Publication Date:
2012-02-03
Description:
An edited version of this paper was published by AGU. Copyright (2010) American Geophysical Union.
Description:
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:
Published
Description:
L18309
Description:
3.1. Fisica dei terremoti
Description:
3.2. Tettonica attiva
Description:
3.3. Geodinamica e struttura dell'interno della Terra
Description:
JCR Journal
Description:
restricted
Keywords:
oceanic lithospheric mantle
;
focal mechanisms
;
stress tensor inversion
;
Gulf of Cadiz
;
ocean bottom seismometer
;
1755 Lisbon earthquake
;
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
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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