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- The contribution of submarine optical fiber telecom cables to the monitoring of earthquakes and tsunamis in the NE AtlanticPublication . Matias, Luis; Carrilho, Fernando; Sá, Vasco; Omira, Rachid; Niehus, Manfred; Corela, Carlos; Barros, José; Omar, YasserRecent developments in optical fiber cable technology allows the use of existing and future submarine telecommunication cables to provide seismic and sea-level information. In this work we study the impact of three different technologies, 1) SMART, Science Monitoring and Reliable Telecommunications; 2) DAS, Distributed Acoustic Sensing, and; 3) LI, Laser Interferometry, for effective earthquake and tsunami monitoring capabilities on the NE Atlantic. The SW Iberia is the source area of the largest destructive earthquake that struck Europe since the year 1000, the November 1, 1755 event. This earthquake generated also a destructive tsunami affecting the whole basin. This tectonically active area is crossed by the CAM (Continent-Azores-Madeira) submarine cable on a ring configuration. Due to the end of cable lifetime the current cables need to be replaced by 2024 and the technical requirements must be defined in mid-2021. The Azores archipelago is the focus of frequent seismic crizes and occasionally destructive earthquakes. A common feature of these seismic events is that they take place offshore, an area that is difficult to monitor from land-based instruments. In this work we evaluate the contribution of SMART cables to the earthquake monitoring and tsunami early warning system in SW Iberia and show how DAS and LI can improve earthquake monitoring on two active domains of the Azores. For tsunami early warning, we show how the offshore sea-level measurements provide clean offshore tsunami records when compared to coastal observations by tide gauges, which greatly improves the efficiency of the system. For earthquake monitoring, the data processing operational routine is examined using Monte-Carlo simulations. These take into consideration the errors in phase picking and the uncertainty on the 1D velocity model used for earthquake location. Quality of earthquake location is examined using the difference between the true location and the centroid of the computed epicenters and by the overall ellipse of uncertainty obtained from 100 runs. The added value provided by instrumented submarine telecommunication cables to mitigate earthquake and tsunami risk demonstrated in this work will help authorities and the society in general to take the political decisions required for its full implementation worldwide.
- The making of the NEAM Tsunami Hazard Model 2018 (NEAMTHM18)Publication . Basili, Roberto; Brizuela, Beatriz; Herrero, Andre; Iqbal, Sarfraz; Lorito, Stefano; Maesano, Francesco Emanuele; Murphy, Shane; Perfetti, Paolo; Romano, Fabrizio; Scala, Antonio; SELVA, Jacopo; Taroni, Matteo; Tiberti, Mara Monica; Thio, Hong Kie; Tonini, Roberto; Volpe, Manuela; Glimsdal, Sylfest; Harbitz, Carl Bonnevie; Lovholt, Finn; Baptista, Maria Ana Carvalho Viana; Carrilho, Fernando; Matias, Luis; Omira, Rachid; Babeyko, Andrey; Hoechner, Andreas; Gurbuz, Mucahit; Pekcan, Onur; Yalciner, Ahmet; Canals, Miquel; Lastras, Galderic; Agalos, Apostolos; Papadopoulos, Gerassimos; TRIANTAFYLLOU, IOANNA; Benchekroun, Sabah; Jaouadi, Hedi Agrebi; Ben Ahmed, Samir; Bouallegue, Atef; Hamdi, Hassene; Oueslati, Foued; Amato, Alessandro; ARMIGLIATO, ALBERTO; Behrens, Joern; Davies, Gareth; Di Bucci, Daniela; Dolce, Mauro; Geist, Eric; GONZALEZ-VIDA, J.M.; Gonzalez, Mauricio; Macías, Jorge; Meletti, Carlo; Sozdinler, Ceren Ozer; Pagani, Marco; Parsons, Tom; Polet, Jascha; Power, William; Sorensen, Mathilde; Zaytsev, AndreyThe 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 threephase 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 (P01) 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 approximate to 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. NEAMTHM1 8 results and documentation are available through the TSUMAPS-NEAM project website (http://www.tsumaps-neam.eu/), featuring an interactive web mapper. Although the NEAMTHM1 8 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.
- Intraplate seismicity across the Cape Verde swell: a contribution from a temporary seismic networkPublication . Vales, Dina; Dias, Nuno; Rio, Inês; Matias, Luís; Silveira, Graça; Madeira, JFA; Webber, Michael; Carrilho, Fernando; Haberland, ChristianWe present an analysis and characterization of the regional seismicity recorded by a temporary broadband seismic network deployed in the Cape Verde archipelago between November 2007 and September 2008. The detection of earthquakes was based on spectrograms, allowing the discrimination from low-frequency volcanic signals, resulting in 358 events of which 265 were located, the magnitudes usually being smaller than 3. For the location, a new 1-D P-velocity model was derived for the region showing a crust consistent with an oceanic crustal structure. The seismicity is located mostly offshore the westernmost and geologically youngest areas of the archipelago, near the islands of Santo Antao and Sao Vicente in the NW and Brava and Fogo in the SW. The SW cluster has a lower occurrence rate and corresponds to seismicity concentrated mainly along an alignment between Brava and the Cadamosto seamount presenting normal faulting mechanisms. The existence of the NW cluster, located offshore SW of Santo Antao, was so far unknown and concentrates around a recently recognized submarine cone field; this cluster presents focal depths extending from the crust to the upper mantle and suggests volcanic unrest No evident temporal behaviour could be perceived, although the events tend to occur in bursts of activity lasting a few days. In this recording period, no significant activity was detected at Fogo volcano, the most active volcanic edifice in Cape Verde. The seismicity characteristics point mainly to a volcanic origin. The correlation of the recorded seismicity with active volcanic structures agrees with the tendency for a westward migration of volcanic activity in the archipelago as indicated by the geologic record. (C) 2014 Elsevier B.V. All rights reserved.