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Forecasting the recurrence rate of volcanic eruptions

Periodic Reporting for period 2 - FEVER (Forecasting the recurrence rate of volcanic eruptions)

Reporting period: 2017-10-01 to 2019-03-31

500 million people live in proximity of volcanoes and eruptions have a significant social and economical impact, thus forecasting the recurrence rate of volcanic eruption remains a great challenge in science. The target of FEVER is to produce a physically based statistical model able to ForEcast the recurrence rate of Volcanic ERuptions both at regional and global scale. What are the physical processes that control the size and frequency of volcanic eruptions at regional and global scale? Using a range of geochemical and statistical techniques FEVER tackles this question.
During the first period we completed all field-sampling campaigns and we started collecting data that will constrain our models. We have completed fieldwork in the three localities of interest for the project (Colorado, Mexico and Lesser Antilles) and we collected sufficient rock samples for the all members of the team to complete their research on this project. All members of the team have been presenting their initial results at various international conferences.
In a first scientific article we collected data on the recurrence rate of large explosive volcanic eruptions for different active volcanic regions. In this contribution we presented a new method to deal with biases in the geological record. Biases include: 1) the rapid erosion of deposits of even relatively large eruptions (e.g. the Pinatubo eruption of 1991 was about 4 times larger than the 1980 eruption of Mt. S. Helens and its deposits have been almost completely removed by abundant rain that falls in the region); 2) the very small number of large eruptions that occurred in the last few hundred years over which the record is rather complete. Both these factor contribute to decrease the statistical significance of geological data. Thus, to obtain reliable data on which to work, we must first remove or mitigate the effect of these biases on our datasets. After applying our new method to de-bias the data we were able to show that the recurrence rate of volcanic eruption of different magnitudes (mass of erupted magma in a single explosive event) varies from one region to another. For instance in Japan eruption of smaller magnitude are much more abundant than in South America where the proportion of larger eruptions is higher. This discovery is important for two main reason: 1) To date the global recurrence rate of volcanic eruptions was used to make inferences on the recurrence rate of volcanic eruptions at the regional scale, which we can now show was not correct and resulted in incorrect estimates of the probability of an eruption of a given magnitude to occur in a specific time range. 2) We can now better estimate the characteristic recurrence rate of volcanic eruptions at regional and global scale. As a continuation of this research line, we have just completed a scientific article in which we investigate the link between the recurrence rate of volcanic eruptions and tectonics at convergent plate margins, where most of the explosive eruptions occur.
To establish a significant connection between the recurrence rate of volcanic eruptions and the physics of magmatic processes occurring at inaccessible depth, which is the main target of FEVER, we started combining numerical modeling and geochemistry. The analyses of volcanic rocks we performed for volcano Nevado de Toluca in Mexico, Southern Rocky Mountains and the Lesser Antilles, in combination with existing data show that while some volcanoes erupt magmas with a wide variety of compositions, other erupts magmas of very monotonous composition. We used thermal modeling to show that this difference is inextricably linked to the average magma flux and the periodicity of magma injection in magma reservoirs associated with volcanoes. This is particularly important for the success of FEVER because we can use measurable parameters at the surface to quantify processes, which have been so far difficult to constrain because they occur at inaccessible depth of tens of kilometers.
In two different scientific articles we show that processes occurring at the surface of our planet and environmental changes can affect the regional recurrence rate of volcanic eruptions. In one of these studies, we show that during ice melting volcanic activity increases not only because of the decrease of ice load at the surface but also because of the associated glacial erosion. In another we show how the relatively rapid desiccation of the Mediterranean about 5.5 million years ago, caused an increase of volcanism in the circum-Mediterranean reg
"The frequency at which volcanic eruptions occur is inversely proportional to their size but only recently we contributed to identify some of the physical processes controlling this relationship. While this provides a solid base on which to build this project, the lack of data on the distribution of key parameters controlling the recurrence rate of volcanic eruptions, such as the global distribution of the flux of magma from depth, jeopardizes our ability of determining the probability of explosive eruptions of different sizes to occur on Earth in a given time period. Volcanic activity affects directly more than 500 million people living around active volcanoes and produces effects both at the local and the global scale. Thus, ForEcasting the recurrence rate of Volcanic ERuptions remains a challenge of paramount importance for Earth scientists. With FEVER I intend to face this challenge.
With this project, I am building a research group focusing on the construction of physically based statistical models able to quantify the probability of explosive eruptions of different magnitudes to occur at regional and global scale in a defined time-interval. This approach is of paramount importance for the assessment of global volcanic risk and to define the economical impact of volcanic activity on businesses such as aviation, or for administrative decisions related, as an example, to the location of power plants in volcanic regions such as Europe, the United States or Japan.
By the end of the project we expect that the collected results and the newly designed model will allow us to estimate the recurrence rate of volcanic eruptions in different regions of our planet and at the global scale. This will be essential for the sustainable development of our society and especially in regions at elevated volcanic hazard such as Europe and Japan. The results of this project will also be of interest for the airline industry because we will be able to provide estimates of the probability of eruptions such as the 2010 eruption of Eyjafjallajokull to occur in the future.

In a manuscript currently in review in Earth and Planetary Science Letters we address the links between global tectonic and volcanism. This contribution goes toward the final targets of the project because it contributes to identify which large-scale geodynamic processes influence the recurrence rate of eruptions of different magnitudes. This publication marks an important step for our research as we started approaching the study of volcanic eruptions using a data-focused approach that takes advantage of the power of Bayesian Networks to investigate highly multidimensional data sets. While this was not initially consider as part of the proposal, we will make more extensive use of this approach until the end of the project to put in context the large amount of data we are collecting for volcanic systems showing different characteristics. This approach will certainly inspire future project targeting the understanding of the ""behavior of volcanic systems""."
Distribution of large explosive eruptions in the last 12000 years. Circle diameter = eruption size