On the probability of future plinian eruptions at the Central American Volcanic Arc: a statistical time series analysis.

Wehrmann, Heidi, Dzierma, Yvonne, Kutterolf, Steffen and Schaller, T. (2012) On the probability of future plinian eruptions at the Central American Volcanic Arc: a statistical time series analysis. [Talk] In: The Lübeck Retreat, Collaborative Research SFB 574 Volatiles and Fluids in Subduction Zones: Climate Feedback and Trigger Mechanisms for Natural Disasters. , 23.-25.05.2012, Lübeck . The Lübeck Retreat: final colloquium of SFB 574; May 23-25, 2012: program & abstracts. ; pp. 36-37 .

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Plinian eruptions belong to the most devastating types of volcanic activity, thus posing a dramatic
hazard for people and property far beyond the immediate surroundings of a volcano. Assessing
volcanic hazards consists of a number of aspects. First, detailed isopach and isopleth mapping of
past eruptions' deposits facilitates to constrain typical eruption behaviour in terms of eruption
magnitudes, intensities, and affected areas. The second component integrates a variety of
surveillance techniques, including seismic recording, compositional and thermal monitoring of
quiescent gas emissions, ground deformation, etc. In many cases such monitoring efforts can signal
that a volcano is building up towards an eruption, and may allow for a timely alert and mitigation
actions. In addition to the knowledge on expected consequences an eruption might entail, and to the
recording of physical processes, the hazard and risk evaluation strongly depends on the likelihood
that an eruption may happen. It is therefore of pivotal interest to understand the chronological
character of a volcano or a volcanic area. Statistical time series analyses of eruption records provide
a powerful tool for meeting the growing demand for probabilistic eruption forecasting.
The Central American Volcanic Arc (CAVA) has been site of numerous exceptionally explosive and
voluminous plinian eruptions over the past 200 000. We here process the long-term plinian eruption
record of the subduction system by statistical means, considering felsic and mafic eruption sequences separately. After ensuring that the necessary conditions for the analysis are fulfilled, the Kaplan-Meier
method is applied to estimate survival functions. Subsequently, the exponential, the Weibull, and the
log-logistic distribution are fit to the data. All functions are confirmed by goodness-of-fit tests to
describe the data sets adequately well. Future eruption probabilities within a given time interval are
then estimated from the survivor functions. The likelihood that a large plinian eruption will occur at the
CAVA within the next ~100 years is 5-8 %, and the 50 % probability is reached within ~1300 years.
These results are nearly identical for a felsic plinian eruption or an eruption of any composition. Mafic
plinian eruptions are less likely to occur, their probability to happen within ~100 years amounts to 1 %,
while the 50 % and 100 % probability is reached in ~6,000 and ~50,000 years, respectively.
Compared to the felsic plinian eruptions, this latter result may seem relatively reassuring – but in the
context of the worldwide record, in which plinian eruptions of mafic compositions are extremely scarce
and still considered exotic, it is a high probability. As an unusually common phenomenon at the
CAVA, we emphasise the importance to adequately consider mafic plinian eruptions in the course of
comprehensive volcanic hazard assessment.

Document Type: Conference or Workshop Item (Talk)
Keywords: Geodynamics
Research affiliation: OceanRep > SFB 574 > C4
OceanRep > SFB 574 > C2
OceanRep > SFB 574
OceanRep > SFB 574 > A2
Kiel University
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS Magmatic and Hydrothermal Systems
Related URLs:
Date Deposited: 21 Sep 2012 10:28
Last Modified: 21 Sep 2012 10:28
URI: http://oceanrep.geomar.de/id/eprint/15325

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