Seismicity of the Caribbean‐Nazca Boundary: Constraints on microplate tectonics of the Panama region

Abstract

There are at least three kinds of models that have been used to explain plate motions and boundaries in the Panama region. These models suggest that the major Caribbean‐Nazca boundary is (1) a thrust fault along which the Panama Deformed Belt has developed, (2) a left‐lateral strike‐slip fault along the southern margin of Panama, or (3) a diffuse array of mostly thrust faults which cause internal deformation to occur throughout Panama. In this paper, we use joint epicenter location methods to obtain improved locations for earthquakes that occurred in this region between 1964 and 1985 and we use waveform modeling to obtain more precise depths for five events. Hypocenters of 13 events beneath the Panama Deformed Belt suggest that overthrusting of Panama upon the Caribbean plate causes active deformation which supports model 1 but does not rule out models 2 and 3. The nature of seismic faulting along the Panama Deformed Belt is complex and supports the premise that slow north‐south convergence loads the cold thick Caribbean lithosphere and causes it to fail seismically. Epicenters of 64 events along the Panama Fracture Zone indicate that this north–south trending rightlateral transform fault is splayed north of 6°N. Overall, the seismicity throughout suggests that the Panama arc can be treated as a microplate, in accordance with models 1 or 2. Similarly, a possible second microplate may exist south of Panama, but if so it does not affect regional plate motions significantly. The strongest evidence for model 3 occurs in the easternmost and westernmost portions of Panama, where the diffuse seismicity prevents us from resolving specific microplate triple‐junction boundaries.

Discovery of Lower Cretaceous synmetamorphic thrust tectonics in French Lesser Antilles (La Désirade Island, Guadeloupe): Implications for Caribbean geodynamics

“…To the north, the Caribbean plate is bounded by the Oriental and Septentrional faults and the Puerto Rico trench; while to the south the Caribbean plate is bounded by a dextral strike-slip fault zone, the El Pilar-Central Range fault zone [Jordan, 1975;Adamek et al, 1988;Holcombe et al, 1990;Mascle and Letouzey, 1990;Pindell and Barrett, 1990;Heubeck and Mann, 1991;Mann et al, 1995;Flinch et al, 1999;Weber et al, 2001].…”

The Geology of the Darien, Panama, and the late Miocene-Pliocene collision of the Panama arc with northwestern South America

“…They are conelated with the formation of a postcollision Panama microplate (Fig. 1) that was detached from the Caribbean plate in the north by the convergent North Panama deformed belt (Adamek et al, 1988) and from the Nazca plate to the south Geological Society of America Bulletin, November/December 2004 1341 by the South Panama deformed belt (Mann and Kolarsky, 1995 (Mann and Kolarsky, 1995). Furthermore, Kellogg and Vega (1995) and Trenkamp et al (2002), using global positioning system measurements, have indicated that the Panama microplate is now acting as a rigid indenter with respect to South America.…”

Sismicidad en Costa Rica durante el 2015

“…Esto incluye los sismos superficiales (< 30 km) ocurridos dentro de la placa Caribe y la microplaca de Panamá y en las fallas del Cinturón Deformado del Norte de Panamá (e.g. Adamek et al, 1988) y Cinturón Deformado del Centro de Costa Rica (e.g. Marshall et al, 2000).…”