NEAMTHM18

European-Union Civil Protection Mechanism, DG-ECHO, Agreement Number: ECHO/SUB/2015/718568/PREV26Published6T. Studi di pericolosità sismica e da maremoto1SR TERREMOTI - Sorveglianza Sismica e Allerta Tsunami2SR TERREMOTI - Gestione delle emergenze sismiche e da maremoto4IT. Banche dat

The making of the NEAM Tsunami Hazard Model 2018 (NEAMTHM18)

The NEAM Tsunami Hazard Model 2018 (NEAMTHM18) is a probabilistic hazard model for tsunamis generated by earthquakes. It covers the coastlines of the North-eastern Atlantic, the Mediterranean, and connected seas (NEAM). NEAMTHM18 was designed as a three-phase project. The first two phases were dedicated to the model development and hazard calculations, following a formalized decision-making process based on a multiple-expert protocol. The third phase was dedicated to documentation and dissemination. The hazard assessment workflow was structured in Steps and Levels. There are four Steps: Step-1) probabilistic earthquake model; Step-2) tsunami generation and modeling in deep water; Step-3) shoaling and inundation; Step-4) hazard aggregation and uncertainty quantification. Each Step includes a different number of Levels. Level-0 always describes the input data; the other Levels describe the intermediate results needed to proceed from one Step to another. Alternative datasets and models were considered in the implementation. The epistemic hazard uncertainty was quantified through an ensemble modeling technique accounting for alternative models' weights and yielding a distribution of hazard curves represented by the mean and various percentiles. Hazard curves were calculated at 2,343 Points of Interest (POI) distributed at an average spacing of ∼20 km. Precalculated probability maps for five maximum inundation heights (MIH) and hazard intensity maps for five average return periods (ARP) were produced from hazard curves. In the entire NEAM Region, MIHs of several meters are rare but not impossible. Considering a 2% probability of exceedance in 50 years (ARP≈2,475 years), the POIs with MIH >5 m are fewer than 1% and are all in the Mediterranean on Libya, Egypt, Cyprus, and Greece coasts. In the North-East Atlantic, POIs with MIH >3 m are on the coasts of Mauritania and Gulf of Cadiz. Overall, 30% of the POIs have MIH >1 m. NEAMTHM18 results and documentation are available through the TSUMAPS-NEAM project website (http://www.tsumaps-neam.eu/), featuring an interactive web mapper. Although the NEAMTHM18 cannot substitute in-depth analyses at local scales, it represents the first action to start local and more detailed hazard and risk assessments and contributes to designing evacuation maps for tsunami early warning

The Making of the NEAM Tsunami Hazard Model 2018 (NEAMTHM18)

ABSTRACT: The NEAM Tsunami Hazard Model 2018 (NEAMTHM18) is a probabilistic hazard model for tsunamis generated by earthquakes. It covers the coastlines of the North-eastern Atlantic, the Mediterranean, and connected seas (NEAM). NEAMTHM18 was designed as a three-phase project. The first two phases were dedicated to the model development and hazard calculations, following a formalized decision-making process based on a multiple-expert protocol. The third phase was dedicated to documentation and dissemination. The hazard assessment workflow was structured in Steps and Levels. There are four Steps: Step-1) probabilistic earthquake model; Step-2) tsunami generation and modeling in deep water; Step-3) shoaling and inundation; Step-4) hazard aggregation and uncertainty quantification. Each Step includes a different number of Levels. Level-0 always describes the input data; the other Levels describe the intermediate results needed to proceed from one Step to another. Alternative datasets and models were considered in the implementation. The epistemic hazard uncertainty was quantified through an ensemble modeling technique accounting for alternative models' weights and yielding a distribution of hazard curves represented by the mean and various percentiles. Hazard curves were calculated at 2,343 Points of Interest (POI) distributed at an average spacing of ∼20 km. Precalculated probability maps for five maximum inundation heights (MIH) and hazard intensity maps for five average return periods (ARP) were produced from hazard curves. In the entire NEAM Region, MIHs of several meters are rare but not impossible. Considering a 2% probability of exceedance in 50 years (ARP≈2,475 years), the POIs with MIH >5 m are fewer than 1% and are all in the Mediterranean on Libya, Egypt, Cyprus, and Greece coasts. In the North-East Atlantic, POIs with MIH >3 m are on the coasts of Mauritania and Gulf of Cadiz. Overall, 30% of the POIs have MIH >1 m. NEAMTHM18 results and documentation are available through the TSUMAPS-NEAM project website (http://www.tsumaps-neam.eu/), featuring an interactive web mapper. Although the NEAMTHM18 cannot substitute in-depth analyses at local scales, it represents the first action to start local and more detailed hazard and risk assessments and contributes to designing evacuation maps for tsunami early warning

Προσδιορισμός σεισμικών παραμέτρων με την μέθοδο αντιστροφής του τανυστή της σεισμικής ροπής

A moment tensor inversion technique was applied using data at teleseismic and regional distances. The inversion technique was applied for earthquakes occurred in Greece and surrounding countries. Another inversion technique used in order to calculate slip models for the strongest events of Greece from 1995. The same technique used to calculate slip models for strong earthquakes around the world. The obtained slip models were used to calculate seismic ground velocity maps. Co seismic static stress changes were also calculated based on the slip models.Η παρούσα διδακτορική διατριβή πραγματεύεται τον υπολογισμό των σεισμικών παραμέτρων με τη διαδικασία υπολογισμού συνθετικών κυμάτων και την αντιστροφή του τανυστή της σεισμικής ροπής. Επίσης η χωρική εξάπλωση της συνσεισμικής ολίσθησης πάνω στο ρήγμα που προήλθε από την αντιστροφή κρίθηκε αναγκαία για το λεπτομερή προσδιορισμό στατικών τάσεων Coulomb καθώς και για τη χαρτογράφηση της ισχυρής σεισμικής κίνησης. Αρχικά, αναπτύσσεται αναλυτικά η θεωρία που σχετίζεται με την αντιστροφή του τανυστή της σεισμικής ροπής. Στη συνέχεια, υπάρχουν εφαρμογές για σεισμούς της Ελλάδος. Μοντέλα ολίσθησης υπολογίστηκαν για τους ισχυρότερους σεισμούς της Ελλάδος από το 1995. Η διατριβή παρέχει γνώση για τους ισχυρούς σεισμούς της Ελλάδος

Seismic and Geodetic Imaging (DInSAR) Investigation of the March 2021 Strong Earthquake Sequence in Thessaly, Central Greece

Three strong earthquakes ruptured the northwest Thessaly area, Central Greece, on the 3, 4 and 12 March 2021. Since the area did not rupture by strong earthquakes in the instrumental period of seismicity, it is of great interest to understand the seismotectonics and source properties of these earthquakes. We combined relocated hypocenters, inversions of teleseismic P-waveforms and of InSAR data, and moment tensor solutions to produce three fault models. The first shock (M-w = 6.3) occurred in a fault segment of strike 314 degrees and dip NE41 degrees. It caused surface subsidence -40 cm and seismic slip 1.2-y1.5 m at depth similar to 10 km. The second earthquake (M-w = 6.2) occurred to the NW on an antithetic subparallel fault segment (strike 123 degrees, dip SW44 degrees). Seismic slip of 1.2 m occurred at depth of similar to 7 km, while surface subsidence -10 cm was determined. Possibly the same fault was ruptured further to the NW on 12 March (M-w = 5.7, strike 112 degrees, dip SSW42 degrees) that caused ground subsidence -5 cm and seismic slip of 1.0 m at depth similar to 10 km. We concluded that three blind, unknown and unmapped so far normal fault segments were activated, the entire system of which forms a graben-like structure in the area of northwest Thessaly

Fault models for the Bodrum–Kos tsunamigenic earthquake (Mw6.6) of 20 July 2017 in the east Aegean Sea

We investigate a fault model for the shallow, strong (Mw6.6) tsunamigenic earthquake of 20 July 2017 with source area in the east Aegean Sea between Bodrum peninsula (Turkey) and Kos Isl. (Greece). Fault plane solutions are consistent with the regional active tectonics indicating normal faulting striking about E–W. A relocated hypocenter of the main shock was obtained and the rupture time-space history for two alternative fault solutions dipping either to the south or to north was approached by inverting P-waves recorded at teleseismic (30°–90°) distances. In both fault solutions the seismic moment calculated corresponds to magnitude Mw=6.6 while the earthquake had total rupture duration of less than 10 s. The maximum co-seismic slip was close to the hypocenter ∼1.6m and ∼2.2m for the south and north dipping faults, respectively. Close to the surface coseismic slip of ∼0.3m was calculated. Our analysis of Sentinel satellite InSAR images showed ground deformation fringes indicating ∼13 cm vertical displacement change between the North and South coasts of the Karaada islet. This result is in line with our preference of the south dipping fault, supported primarily by GPS displacements, regional tectonics, aftershock activity and tsunami observations, although results of InSAR inversion fit equally well both solutions.Published1016463T. Sorgente sismicaJCR Journa