Monday, April 24, 2017

Science & Technology: Research Indicates that Migration of Magma is Heavily Influenced by Surface Loading

An Improved Model of How Magma Moves Through the Crust (EOS)

Volcanic eruptions of basalt are fed by intrusions of magma, called dikes, which advance through Earth’s crust for a few hours or days before reaching the surface. Although many never make it that far, those that do can pose a serious threat to people and infrastructure, so forecasting when and where a dike will erupt is important to assessing volcanic hazards.

However, the migration of magma below a volcano is complex, and its simulation is numerically demanding, meaning that efforts to model dike propagation have so far been limited to models that can quantify either a dike’s velocity or its trajectory but not both simultaneously. To overcome this limitation, Pinel et al. have developed a hybrid numerical model that quantifies both by dividing the simulations into two separate steps, one that calculates a two-dimensional trajectory and a second that runs a one-dimensional propagation model along that path.

The results indicate that the migration of magma is heavily influenced by surface loading—the addition or removal of weight on Earth’s surface—such as that caused by the construction of a volcano or its partial removal via a massive landslide or caldera eruption. The team confirmed previous research that showed that increasing surface load attracts magma while also reducing its velocity, whereas unloading diverts much of the magma.

A two-step model for dynamical dike propagation in two dimensions: Application to the July 2001 Etna eruption - V. Pinel, et al. Journal of Geophysical Research: Solid Earth, 25 February 2017.

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(Thanks to GRC Member Marcelo Lippmann, Staff Scientist (retired) at Lawrence Berkeley National Laboratory for the submission.)