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http://hdl.handle.net/2122/6417
Authors: | Geissler, W. H.* Matias, L.* Stich, D.* Carrilho, F.* Jokat, W.* Monna, S.* IbenBrahim, A.* Mancilla, F.* Gutscher, M.-A.* Sallarès, V.* Zitellini, N.* |
Title: | Focal mechanisms for sub‐crustal earthquakes in the Gulf of Cadiz from a dense OBS deployment | Journal: | Geophysical Research Letters | Series/Report no.: | / 37 (2010) | Publisher: | American Geophysical Union | Issue Date: | 30-Sep-2010 | DOI: | 10.1029/2010GL044289 | Keywords: | oceanic lithospheric mantle focal mechanisms stress tensor inversion Gulf of Cadiz ocean bottom seismometer 1755 Lisbon earthquake |
Subject Classification: | 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques 04. Solid Earth::04.07. Tectonophysics::04.07.04. Plate boundaries, motion, and tectonics 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress |
Abstract: | An eleven‐month deployment of 25 ocean bottom seismometers provides an unprecedented opportunity to study low‐magnitude local earthquakes in the complex transpressive plate boundary setting of the Gulf of Cadiz, known for the 1755 Lisbon earthquake and tsunami. 36 relocated earthquakes (ML 2.2 to 4.8) concentrate at 40– 60 km depth, near the base of the seismogenic layer in ∼140 Ma old oceanic mantle lithosphere, and roughly align along two perpendicular, NNE‐SSW and WNWESE striking structures. First motion focal mechanisms indicate compressive stress for the cluster close to the northern Horseshoe fault termination which trends perpendicular to plate convergence. Focal mechanisms for the second cluster near the southern termination of the Horseshoe fault indicate a strike‐slip regime, providing evidence for present‐day activity of a dextral shear zone proposed to represent the Eurasia‐Africa plate contact. We hypothesize that regional tectonics is characterized by slip partitioning. | Description: | An edited version of this paper was published by AGU. Copyright (2010) American Geophysical Union. |
Appears in Collections: | Article published / in press |
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