Applying Fractal Dimensions and Energy-Budget Analysis to Characterize Fracturing Processes During Magma Migration and Eruption: 2011–2012 El Hierro (Canary Islands) Submarine Eruption

摘要

The impossibility of observing magma migration inside the crust obliges us toudrely on geophysical data and mathematical modelling to interpret precursors and to forecastudvolcanic eruptions. Of the geophysical signals that may be recorded before and during anuderuption, deformation and seismicity are two of the most relevant as they are directlyudrelated to its dynamic. The final phase of the unrest episode that preceded the 2011–2012uderuption on El Hierro (Canary Islands) was characterized by local and accelerated deformationudand seismic energy release indicating an increasing fracturing and a migration ofudthe magma. Application of time varying fractal analysis to the seismic data and theudcharacterization of the seismicity pattern and the strain and the stress rates allow us toudidentify different stages in the source mechanism and to infer the geometry of the path usedudby the magma and associated fluids to reach the Earth’s surface. The results obtainedudillustrate the relevance of such studies to understanding volcanic unrest and the causes thatudgovern the initiation of volcanic eruptions.