Volcanology and Earthquakes

Volcanoes and earthquakes are different but closely related geological phenomena, most occurring near the boundaries of the Earths network of active tectonic plates. This research theme seeks to understand the relationship between tectonics and volcanism, including the volcanism of active continental margins, where plate subduction is occurring today. It uses a wide variety of seismic and electromagnetic imaging tools and is important in hazard mitigation. Highly mobile seismic and electromagnetic networks are used to monitor magmatic and related seismic activity in real-time over volcano seismic sources. Geophysical imaging tools are used to analyse the data to understand the underlying physical processes.

Ongoing research and monitoring at DIAS comprise the following:

It’s location on the mid-Atlantic ridge makes Iceland tectonically and volcanologically very active. The big impact on central Europe of the comparable small eruption of Eyjafjallajökull in 2010 triggered the genesis of the EU funded project FutureVolc. During the project the instrument network in Iceland was densified and multidisciplinary collaborations aimed to mitigate effect of eruptions by establishing an early warning system. Target volcanoes include Hekla volcano with repose times of 10 years and its latest eruption in 2000, Grímsvötn volcano with eruptions in e.g. 1998, 2004 and 2011 and Bárðarbunga volcano with an eruption within FutureVolc in 2014/15. The eruption forecasting studies at DIAS focus on microseismicity and tremor.

Near real time data processing of seismic array data

As part of the Futurevolc project we developed a data processing environment that processes in near real time the data streaming into DIAS from the two clusters (arrays) of seismometers installed in Iceland. The clustering of the seismometers allows for the calculation of the back azimuth (BAZ), i.e. the direction from where seismic waves arrive at the arrays. This is especially useful for tremor signals because they are emergent signals unlike earthquakes that have well defined phase onsets. In addition array analysis results in slowness values which can be used to infer the depth and distance to seismic tremor sources. The near real time results of BAZ and slowness can help to discriminate between different tremor mechanisms which is crucial in eruption forecasting.

The output of the near real time data processing can be accessed at osas.dias.ie. Our Iceland fieldwork and the seismic data streams are featured in this video which was produced before the research group moved from UCD to DIAS: For any questions regarding the near real time data processing please contact Martin Möllhoff, martin@dias.ie.

Stress sensitivity of a volcanic edifice (Mt. Teide, Tenerife)

In February 2014 two seismic networks and an active seismic source were installed in Tenerife in order to record background seismic noise and active seismic data. The main goal of the experiment is to investigate the stress sensitivity of volcanic rock as well as what factors are stressing the material. Therefore changes in seismic wave velocity are monitored in the active seismic data. The second outcome of the project is to look at the changes in seismic wave velocity tracked with background seismic noise compared to those seen in the active seismic data.