Seismology

The movement and interaction of tectonic plates gives rise to many of the Earth's most dramatic and hazardous geologic features. In the Pacific Northwest, the processes accompanying the creation of the oceanic Juan de Fuca plate and its eventual subduction beneath North America result in mountain building, damaging earthquakes and explosive volcanism. Seismology is one of the principal tools for understanding the causes of such geologic hazards, as well as the processes responsible for the formation, evolution, interaction, and destruction of tectonic plates. The Regional OOI cabled system is particularly suitable for such studies since the Juan de Fuca plate incorporates a remarkable array of plate tectonic features within a relatively small area, including all major types of oceanic plate boundary and a continent-ocean convergent margin capable of destructive earthquakes.

Juan de Fuca Ridge

On the Juan de Fuca Ridge, earthquake recordings will be an integral part of multidisciplinary observatories that will characterize the volcanic, tectonic and hydrothermal processes that form the ocean crust, and the role of mid-ocean ridge volcanoes in supporting novel chemosynthetic communities above and below the seafloor. Seismic monitoring can be used to detect and characterize the diking-eruptive events and fault movements that accommodate the separation of tectonic plates and the formation of new oceanic crust. Small earthquakes in the hydrothermal reaction zone immediately above the crustal magma chamber are likely the result of thermal stresses caused by the interaction of hydrothermal cooling and magmatic heating, and play an important role in creating and maintaining the cracks necessary to support vigorous hydrothermal circulation.

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