A new seismically constrained subduction interface model for Central America

Abstract

We provide a detailed, seismically defined three-dimensional model for the subducting plate interface along the Middle America Trench between northern Nicaragua and southern Costa Rica. The model uses data from a weighted catalog of about 30,000 earthquake hypocenters compiled from nine catalogs to constrain the interface through a process we term the "maximum seismicity method." The method determines the average position of the largest cluster of microseismicity beneath an a priori functional surface above the interface. This technique is applied to all seismicity above 40 km depth, the approximate intersection of the hanging wall Mohorovičić discontinuity, where seismicity likely lies along the plate interface. Below this depth, an envelope above 90% of seismicity approximates the slab surface. Because of station proximity to the interface, this model provides highest precision along the interface beneath the Nicoya Peninsula of Costa Rica, an area where marked geometric changes coincide with crustal transitions and topography observed seaward of the trench. The new interface is useful for a number of geophysical studies that aim to understand subduction zone earthquake behavior and geodynamic and tectonic development of convergent plate boundaries.

Temperature and Gas/Brine Content Affect Seismogenic Potential of Simulated Fault Gouges Derived From Groningen Gas Field Caprock

“…By contrast, brinesaturated samples showed stable velocity-strengthening behavior at temperatures of 50-100°C (Figure 3a), transitioning to velocity-weakening slip at temperatures ≥120°C, or perhaps lower at sliding velocities below the minimum of 0.1 μm/s investigated here (Figure 3b). A similar transition was observed in previous experiments on fluid-saturated fault gouges composed of calcite, anhydrite, or dolomite [Chen et al, 2015;Pluymakers, Samuelson, et al, 2014Scuderi et al, 2013;Verberne et al, 2013], pointing to the importance of chemically assisted, thermally activated mechanism(s) in controlling slip stability for these materials.…”

Detailed spatiotemporal evolution of microseismicity and repeating earthquakes following the 2012 Mw 7.6 Nicoya earthquake

“…The smoother and colder Cocos plate originating from the East Pacific Rise subducts beneath the Peninsula to the north, while the rougher (with many seamounts) and warmer seafloor created at Cocos‐Nazca Spreading center converges with the Caribbean plate to the south with an average rate of 82 mm/yr in the N20°E direction (Figure a) [ DeMets et al ., ]. This is consistent with the along‐strike variation in the updip limit of the seismogenic zone and strong variations in the megathrust interface structure [ Newman et al ., ; Kyriakopoulos et al ., ], as well as an along‐strike variation in the temperature profile of the incoming oceanic plate [ Harris and Wang ; Hutnak et al ., ].…”

“…(a) Seismic network (triangles) and earthquake catalog using SimulPS (blue circles) [ Walter et al ., ], and TomoDD (red circles), following the methodology and model described in Kyriakopoulos et al . []. Inset shows the regional tectonic environment including Cocos plate subduction beneath the Caribbean plate at about 82 ± 2 mm/yr near Nicoya [ Demets et al ., ].…”

“…The geodetic slip models both use the seismically defined 3‐D slab structure of Kyriakopoulos et al . [].…”

“…Kyriakopoulos et al . [] derived a new structural model for the subduction zone interface along the Middle America Trench. This plate geometry model was further used to reevaluate the interseismic locking and coseismic slip [ Kyriakopoulos and Newman , ] and image afterslip both updip of the dominant coseismic slip area and downdip to deep slow‐slip events previously identified [ Hobbs et al ., ].…”