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Interseismic Strain Accumulation near Lisbon (Portugal) from Space Geodesy
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  • João F.B.D. Fonseca,
  • Mimmo Palano,
  • Ana Paula Falcão,
  • Alexis Hrysiewicz,
  • Jose Fernandez
João F.B.D. Fonseca
Instituto Superior Técnico

Corresponding Author:jfonseca@ist.utl.pt

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Mimmo Palano
Istituto Nazionale di Geofisica e Vulcanologia
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Ana Paula Falcão
CERIS, Department of Civil Engineering, Architecture and Georesources, Instituto Superior Técnico, Universidade de Lisboa
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Alexis Hrysiewicz
UCD School of Earth Sciences
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Jose Fernandez
Instituto de Geociencias (CSIC, UCM)
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The Lisbon Metropolitan Area (LMA, Portugal) has been affected by several destructive earthquakes nucleating both along the offshore Africa-Eurasia plate boundary and on onshore inherited intraplate faults. Using a dense GNSS dataset coupled with PSInSAR analysis, we provide new evidence of sinistral simple shear driven by a NNE-SSW first-order tectonic lineament. PSInSAR vertical velocities corroborate the GNSS strain-rate field, showing uplift/subsidence where the GNSS data indicate contraction/extension. We suggest the presence of a small block to the W of Lisbon moving independently towards the SW with a relative velocity of 0.96±0.20 mm/yr, whose boundaries are part of a complex and as yet poorly constrained strike-slip fault system, possibly rooting at depth into a simpler basement fault. Comparison between geodetic and seismic moment-rates indicates a high seismic coupling. We show that the contribution of intraplate faults to the seismic hazard in the LMA may be more important than currently assumed.
28 Dec 2021Published in Geophysical Research Letters volume 48 issue 24. 10.1029/2021GL096862