Interseismic Strain Accumulation Near Lisbon (Portugal) From Space Geodesy

Abstract

The Lisbon Metropolitan Area, 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 qualitatively the GNSS strain‐rate field, showing uplift/subsidence where the GNSS data indicate contraction/extension. We propose the presence of a small block to the W of Lisbon moving independently toward 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 is more important than currently assumed.

LADSDIn: LiCSAR-Based Anomaly Detector of Seismic Deformation in InSAR

“…Sentinel-1 acquires up to 2000 SAR images daily, with a data capacity of even 10 TB [19], [20]. In this context, more and more scholars are using MTInSAR technology and Sentienl-1 data to carry out high-precision seismic deformation studies [21], [22], [23]. Due to the extensive range of ground deformation information, good continuity, and high deformation accuracy obtained by MTInSAR technology, the results of fault geometry parameter inversion and sliding distribution inversion are more comprehensive, detailed, and reliable [24], [25].…”