUPTION Pro 10.2 performs analysis on loaded volcano eruption data from both historical as well as current real-time or near real-time data. It then produces three long-range forecasts; a statistically projected next eruption year, the next forecasted beginning eruption year with a >50% probability of eruption occurrence, and finally, the next forecasted beginning eruption year with a >95% probability of eruption occurrence. As for the case of the >50% and >95% probability calculations, ERUPTION Pro 10.2 solves this inequality for n years in the future where n is the minimum forecasted years for an eruption to occur beyond its last eruption with 50 and 95 percent probability respectively.

Defining Eruptions & Long-range Forecasts

Whenever the discussion of volcanoes arises, the subject of eruptions is inevitable. But just what constitutes an eruption of a volcano becomes a valid point and is, of course, of concern and importance to input data to ERUPTION Pro 10.2. In the 2nd Edition of "Volcanoes Of The World" (1993), by Simkin & Siebert, they define an eruption in the following manner, "The arrival of volcanic products at the Earth's surface is termed an eruption." Further, they go on to say, "..... we confine the term to events that involve the explosive ejection of fragmental material, the effusion of liquid lava, or both." And so is the premise for ERUPTION Pro 10.2. Only eruptions that produce pyroclastic materials, liquid lava or ash are considered and entered into the database. Reported phreatic eruptions, gaseous venting, "steaming", or fumarolic emissions are not considered an eruption with respect to the input data used by ERUPTION Pro 10.2. Input data sources concerning the type of eruption, and relevant data are principally provided by three sources of data. They are, the account record as reported and published in the "Volcanoes Of The World", The "Bulletin of the Global Volcanism Network", and direct reports from actual visits and/or reports from various volcanic observatories and/or other responsible volcanic reporting agencies about the globe. With respect to ERUPTION Pro 10.2's long-range forecasting ability, the term "long-range" used herein refers to the forecasting at least one (1) or more years in advance of an eruption event.

SWVRC ADVERTISEMENT

To our knowledge, it is the only software programme of its type anywhere in the world. "ERUPTION" Pro 10.2 performs analysis on current available volcano eruption data from both historical and current available eruption data, near real-time measurement data including, seismic, deformation, thermal, COSPEC, & statistical procedures. It produces three forecasts; a statistically projected next eruption year, the next forecasted beginning eruption year with an =>50% probability of eruption occurrence, and finally, the next forecasted beginning eruption year with an =>95% probability of eruption occurrence. This software engineering package has been under development for over ten years -- since 1989. "ERUPTION" Pro 10.2 is a continually developing computer programme, specifically designed for the PC type computer in MS-DOS or Windows format versions.

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