Modeling of SMF tsunami hazard along the upper US East Coast: detailed impact around Ocean City, MD

Abstract

With support from the US National Tsunami Hazard Mitigation Program (NTHMP), the authors have been developing tsunami inundation maps for the upper US East Coast (USEC), using high-resolution numerical modeling. These maps are envelopes of maximum elevations, velocity, or momentum flux, caused by the probable maximum tsunamis identified in the Atlantic oceanic basin, including from far-field coseismic or volcanic sources, and near-field Submarine mass failures (SMFs); the latter are the object of this work. Despite clear field evidence of past large-scale SMFs within our area of interest, such as the Currituck slide complex, their magnitude, pre-failed geometry, volume, and mode of rupture are poorly known. A screening analysis based on the Monte Carlo simulations (MCS) identified areas for possible tsunamigenic SMF sources along the USEC, indicating an increased level of tsunami hazard north of Virginia, potentially surpassing the inundation generated by a typical 100-year hurricane storm surge in the region, as well as that from the most extreme far-field coseismic sources in the Atlantic; to the south, the MCS indicated that SMF tsunami hazard significantly decreased. Subsequent geotechnical and geological analyses delimited four high-risk areas along the upper USEC where the potential for large tsunamigenic SMFs, identified in the MCS, was realistic on the basis of field data (i.e., sediment nature and volume/availability). In the absence of accurate site-specific field data, following NTHMP's recommendation, for the purpose of simulating tsunami hazard from SMF PMTs, we parameterized an extreme SMF source in each of the four areas as a so-called Currituck proxy, i.e., a SMF having the same volume, dimensions, and geometry as the historical SMF. In this paper, after briefly describing our state-of-the-art SMF tsunami modeling methodology, in a second part, we parameterize and model the historical Currituck event, including: (1) a new reconstruction of the SMF geometry and kinematics; (2) the simulation of the resulting tsunami source generation; and (3) the propagation of the tsunami source over the shelf to the coastline, in a series of nested grids. A sensitivity analysis to model and grid parameters is performed on this case, to ensure convergence and accuracy of tsunami simulation results. Then, we model in greater detail and discuss the impact of the historical Currituck tsunami event along the nearest coastline where its energy was focused, off of Virginia Beach and Norfolk, as well as near the mouth of the Chesapeake Bay; our results are in qualitative agreement with an earlier modeling study. In a third part, following the same methodology, we model tsunami generation and propagation for SMF Currituck proxy sources sited in the four identified areas of the USEC. Finally, as an illustration of our SMF tsunami hazard assessment work, we present detailed tsunami inundation maps, as well as some other products, for one of the most impacted and vulnerable areas, near and around Ocean City, MD. We find that...

Far-Field Tsunami Impact in the North Atlantic Basin from Large Scale Flank Collapses of the Cumbre Vieja Volcano, La Palma

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Effects of a Macro-Roughness Element on Tsunami Wave Amplification, Pressures, and Loads: Physical Model and Comparison to Japanese and US Design Equations

“…However, individual damage depends on local building structure and design, even under the same hydrodynamic conditions. Moreover, wavestructure interaction is difficult to model [Petukhin et al, 2012], and many models remove buildings to allow for more efficient calculations [see Westerink et al, 2008;Parsons et al, 2014;Yao et al, 2014;Grilli et al, 2015]. Such simplifications can result in errors in hydrodynamic outputs.…”

Riesgo de tsunami y planificación resiliente de la costa chilena: La localidad de Boca Sur, San Pedro de la Paz (37° S)

“…Asumiendo una tradición importante que defi ne el riesgo natural como la plasmación territorial de una actuación humana poco acorde con las características físico-naturales del territorio donde tiene lugar (Blaikie et al, 1994;Rojas y Martínez, 2011), los factores principales están dados por la valoración de las condiciones asociadas a la amenaza (tsunami) y a la vulnerabilidad, que defi nen el riesgo. En el caso de la amenaza, la atención ha estado en determinar a través de modelamiento numérico, el comportamiento hidrodinámico del tsunami y su impacto en la infraestructura, especialmente a través de curvas de fragilidad (Suppasri et al, 2011;Mas et al, 2012;Sugawara & Goto, 2012;Grilli et al, 2015;Prerna et al, 2015). Por su parte, la vulnerabilidad ha sido uno de los aspectos más discutidos por su difícil valoración en los procesos sociales y territoriales cambiantes.…”