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Coastal water level variations
Published in Dominic Reeve, Andrew Chadwick, Christopher Fleming, Coastal Engineering, 2018
Dominic Reeve, Andrew Chadwick, Christopher Fleming
More recently still, another earthquake (the Tōhoku earthquake) occurred off the eastern coast of Japan, triggering a huge tsunami. The earthquake was a 9.0 Mw undersea megathrust earthquake that occurred at 14:46 JST (05:46 UTC) on Friday, 11 March 2011. The earthquake triggered huge tsunami waves (over 30 m height in some places according to local press), that struck Japan minutes after the quake, in some cases travelling up to 10 km inland. There was a huge loss of life and massive destruction of houses and infrastructure. Also, the nuclear power plant at Fukushima was damaged leading to the escape of radioactive compounds. ‘Extensive damage occurred, including melting of the cores and high radioactive releases,’ with a sequence of strong (∼6.0 Mw) aftershocks hampering the rescue and restoration efforts. The event is notable because Japan is well known for being well protected against tsunamis. In this case the magnitude of the event exceeded the criteria used in the design of the defences, which may well be revised in light of the consequences of the flooding caused by the tsunami.
Influence of ground motion duration on the seismic vulnerability of aging highway bridges
Published in Structure and Infrastructure Engineering, 2023
Bhaskar Panchireddi, Shivang Shekhar, Jayadipta Ghosh
Several past studies on ground motion modelling (Bard & Bouchon, 1980; Olsen, Stephenson, & Geisselmeyer, 2008) reveals that earthquakes within the geographical region of Seattle could be damaging for local civil engineering structures. Located within the Cascadia subduction zone along the Pacific Northwest Coast of the United States, Seattle is susceptible to experience long duration and large magnitude earthquakes in addition to less-damaging seismic shaking. For instance, the Seattle fault zone comprises of a network of crustal or shallow earthquakes that occur in the North American plate at 0–30 km from the crust’s surface along the fault and typically results in less-intense seismic shaking with moment magnitude Mw < 7.0; even though crustal earthquakes with Mw = 7.5 has also been documented. On the other hand, the interface between the North American plate and the San Juan de Fuca plate extending from Northern California to British Columbia is known to generate subduction or megathrust earthquakes. Compared to the crustal counterpart, these subduction earthquakes are substantially more intense with moment magnitudes that can exceed 9.0. As the largest city in both the state of Washington and the Pacific Northwest region of North America, such earthquake occurrences in Seattle are expected to have consequences that are prolonged and catastrophic.
Tsunami hazard assessment for the central and southern pacific coast of Colombia
Published in Coastal Engineering Journal, 2020
Ronald Sanchez Escobar, Luis Otero Diaz, Anlly Melissa Guerrero, Milton Puentes Galindo, Erick Mas, Shunichi Koshimura, Bruno Adriano, Luisa Urra, Paola Quintero
Megathrust earthquakes are extremely large inverse-fault earthquakes. These events occur at plate interfaces along subduction zones and generally reach magnitudes of approximately Mw 8.5; they are especially destructive when they exceed Mw 9.0 (Mas et al. 2015). In 1906, a large earthquake (considered a megaquake with a magnitude of approximately Mw 8.5) broke the entire interface between the Nazca Plate and the South American Plate. Similarly, in 1979, another strong earthquake (Mw 8.3) occurred in the Colombo-Ecuadorian subduction zone and significantly affected the population of San Juan de la Costa, located in the northern part of Tumaco, Nariño (Dimar-CCCP 2013).