JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.The University of Chicago Press is collaborating with JSTOR to digitize, preserve and extend access to The Journal of Geology. A B S T R A C TThis article presents a reasonable present-day, sea-level highstand numerical simulation and scenario for a potential tsunami generated by a landslide with the characteristics of the BIG'95 debris flow, which occurred on the Ebro margin in the western Mediterranean Sea in prehistoric times (11,500 cal yr BP). The submarine landslide deposit covers an area of 2200 km 2 of the slope and base of slope (200-1800-m water depth), involving a volume of 26 km 3 . A leapfrog finite difference model, COMCOT (Cornell multigrid coupled tsunami model), is used to simulate the propagation of the debris-flow-generated tsunami and its associated impact on the nearby Balearic Islands and Iberian coastlines. As a requisite of the model, reconstruction of the bathymetry before the landslide occurrence and seafloor variation during landsliding have been developed based on the conceptual and numerical model of Lastras et al. (2005). We have also taken into account all available multibeam bathymetry of the area and high-resolution seismic profiles of the debris flow deposit. The results of the numerical simulation are displayed using plots of snapshots at consecutive times, marigrams of synthetic stations, maximum amplitude plots, and spectral analyses. The obtained outputs show that the nearest shoreline, the Iberian coast, would not be the first one hit by the tsunami. The eastward, outgoing wave would arrive at Eivissa Island 18 min after the triggering of the slide and at Mallorca Island 9 min later, whereas the westward-spreading wave would hit the Iberian Peninsula 54 min after the slide was triggered. This noticeable delay in the arrival times at the peninsula is produced by the asymmetric bathymetry of the Catalano-Balearic Sea and the shoaling effect due to the presence of the wide Ebro continental shelf, which in addition significantly amplifies the tsunami wave (19 m). The wave amplitudes attain 8 m in Eivissa, and waves up to 3 m high would arrive to Palma Bay. Resonance effects produced in the narrow Santa Ponç a Bay in Mallorca Island could produce waves up to 9 m high. A similar event occurring today would have catastrophic consequences, especially in summer when human use of these tourist coasts increases significantly.
HighlightsCanyon incision, width and orientation modify tsunami wave arrival and run-up.Shoreward of a canyon head, tsunami height diminishes with increased incision.At both sides of the canyon, tsunami wave height increases.The presence of a canyon incised very close to the coast can produce edge waves. We analyse the variations produced on tsunami propagation and impact over a straight coastline 20 because of the presence of a submarine canyon incised in the continental margin. For ease of 21 calculation we assume that the shoreline and the shelf edge are parallel and that the incident wave 22 approaches them normally. A total of 512 synthetic scenarios have been computed by combining the 23 bathymetry of a continental margin incised by a parameterised single canyon and the incident 24 tsunami waves. The margin bathymetry, the canyon and the tsunami waves have been generated 25 using mathematical functions (e.g. Gaussian). Canyon parameters analysed are: (i) incision length into 26 the continental shelf, which for a constant shelf width relates directly to distance from the canyon 27 head to the coast, (ii) canyon width, and (iii) canyon orientation with respect to the shoreline. 28Tsunami wave parameters considered are period and sign. The COMCOT tsunami model from Cornell 29University was applied to propagate the waves across the synthetic bathymetric surfaces. Five 30 simulations of tsunami propagation over a non-canyoned margin were also performed for reference. 31 32The analysis of the results reveals a strong variation of tsunami arrival times and amplitudes reaching 33 the coastline when a tsunami wave travels over a submarine canyon, with changing maximum height 34 location and alongshore extension. In general, the presence of a submarine canyon lowers the arrival 35 time to the shoreline but prevents wave build-up just over the canyon axis. This leads to a decrease in 36 tsunami amplitude at the coastal stretch located just shoreward of the canyon head, which results in 37 a lower run-up in comparison with a non-canyoned margin. Contrarily, an increased wave build-up 38 occurs on both sides of the canyon head, generating two coastal stretches with an enhanced run-up. 39These aggravated or reduced tsunami effects are modified with (i) proximity of the canyon tip to the 40 coast, amplifying the wave height, (ii) canyon width, enlarging the areas with lower and higher 41 maximum height wave along the coastline, and (iii) canyon obliquity with respect to the shoreline and 42 shelf edge, increasing wave height shoreward of the leeward flank of the canyon. Moreover, the 43 presence of a submarine canyon near the coast produces a variation of wave energy along the shore, Tsunami; multi-scenario; numerical simulation; submarine canyon 54 55
On 21 April 2007, an Mw 6.2 earthquake produced an unforeseen chain of events in the Aysén fjord (Chilean Patagonia, 45.5°S). The earthquake triggered hundreds of subaerial landslides along the fjord flanks. Some of the landslides eventually involved a subaqueous component that, in turn, generated a series of displacement waves—tsunami‐like waves produced by the fast entry of a subaerial landmass into a water body—within the fjord [Naranjo et al., 2009; Sepúlveda and Serey, 2009; Hermanns et al., 2013]. These waves, with run‐ups several meters high along the shoreline, caused 10 fatalities. In addition, they severely damaged salmon farms, which constitute the main economic activity in the region, setting free millions of cultivated salmon with still unknown ecological consequences.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.