Periodic Reporting for period 1 - GEOMED (Geodynamics of the Central Mediterranean: A multidisciplinary investigation of the Sicily Channel region)
Reporting period: 2019-09-01 to 2021-08-31
This project aims to understand the evolution of plate margins when multiple tectonic processes (e.g. plate convergence, subduction, and backarc extension) interact within a small area (e.g. the Calabrian arc in the Central Mediterranean). These margins are prone to catastrophic earthquakes, tsunami, and volcanic eruptions, which are all linked to long-term dynamic tectonic processes. Various models explain the evolution of these plate margins, however, they lack detail on the extension and rifting that takes place along the arcs. The earthquakes in these areas have a strong dependence on their location along the arc, and hence in any effort aimed at mitigating seismic risk, it is crucial to have a complete understanding of how plate tectonics work when multiple tectonic processes act.
GEOMED is a multidisciplinary geophysical and geodynamic investigation of seismic data with additional physical constraints and analogue modelling to improve our understanding of this important aspect of plate tectonics. This is accomplished by studying the Calabrian Arc, with special attention to the Sicily Channel Rift Zone (SCRZ). Through GEOMED, the extent of the shallow extension across the Tyrrhenian Sea and the Sicily Channel is mapped in high resolution. Beneath the SCRZ, the lithosphere is thin and underlain by a low shear velocity zone, and the asthenosphere is characterised by strong negative radial anisotropy. The low shear velocities, which are a proxy for high temperatures, and the radial anisotropy indicate vertical flow in the mantle. The results advocate for an active upwelling and rifting process. It is also discovered that the SCRZ has far higher seismicity than previously thought and that the activity of the marine faults extends farther towards the southeast. Unlike previous believe, there is no evidence of deep earthquakes in this region.
The study contributes to the mitigation of seismic risk by improving the seismic hazard assessment of the countries affected in the region. Some of these places are highly inhabited areas, home to millions of citizens, a destination for millions of tourists, and have strong commercial activity offshore.
GEOMED is a multidisciplinary geophysical and geodynamic investigation of seismic data with additional physical constraints and analogue modelling to improve our understanding of this important aspect of plate tectonics. This is accomplished by studying the Calabrian Arc, with special attention to the Sicily Channel Rift Zone (SCRZ). Through GEOMED, the extent of the shallow extension across the Tyrrhenian Sea and the Sicily Channel is mapped in high resolution. Beneath the SCRZ, the lithosphere is thin and underlain by a low shear velocity zone, and the asthenosphere is characterised by strong negative radial anisotropy. The low shear velocities, which are a proxy for high temperatures, and the radial anisotropy indicate vertical flow in the mantle. The results advocate for an active upwelling and rifting process. It is also discovered that the SCRZ has far higher seismicity than previously thought and that the activity of the marine faults extends farther towards the southeast. Unlike previous believe, there is no evidence of deep earthquakes in this region.
The study contributes to the mitigation of seismic risk by improving the seismic hazard assessment of the countries affected in the region. Some of these places are highly inhabited areas, home to millions of citizens, a destination for millions of tourists, and have strong commercial activity offshore.
GEOMED was divided into 5 Work Packages (WP). In WP1, seismic data from various countries, including Italy, Tunisia, Malta, and Libya, were compiled into one dataset. Seismic imaging techniques that invert ambient seismic noise to shear-velocity with depth were used to generate a 3-dimensional model. The regional seismic structure below the Central Mediterranean, from Sardinia to Calabria encompassing the Tyrrhenian Sea, and from the Central Apennine to north Africa encompassing the Sicily Channel was modelled in high resolution. The model also shows the internal dynamics of the lithosphere and uppermost mantle of the entire region, highlighting the extent of lithosphere extension across the Tyrrhenian Sea and the Sicily Channel. It was discovered that the lithosphere across the Sicily Channel is thin and that the rifting process of the SCRZ is underlain by vertical flow in the mantle. In WP2, weak earthquakes recorded on only one seismic station at the south-eastern end of the SCRZ were reprocessed carefully. A new earthquake catalogue for the Sicily Channel was compiled. It was found that the south-eastern area of the Channel is highly seismic and that the seismicity aligns with the bathymetry. The new catalogue highlights the extent of the active marine faults of the SCRZ. In WP3, the results from WP1 and WP2 were incorporated into a regional geodynamic model. This model integrates different physical properties observed from the surface with the newly inferred seismic model to understand the nature and role of multiple tectonic processes.
WP4 covered the dissemination and communication of the project. A website dedicated to GEOMED was set up to share information about the project with the public and the scientific community. GEOMED was featured in numerous local and international seminars and conferences as part of the dissemination and exploitation. And, as part of the planned deliverables, results were submitted and published in open access journals. A strong effort was made to communicate the project activities to different target audiences through multi-lingual public engagement. Because many countries faced national lockdowns and cancellation of public events due to the COVID-19 pandemic, GEOMED was instead featured on many online media platforms. A graphic animation explaining GEOMED was produced and promoted in English and Italian.
WP5 dealt with project management. This package includes financial management, risk contingency management, training and career development of the research fellow, data management, progress monitoring and risk management. The pandemic brought unforeseen challenges to the project, but most of the work was executed as scheduled, thanks to careful planning and continuous risk assessment.
WP4 covered the dissemination and communication of the project. A website dedicated to GEOMED was set up to share information about the project with the public and the scientific community. GEOMED was featured in numerous local and international seminars and conferences as part of the dissemination and exploitation. And, as part of the planned deliverables, results were submitted and published in open access journals. A strong effort was made to communicate the project activities to different target audiences through multi-lingual public engagement. Because many countries faced national lockdowns and cancellation of public events due to the COVID-19 pandemic, GEOMED was instead featured on many online media platforms. A graphic animation explaining GEOMED was produced and promoted in English and Italian.
WP5 dealt with project management. This package includes financial management, risk contingency management, training and career development of the research fellow, data management, progress monitoring and risk management. The pandemic brought unforeseen challenges to the project, but most of the work was executed as scheduled, thanks to careful planning and continuous risk assessment.
The results from GEOMED present a new, better, seismically derived tectonic model for the Central Mediterranean. Until GEOMED, this area was studied in fragments bounded by national territories, whereas now, the encompassing area is studied as an entire region irrespective of national boundaries. The structural model and the related inferred tectonic dynamics provide a new understanding of the region. The earthquake catalogue will be shared with the International Seismological Centre (ISC), responsible for collecting, archiving, processing, and distributing the definitive summary of world seismicity. The ISC data is used extensively by seismologists and geoscientists to compute earthquake risk models. The results contribute towards the European policy objectives mainly towards Europe 2020 European Research Area for Secure Societies by advancing innovation in society at large and among first responders to reduce the loss of human life and reduce environmental, economic, and material damage from natural disasters, including earthquakes volcanic events.