Near-field propagation of tsunamis from megathrust earthquakes

We investigate controls on tsunami generation and propagation in the near-field of great megathrust earthquakes using a series of numerical simulations of subduction and tsunamigenesis on the Sumatran forearc. The Sunda megathrust here is advanced in its seismic cycle and may be ready for another great earthquake. We calculate the seafloor displacements and tsunami wave heights for about 100 complex earthquake ruptures whose synthesis was informed by reference to geodetic and stress accumulation studies. Remarkably, results show that, for any near-field location: (1) the timing of tsunami inundation is independent of slip-distribution on the earthquake or even of its magnitude, and (2) the maximum wave height is directly proportional to the vertical coseismic displacement experienced at that location. Both observations are explained by the dominance of long wavelength crustal flexure in near-field tsunamigenesis. The results show, for the first time, that a single estimate of vertical coseismic displacement might provide a reliable short-term forecast of the maximum height of tsunami waves

Guidelines for stress-test design for non-nuclear critical infrastructures and systems: Applications: STREST Reference Report 5

In the context of the STREST project, an engineering multi-level risk-based methodology to stress test critical non-nuclear infrastructures, named ST@STREST, has been developed. This reference report summarizes ST@STREST framework and its exploratory application to six key representative Critical Infrastructures (CIs) in Europe, exposed to variant hazards, namely: a petrochemical plant in Milazzo, Italy, large dams of the Valais region in Switzerland, hydrocarbon pipelines in Turkey, the Gasunie national gas storage and distribution network in Holland, the port infrastructure of Thessaloniki, Greece and an industrial district in the region of Tuscany, Italy. According to the characteristics of each case study, different stress test levels were applied. The application to the selected CIs is presented following the workflow of ST@STREST, comprised of four phases: Pre-Assessment phase; Assessment phase; Decision phase; and Report phase. First the goals, the method, the time frame, and the appropriate stress test level to apply are defined. Then, the stress test is performed at component and system levels and the outcomes are checked and compared to the acceptance criteria. A stress test grade is assigned and the global outcome is determined by employing a grading system. Finally, critical events and risk mitigation strategies are formulated and reported to stakeholders and authorities.JRC.E.4-Safety and Security of Building

A first appraisal of the seismogenic and tsunamigenic potential of the largest fault systems in the westernmost Mediterranean

15 pages, 10 figures, 3 tables, supplementary material https://doi.org/10.1016/j.margeo.2022.106749.-- Data availability: The data (3D complex mesh of the ARFS and rake values, and the resulting grid files of the tsunami simulations containing the maximum wave amplitude) are archived at PANGAEA repository (https://doi.pangaea.de/10.1594/PANGAEA.941092).-- The EMODnet bathymetry is available at https://www.emodnet-bathymetry.eu/. The stochastic slip distributions have been produced by the code ANTI-FASc (https://github.com/antonioscalaunina/ANTI-FASc) a platform partially based on the code k223d (Herrero and Murphy, 2018 available at https://github.com/s-murfy/k223d), in turn based on the slipk2 (available at https://github.com/andherit/slipk2) and the trilateration codes (available at https://github.com/andherit/trilateration)The westernmost Mediterranean hosts part of the plate boundary between the European and African tectonic plates. Based on the scattered instrumental seismicity, this boundary has been traditionally interpreted as a wide zone of diffuse deformation. However, recent seismic images and seafloor mapping studies support that most of the plate convergence may be accommodated in a few tectonic structures, rather than in a broad region. Historical earthquakes with magnitudes Mw > 6 and historical tsunamis support that the low-to-moderate instrumental seismicity might also have led to underestimation of the seismogenic and tsunamigenic potential of the area. We evaluate the largest active faults of the westernmost Mediterranean: the reverse Alboran Ridge, and the strike-slip Carboneras, Yusuf and Al-Idrissi fault systems. For the first time, we use a dense grid of modern seismic data to characterize the entire dimensions of the main fault systems, accurately describe the geometry of these structures and estimate their seismic source parameters. Tsunami scenarios have been tested based on 3D-surfaces and seismic source parameters, using both uniform and heterogeneous slip distributions. The comparison of our results with previous studies, based on limited information on the fault geometry and kinematics, indicates that accurate fault geometries and heterogeneous slip distributions are needed to properly assess the seismic and tsunamigenic potential in this area. Based on fault scaling relations, the four fault systems have a large seismogenic potential, being able to generate earthquakes with Mw > 7. The reverse Alboran Ridge Fault System has the largest tsunamigenic potential, being able to generate a tsunami wave amplitude greater than 3 m in front of the coasts of Southern Spain and Northern AfricaThis work is supported by the Cluster of Excellence “The Future Ocean”, within the framework of the Excellence Initiative by the Deutsche Forschungsgemeinschaft (DFG) on behalf of the German federal and state governments. This study benefited from an EU Marie Skłodowska-Curie Individual Fellowship to LGP (H2020-MSCA-IF-2017 796013). LGP, CS, FM and RB acknowledge the resources made available by the SISMOLAB-3D at INGV. This work has been carried out in collaboration with the Grup de Recerca Consolidat de la Generalitat de Catalunya “Barcelona Center for Subsurface Imaging” (2017 SGR 1662), and acknowledges the ICM “Severo Ochoa Centre of Excellence” accreditation (CEX2019-000928-S)Peer reviewe

Il Centro Allerta Tsunami (CAT) dell’INGV

The Tsunami Alert Centre of the INGV (CAT-INGV) was created with the aim of contributing to the mitigation of the risk due to tsunamis triggered by earthquakes on the Italian and Mediterranean coasts. Tsunamis of seismic origin, in addition to being the most frequent, are those that can be detected more quickly. Seismic waves, in fact, travel in the crust with a much higher speed than that of tsunami waves. With effective seismic networks connected in real time, an "Early Warning" system can be implemented, i.e. a system capable of sending an alert signal before the arrival of the tsunami waves, at least from a certain distance from the source. The CAT-INGV has two main tasks. The first one is to provide alerts to the competent authorities in the event of potential tsunamigenic earthquakes in the Mediterranean, taking into account the criteria defined by the Department of Civil Protection for this purpose. The second one consists in carrying out the necessary studies for the definition of the probabilistic danger of tsunamis for the Italian coasts, starting from those of seismic origin (Seismic Probabili-stic Tsunami Hazard Analysis, SPTHA). In this contribution the first aspect is described, while the realization of the studies on hazard at the Mediterranean scale is the subject of research described in various recent articles (Lorito et al., 2015; Grezio et al., 2017; Selva et al., 2017a; Selva et al., 2017b). The TSUMAPS-NEAM project, funded by the European Commission and concluded at the end of 2017, provided the first hazard map for the Mediterranean region and the north-east Atlantic (Basili et al., 2017).Published91-975T. Modelli di pericolosità sismica e da maremotoN/A or not JC

The Italian Earthquakes and Tsunami Monitoring and Surveillance Systems

The Osservatorio Nazionale Terremoti (ONT) is the Italian seismic operational centre for monitoring earthquake, it is part of Istituto Nazionale di Geofisica e Vulcanologia (INGV) the largest Italian research institution, with focus in Earth Sciences. INGV runs the Italian National Seismic Network (network code IV) and other networks at national scale for monitoring earthquakes and tsunami. INGV is a primary node of European Integrated Data Archive (EIDA) for archiving and distributing, continuous, quality checked seismic waveforms (strong motion and weak motion recordings). ONT designed the data acquisition system to accomplish, in near-real-time, automatic earthquake detection, hypocentre and magnitude determination and evaluation of moment tensors, shake maps and other products. Database archiving of all parametric results are closely linked to the existing procedures of the INGV seismic monitoring environment and surveillance procedures. ONT organize the Italian earthquake surveillance service and the tsunami alert service (INGV is Tsunami Service Provider of the ICG/NEAM for the entire Mediterranean basin). We provide information to the Dipartimento di Protezione Civile (DPC) and to several Mediterranean countries. Earthquakes information are revised routinely by the analysts of the Italian Seismic Bulletin. The results are published on the web and are available to the scientific community and the general public.PublishedMontreal1SR TERREMOTI - Sorveglianza Sismica e Allerta Tsunam

Finite-element numerical simulation of tsunamis generated by earthquakes near a circular island

Abstract A numerical model for the propagation of tsunamis generated by earthquakes is applied to study the impact of the water waves against the coast of a circular island. The hydraulic source is modeled by means of the static deformation of the seafloor produced by an offshore seismic fault. The initial sea-surface disturbance is assumed to equal the seabed displacement that is computed analytically through the classical dislocation theory of plane faults with uniform slip. The wave propagation is described by means of the shallow-water approximation of the Navier-Stokes equations and is computed in a radially symmetric domain for which a quasi-analytical solution is available. The governing equations are solved numerically by means of a finite-element (FE) method making use of the Galerkin procedure, the mesh consisting of triangular elements of variable size. After a preliminary test of the numerical model against the analytical results, several simulations are performed by varying the fault location, dimension, and dip as well as by varying the radial profiles of the basin bathymetry. Most attention is devoted to studying the amplification of tsunami waves impacting the island coast. What is seen is that, depending on the source characteristics (namely, fault length, dip, strike, and distance from the island) and on the basin bathymetry, high amplifications (in the range 1 to 5) are normally obtained not only in the front of the island as is expected but also on the lee side of the island, because of positive interference of waves traveling around the island in both directions. Under particular conditions (downwardly concave bathymetry), the largest amplifications are found neither on the front side nor on the lee side, but at intermediate places along the island coast.</jats:p