10:45 〜 12:15
[SCG45-P22] Slab diversity and segmentation along the Middle America Trench: a framework for understanding geodynamic processes of subduction
キーワード：Subduction, Geodynamics, Middle America Trench
The Middle America subduction zone is one of the youngest convergent
margins and involves the subduction of the two oceanic plates, Rivera and Cocos
plates, beneath the North American and Caribbean plates. Although along trench
subduction parameters (i.e., plate age and convergence rate) show a relatively smooth
variations, the Rivera and Cocos slabs display a remarkable diversity. The slab
geometry shows unusual contortions in a closed space, including a large segment of
uncommon shallow (depth less than 45 km) flat slab. Although the Middle America
subduction zone is characterized by intense seismic activity, it is also marked by two
large seismic gaps (where no large megathrust earthquakes occurred in more than a century)
whose origin is still elusive. For example, the Guerrero seismic gap is located in the
middle of the flat slab segment, although the incoming oceanic plate does not show
any unusual bathymetric feature that can be considered the cause of such seismic
discontinuity. To the south, the Tehuantepec seismic gap shows a spatial correlation
with a large oceanic fracture zone, but the relationship between the two is still elusive.
At depth, seismic observations show the existence of several vertical tears as well as
horizontal truncation of the Rivera and Cocos slabs beneath Mexico. On the surface,
volcanism shows a rather discontinuous nature, with large gaps, non-common locations
and position (i.e., oblique to the trench). The geodynamical nature of processes that
control the formation and evolution of these observed processes is still not well
understood. In this study, we review these processes in the light of up-to-date research
studies and propose a series of research directions and hypotheses to foster future
geodynamical modeling studies. Using the intrinsic predictive nature of numerical
models, we aim to advance our understanding about how this active margin formed
and evolved.
margins and involves the subduction of the two oceanic plates, Rivera and Cocos
plates, beneath the North American and Caribbean plates. Although along trench
subduction parameters (i.e., plate age and convergence rate) show a relatively smooth
variations, the Rivera and Cocos slabs display a remarkable diversity. The slab
geometry shows unusual contortions in a closed space, including a large segment of
uncommon shallow (depth less than 45 km) flat slab. Although the Middle America
subduction zone is characterized by intense seismic activity, it is also marked by two
large seismic gaps (where no large megathrust earthquakes occurred in more than a century)
whose origin is still elusive. For example, the Guerrero seismic gap is located in the
middle of the flat slab segment, although the incoming oceanic plate does not show
any unusual bathymetric feature that can be considered the cause of such seismic
discontinuity. To the south, the Tehuantepec seismic gap shows a spatial correlation
with a large oceanic fracture zone, but the relationship between the two is still elusive.
At depth, seismic observations show the existence of several vertical tears as well as
horizontal truncation of the Rivera and Cocos slabs beneath Mexico. On the surface,
volcanism shows a rather discontinuous nature, with large gaps, non-common locations
and position (i.e., oblique to the trench). The geodynamical nature of processes that
control the formation and evolution of these observed processes is still not well
understood. In this study, we review these processes in the light of up-to-date research
studies and propose a series of research directions and hypotheses to foster future
geodynamical modeling studies. Using the intrinsic predictive nature of numerical
models, we aim to advance our understanding about how this active margin formed
and evolved.