The Al Hoceima (Morocco) earthquake of 24 February 2004, analysis and interpretation of data from ENVISAT ASAR and SPOT5 validated by ground-based observations

Tahayt, Abdelilah; Feigl, K. L.; Mourabit, Taoufik; Rigo, Alexis; Reilinger, R. E.; McClusky, S.; Fadil, A.; Berthier, Étienne; Dorbath, L.; Serroukh, M.; Gomez, Francisco; Sari, D. Ben

doi:10.1016/j.rse.2008.09.015

Cited by 43 publications

(42 citation statements)

References 32 publications

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“…The distribution of differences in strike has the smallest standard deviation, with most strike differences being smaller than 20°. The greatest difference in strike is 44°, for the model by Tahayt et al [2009] of the 2004 Al Hoceima earthquake, which was also found to be quite different to other InSAR strike estimations, as discussed in section 3.2. A possible explanation for this discrepancy is that this model is a cross fault model, consisting of two subevents separated by about 3 s [e.g., Stich et al , 2005] being quite different from a point source model, such as used in the GCMT approach.…”

Section: Comparisons Between Seismically and Geodetically Derived Earcontrasting

confidence: 70%

“…Differences in strike for a given earthquake are generally smaller than 20° (with a median variability over 18 earthquakes of about 4° and σ = 10°), except for the Al Hoceima 2004 earthquake, for which there is a difference of 44° between the strike determined by Tahayt et al [2009] and that found by Biggs et al [2006] (see Table 3). For the 19 earthquakes in Tables 1–3 with more than one value of fault dip reported, the variability in dip is smaller than 20° (with a median of about 8° and σ = 6°), except for the 2000 Cankiri earthquake, for which there is a difference of 22° between the fault dip determined by Wright [2000] and that obtained by Cakir and Akoglu [2008].…”

Section: Analysis Of the Variability Of Insar Source Models For A Givmentioning

confidence: 97%

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Global compilation of interferometric synthetic aperture radar earthquake source models: 1. Comparisons with seismic catalogs

2011

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[1] While many earthquakes have now been studied using interferometric synthetic aperture radar (InSAR) data, a full assessment of the quality and additional value of InSAR source parameters compared to seismological techniques is still lacking. We compile a catalog of source models obtained using InSAR and estimate the corresponding centroid moment tensor (CMT) parameters; we refer to this compilation as the ICMT archive. We compare source parameters from over 70 InSAR studies of 57 global earthquakes with those in the Global CMT (GCMT), International Seismological Centre (ISC) and Engdahl-Hilst-Buland (EHB) seismic catalogs. We find an overall good agreement between fault strike, dip and rake values in the GCMT and ICMT archives. Likewise, the differences in seismic moment between these two archives are relatively small, and we do not find support for previously suggested trends of InSAR leading to larger moments than seismic data. However, epicentral locations show substantial discrepancies, which are larger for the GCMT (median differences of ∼21 km) than for the EHB and ISC catalogs (median differences of ∼10 km). Since InSAR data have a high spatial resolution, and thus should map epicentral locations accurately, this allows us to obtain a first independent estimate of epicentral location errors in the seismic catalogs. Earthquake depths from InSAR are systematically shallower than those in the EHB catalog, with a median of differences of ∼5 km. While this trend may be partly due to unmodeled crustal complexity, it is also compatible with the observation that the rupture of crustal earthquakes tends to propagate upward in the seismogenic layer.Citation: Weston, J., A. M. G. Ferreira, and G. J. Funning (2011), Global compilation of interferometric synthetic aperture radar earthquake source models: 1. Comparisons with seismic catalogs,

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Section: Comparisons Between Seismically and Geodetically Derived Earcontrasting

confidence: 70%

Section: Analysis Of the Variability Of Insar Source Models For A Givmentioning

confidence: 97%

Global compilation of interferometric synthetic aperture radar earthquake source models: 1. Comparisons with seismic catalogs

2011

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“…1c). Onshore field studies following the 2004 earthquake showed cracks through the Tisirene Flyschs and the Ketama units, with a general orientation of r3 around N40°(A€ ıt Galindo-Zald ıvar et al, 2009;Tahayt et al, 2009). However, no clear primary surface rupture can be observed Biggs et al, 2006).…”

Section: Recent Deformationmentioning

confidence: 99%

Evidence of quaternary transtensional tectonics in the Nekor basin (NE Morocco)

et al. 2016

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International audienceThe geodynamic processes in the western Mediterranean are driven by both deep (mantle) processes such as slab-rollback or delamination, oblique plate convergence and inherited structures. The present-day deformation of the Alboran Sea and in particular the Nekor basin area is linked to these coeval effects. The seismically active Nekor basin is an extensional basin formed in a convergent setting at the eastern part of the Rif Chain whose boundaries extend both onshore and offshore Morocco. We propose a new structural model of the Nekor basin based on high-resolution offshore data compiled from recent seismic reflection profiles, swath bathymetry acquisitions and industrial seismic reflection profiles. The new data set shows that the northern limit of the basin is oriented N49° with right-stepping faults from the Bousekkour–Aghbal fault to the sinistral Bokkoya fault zone. This pattern indicates the presence of an inherited left-lateral basement fault parallel to the major inherited Nekor fault. This fault has been interpreted as a Quaternary active left-lateral transfer fault localized on weak structural discontinuities inherited from the orogenic period. Onshore and offshore active faults enclose a rhombohedral tectonic Nekor Basin. Normal faults oriented N155° offset the most recent Quaternary deposits in the Nekor basin, and indicate the transtensional behaviour of this basin. The geometry of these faults suggests a likely rollover structure and the presence at depth of a crustal detachment. Inactive Plio-Quaternary normal faults to the east of the Ras Tarf promontory and geometries of depocentres seem to indicate the migration of deformation from east to west. The local orientations of horizontal stress directions deduced from normal fault orientations are compatible with the extrusion of the Rifian units and coherent with the westward rollback of the Tethyan slab and the localization of the present-day slab detachment or delamination

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“…We do not use strike, dip and rake values that were fixed in some InSAR studies (see paper 1). As in the comparisons between ICMT and GCMT parameters (see paper 1 and M = −1.621 diagram in Figure 8), there are large differences in strike (greater than 40°) for the 2004 Al Hoceima earthquake between all our solutions and the InSAR solution of Tahayt et al [2009]. Other than that outlier, there is good agreement between the strike values found in our inversions and the ICMT strike values, with the models S20RTS and vHW99 showing the smallest differences, which are similar to those between the GCMT and ICMT solutions.…”

Section: Resultsmentioning

confidence: 51%

Global compilation of interferometric synthetic aperture radar earthquake source models: 2. Effects of 3-D Earth structure

Ferreira¹,

Weston²,

Funning³

2011

J. Geophys. Res.

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[1] We carry out long-period surface wave centroid moment tensor (CMT) inversions using various global tomographic models and two different forward modeling techniques for 32 large earthquakes previously studied using interferometric synthetic aperture radar (InSAR) data. Since InSAR methods provide an alternative and independent way of locating and characterizing shallow continental earthquakes, comparisons of our source parameters with those from InSAR are a novel way to assess limitations in the InSAR models as well as the effects of inaccurate wave propagation formulations and/or 3-D Earth structure on earthquake source determinations. We show that comparing InSAR results with our seismic solutions is valuable to identify inaccuracies in the earthquake slip distribution retrieved using InSAR. Moreover, we find that using more accurate formulations, together with the best fitting Earth models, substantially reduces biases and differences between moment magnitude and fault strike determined using InSAR and seismic data. As expected for long-period surface wave source inversions for shallow earthquakes, the fault dip and rake angles are difficult to constrain, but we show that when using the best fitting Earth models, differences to InSAR estimates are reduced. Moreover, spurious deviations from a pure double-couple earthquake mechanism are on average smaller for the best fitting Earth models and the more accurate formulation of wave propagation. There are large differences between InSAR epicentral locations and those obtained in this study and, on average, no clear improvements to the Global CMT locations are achieved. This suggests that higher-resolution Earth models are necessary to further refine long-period CMT epicentral locations.Citation: Ferreira, A. M. G., J. Weston, and G. J. Funning (2011), Global compilation of interferometric synthetic aperture radar earthquake source models: 2. Effects of 3-D Earth structure,

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The Al Hoceima (Morocco) earthquake of 24 February 2004, analysis and interpretation of data from ENVISAT ASAR and SPOT5 validated by ground-based observations

Cited by 43 publications

References 32 publications

Global compilation of interferometric synthetic aperture radar earthquake source models: 1. Comparisons with seismic catalogs

Global compilation of interferometric synthetic aperture radar earthquake source models: 1. Comparisons with seismic catalogs

Evidence of quaternary transtensional tectonics in the Nekor basin (NE Morocco)

Global compilation of interferometric synthetic aperture radar earthquake source models: 2. Effects of 3-D Earth structure

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