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H2020Individual fellowship2021–2024

SEGMENT · Studying the Effect of Geometrical Features on Megathrust Earthquakes using Natural Observations and Seismotectonic Numerical Models

Horizon 2020 — Marie Skłodowska-Curie Actions

Duration
2021-09-01 → 2024-09-30
EU contribution
€175,572
Participants
1
Scheme
MSCA-IF

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Results in brief

Studying the Effect of Geometrical Features on Megathrust Earthquakes using Natural Observations and Seismotectonic Numerical Models

Half of the world population lives on subduction zones, regions that have hosted the largest earthquakes on Earth. Subduction zones are convergent margins where the downgoing movement of oceanic lithosphere occurs along massive interplate thrust faults, also called subduction megathrusts. Large earthquakes and the tsunamis they often generate, cause extensive human losses and severe economic and property damage in densely populated areas. It is therefore crucial to gain a thorough understanding of the spatial and temporal occurrence of earthquakes along the subduction megathrust. A common understanding of the subduction interface is that it is paved with patches with different frictional properties, thereby causing heterogeneity in terms of seismogenic behaviour. Subducting geometrical features, such as seamounts and ridges, are thought to play a role in the spatial distribution of these seismic and aseismic regions. Studies in the last decade converged to the notion that large smooth portions of the megathrust are more prone to host large earthquakes, but seafloor features been related to both seismic and aseismic behaviour. A thorough understanding of the relationship between these features and the segmentation of the interface into seismic and aseismic regions is needed to accurately assess seismic hazard and forecast where and when we can expect megathrust earthquakes. SEGMENT aimed to understand and quantify the relationship between geometrical features and the spatial and temporal segmentation of the megathrust by combining quantified seafloor roughness and advanced geodetic inversion techniques with novel seismotectonic numerical models.

Data: CORDIS, © European Union

Project objective

Earthquakes and associated tsunamis cause extensive human and economic losses and severe property damage in densely populated areas. The largest earthquakes occur in subduction zones, regions where one tectonic plate dives below another. To better prepare society, it is crucial to understand what controls the spatial and temporal occurrence of those largest earthquakes. Geometrical features on the seafloor that subduct with the downgoing plate, like seamounts and ridges, are thought to play an important role by segmenting the plate interface into seismic and aseismic regions. However, a physical and quantitative understanding of the role of geometrical features on the occurrence of earthquakes remains elusive due to limitations in observation time and space, as well as in modelling of crustal deformation mechanisms in 2D and 3D. SEGMENT will overcome these limitations through integrating the latest advanced forward and inverse modelling tools to study how and how much subducting geometrical features influence subduction earthquakes. Seismotectonic numerical models will be combined with probabilistic natural observations from geodesy and seafloor roughness to optimally extract complementary information and quantify elusive links. As these necessary tools are only now ready for exploration this proposal is highly timely. It will address important open questions related to how geometrical features influence the deformation at and around the plate interface, how this varies throughout multiple earthquake cycles and their role in rupture nucleation, propagation and arrest. SEGMENT thus places me in the position to make a breakthrough in a long-standing debate through providing a novel conceptual model describing the relationship between geometrical features along the subduction interface and the occurrence of earthquakes. This is crucial for improving seismic hazard assessment and our comprehension of subduction dynamics at all timescales.

Original text from CORDIS.

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Data: CORDIS, © European Union