Basili, R.

Grácia, E.

Gómez de La Peña, Laura

Lorito, S.

Maesano, F.

Piatanesi, A.

Ranero, Cesar

Romano, F.

Serra, C.

Volpe, M.

English

OceanRep

Geophysical Research AbstractsVol. 21, EGU2019-13414, 2019EGU General Assembly 2019© Author(s) 2019. CC Attribution 4.0 license.A preliminary evaluation of the tsunamigenic potential of the active faultsat the Alboran Basin (westernmost Mediterranean) based on new seismicdataLaura Gómez de la Peña (1), Eulàlia Gràcia (2), Stefano Lorito (3), Alessio Piatanesi (3), Roberto Basili (3),Francesco E. Maesano (3), Fabrizio Romano (3), Manuela Volpe (3), Cristina S. Serra (2), and César R. Ranero(4)(1) GEOMAR Helmholtz Centre for Ocean Research Kiel, Dynamics of the Ocean Floor, Kiel, Germany(lgomez@geomar.de), (2) Barcelona Center for Subsurface Imaging, Institut de Ciències del Mar, CSIC, Barcelona, Spain, (3)Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy, (4) ICREA at Institut de Ciències del Mar, CSIC, Barcelona, SpainThe Alboran Basin, located in the westernmost Mediterranean, hosts the boundary between the European andAfrican tectonic plates. The deep structure of this basin is poorly constrained by regional tomographic models,and the tsunamigenic potential of individual faults is partly undefined.Modern data acquired in the area during the last 15 years (e.g., active source seismic data from WESTMEDcruise in 2006, EVENT-DEEP cruise in 2010 and TOPOMED cruise in 2011; and passive seismic data fromTOPO-Europe and TOPO-Iberia projects in 2009-2010) are fundamental to constrain the crustal thickness and toimage the sedimentary and tectonic structure of this area. Results of these surveys allowed us to advance in thecharacterization of the main active faults in the Alboran Basin (i.e. Carboneras, Al-Idrissi, Yusuf and AlboranRidge front faults), and to review their tsunamigenic potential.To estimate the possible tsunamigenic potential for each fault, we followed a two-step workflow. First, weanalysed the faults in the area, selecting the potentially most tsunamigenic ones and describing them in detail. Wecreated 3D models of the fault planes, using bathymetric and active and passive seismic data. The dense grid ofmultichannel seismic data, together with the pre-stack depth-migrated sections and a refraction profile showingthe velocity structure across the basin, allowed us to consider for the first time in the area realistic geometry ofthe major faults. Second, we calculated the possible tsunami scenarios for each fault, using our 3D fault planemodels and their simplified rectangular plane version, all with associated seismic parameter estimates. Tsunamisimulations were done with Tsunami-HySEA non-linear shallow water GPU-optimised code developed by theEDANYA Group of the University of Malaga, Spain (de la Asunción et al., 2013, Comput. Fluids).Main preliminary results show that: 1) the Alboran Ridge front fault expresses the highest tsunamigenic potentialin the area, being able to generate a tsunami with an offshore maximum wave height > 1 m for a 7.2 Mwearthquake, 2) the strike-slip fault systems have low tsunamigenic potential as expected. However, due to theinfluence of poorly-constrained parameters in the modelled tsunami scenario, a further characterization of thestrike-slip fault systems is recommended. Comparing the tsunami obtained when using the 3D fault plane withthose obtained when using the simplified planar versions, we observe systematically different wave propagationpatterns with enhanced wave heights.Collectively, our results show the importance of the fault characterization to improve the definition of thetsunamigenic potential of the tectonic structures in the Alboran Basin and provide an example for applications inother areas. Although the new data allow us to better constrain the fault geometry, there are still other importantparameters, such as the rake, that have a relatively large associated uncertainty and has an influence on the result-ing tsunami model. This is especially important for strike-slip structures, where rake variation of 10◦ produceswave-height differences of more than 0.5 m at some offshore points that may translate into non-negligible higherdifferences due to the amplification when reaching the coast.

A preliminary evaluation of the tsunamigenic potential of the active faults at the Alboran Basin (westernmost Mediterranean) based on new seismic data

http://oceanrep.geomar.de/48713/1/EGU2019-13414.pdf

A preliminary evaluation of the tsunamigenic potential of the active faults at the Alboran Basin (westernmost Mediterranean) based on new seismic data

Abstract

Similar works

Full text

Available Versions

OceanRep