Imaging near a Subduction-Transform Edge Propagator Fault with Receiver Functions from the LIPARI Seismic Array, Southern Italy
Abstract
At the southern end of the Calabria-Sicily trench, the lateral termination of subduction is associated with the continual tearing of the lithosphere where a Subduction-Transform-Edge Propagator (STEP) fault allows subduction to continue (Govers & Wortel, 2005). STEPs are unlike traditional transform plate boundaries and may present zones of non-uniform deformation, characterized by a scarcity of strike-slip earthquakes (Bilich et al., 2001). Once established, they are thought to be stable features that continue to propagate through the plate in the opposite direction to subduction, with lateral variations in lithospheric strength in front of the STEP redirecting its path. Despite being found in multiple locations around the world, these features are not straightforward to characterize because of the difficulty accessing these locations and the limited records of seismicity.
Volcanism in STEP regions is distinct from typical arc volcanism and along with hydrothermal activity, these processes have been underexplored in the past. Still understanding the interplay between volcanism and tectonic deformation is key to understanding STEP propagation. To achieve this, we deployed a dense seismic array of 48 FairfieldNodal ZLand 3-component nodes in the proximity of the Tindari-Letojanni STEP fault on Lipari island, an active volcano located near the southern edge of the Calabria-Sicily trench. The LIPARI array also marks the first time that a dense seismic array has been deployed to investigate a hydrothermal system in the volcanically active Aeolian Islands.Our array recorded continuously for ~30 days (Oct-Nov 2018) with a ~0.1-1.5 km station spacing. We investigate the lithospheric structure by computing receiver functions from 26 teleseismic events (M>5.2) in the 30-90° distance range. Because of our dense station spacing and complete coverage of the island, and also due to the fact that the array recorded multiple events from a wide range of backazimuths, the Moho P-to-s conversion points from the 26 events form a shotgun pattern around Lipari. This may allow us to image a ~20 km x 20 km region around the island that is offshore and includes lithosphere on both sides of the Tindari-Letojanni STEP fault.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.T51H0412P
- Keywords:
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- 4315 Monitoring;
- forecasting;
- prediction;
- NATURAL HAZARDS;
- 7230 Seismicity and tectonics;
- SEISMOLOGY;
- 8170 Subduction zone processes;
- TECTONOPHYSICS;
- 8488 Volcanic hazards and risks;
- VOLCANOLOGY