A recent earthquake in Spain has revealed a fascinating underground secret: an overturned oceanic slab. Researchers studying seismic wave anomalies from a 2010 earthquake have discovered this rare occurrence, shedding light on the tectonic structure of the western Mediterranean basin.
The seismic records from the earthquake in Spain depicted the oceanic slab rapidly descending into the Earth’s mantle and flipping over. This overturned slab could potentially explain the deep earthquakes in southern Spain. The presence of hydrous magnesium silicates in the slab indicates a relatively cold slab, likely due to a significant amount of water carried down to the mantle transition zone.
The research team focused on the Rif-Betic-Alboran region, where the Betic and Rif mountain ranges converge along with the Alboran Sea basin. By analyzing the waveforms recorded from the earthquake, they discovered a thin low-velocity layer at the base of the slab, extending to about 600 km depth. This layer of hydrous magnesium silicates could be responsible for triggering deep-focus earthquakes through dehydration embrittlement.
The researchers found that the overturned Alboran slab contradicts the traditional slab model, where the low-velocity layer sits on top of the slab. This discovery could offer insights into the speed of subduction in the region, with implications for other seismic hotspots globally.
As researchers explore the implications of their study, they suggest extending the investigation to other regions with deep earthquakes. The study, published in the journal The Seismic Record, provides a detailed analysis of the seismic data and offers a new perspective on the tectonic processes at play in the western Mediterranean basin.
