The wet Nicaraguan slab
نویسندگان
چکیده
[1] Nicaraguan volcanoes show globally high concentrations of geochemical tracers from dehydration of subducting crust, which may reflect a slab with unusually high amounts of H2O. To test this possibility, we measure seismic velocities at the top of the subducted plate and compare them with predictions for hydrated mafic rocks. Regional seismic P waves for intraslab events at 100–150 km depth show a high-frequency late arrival, apparently trapped in a low-velocity waveguide 2.5–6 km thick at the top of the downgoing plate, 14.5 ± 2.2% slower than surrounding mantle. The velocities can be explained by 5 wt % H2O in the subducted crust, 2–3 times the hydration inferred for other slabs by similar methods. This interpretation implies extensive hydration of the Cocos Plate off Nicaragua, perhaps enhanced by up-dip fluid flow within the slab at >100 km depth.
منابع مشابه
Wet Slab Instability at the Arapahoe Basin Ski Area
Empirical evidence gathered at the onset of ablation on a ski slope where a wet slab avalanche claimed the life of a skier indicates a chance of snowpack fracture. Wetting fronts which fully penetrate the basal layer of depth hoar in response to the first episode of excessive diurnal melt result in a softening of ice-to-ice contact points and a significant change in cup-shaped ice particle geom...
متن کاملDesign of Spectrometers and Polarization Splitters Using Adiabatically Connected Slab Waveguides
The design of fully integrated prism spectrometers and polarization splitters in adiabatically connected slab waveguides with two different thicknesses, using principles of geometrical optics, is presented. In addition, the design of mirrors to connect these devices to input and output waveguides is discussed. The proposed structures will be fabricated, using two wet-etching steps, in a Si3N4 l...
متن کاملCurrent and future heat stress in Nicaraguan work places under a changing climate.
While climate change continues to increase ambient temperatures, the resulting heat stress exposure to workers in non-climate controlled settings is not well characterized, particularly in low and middle income countries. This preliminary report describes current heat stress in Nicaraguan work places and estimates occupational heat stress in 2050. From over 400 measurements of heat exposure usi...
متن کاملDo You See What I Mean? Corticospinal Excitability During Observation of Culture-Specific Gestures
People all over the world use their hands to communicate expressively. Autonomous gestures, also known as emblems, are highly social in nature, and convey conventionalized meaning without accompanying speech. To study the neural bases of cross-cultural social communication, we used single pulse transcranial magnetic stimulation (TMS) to measure corticospinal excitability (CSE) during observatio...
متن کاملDosimetric Characteristics of Transparent Bolus for External Beam Radiotherapy
Introduction: In radiotherapy, the bolus is often used while treating the tumor under the uneven surfaces of the patients for correcting the anatomical irregularities and increasing skin dose. Wet cotton and wet gauze are still used in developing countries, since the use of wet cotton and wet gauze has certain disadvantages, there is a need for transparent bolus which ...
متن کامل