Three-dimensional P-wave velocity structure on the shallow part of the Central Costa Rican Pacific margin from Local Earthquake Tomography using off- and onshore networks.

Arroyo, Ivonne Gabriela, Husen, S., Flueh, Ernst R., Gossler, J., Kissling, E. and Alvarado, G. E. (2009) Three-dimensional P-wave velocity structure on the shallow part of the Central Costa Rican Pacific margin from Local Earthquake Tomography using off- and onshore networks. Open Access Geophysical Journal International . DOI 10.1111/j.1365-246X.2009.04342.x.

[img]
Preview
Text
771_Arroyo_2009_ThreedimensionalPwaveVelocityStructureOn_Artzeit_pubid12312.pdf - Published Version

Download (2267Kb)
[img] Archive
179-2-827_Supplementary_Data.zip - Supplemental Material

Download (1101Kb)

Supplementary data:

Abstract

The Central Costa Rican Pacific margin is characterized by a high-seismicity rate, coincident with the subduction of rough-relief ocean floor and has generated earthquakes with magnitude up to seven in the past. We inverted selected P-wave traveltimes from earthquakes recorded by a combined on- and offshore seismological array deployed during 6 months in the area, simultaneously determining hypocentres and the 3-D tomographic velocity structure on the shallow part of the subduction zone (<70 km). The results reflect the complexity associated to subduction of ocean-floor morphology and the transition from normal to thickened subducting oceanic crust. The subducting slab is imaged as a high-velocity perturbation with a band of low velocities (LVB) on top encompassing the intraslab seismicity deeper than ∼30 km. The LVB is locally thickened by the presence of at least two subducted seamounts beneath the margin wedge. There is a general eastward widening of the LVB over a relatively short distance, closely coinciding with the onset of an inverted forearc basin onshore and the appearance of an aseismic low-velocity anomaly beneath the inner forearc. The latter coincides spatially with an area of the subaerial forearc where differential uplift of blocks has been described, suggesting tectonic underplating of eroded material against the base of the upper plate crust. Alternatively, the low velocities could be induced by an accumulation of upward migrating fluids. Other observed velocity perturbations are attributed to several processes taking place at different depths, such as slab hydration through outer rise faulting, tectonic erosion and slab dehydration.

Document Type: Article
Keywords: Seismic tomography; Subduction zone processes; Continental margins: convergent; Crustal structure
Research affiliation: OceanRep > SFB 574
OceanRep > SFB 574 > A2
OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1111/j.1365-246X.2009.04342.x
ISSN: 0956-540X
Projects: Future Ocean, SFB574
Contribution Number:
ProjectNumber
SFB 574155
Expeditions/Models/Experiments:
Date Deposited: 26 Oct 2009 09:27
Last Modified: 13 Jul 2018 11:47
URI: http://oceanrep.geomar.de/id/eprint/1782

Actions (login required)

View Item View Item

Document Downloads

More statistics for this item...