Lagoon subsidence and tsunami on the West Coast of New Zealand

Review Article: Potential geomorphic consequences of a future great (<i>M</i><sub>w</sub> = 8.0+) Alpine Fault earthquake, South Island, New Zealand

“…Evidence from the Okarito lagoon in West Coast region suggests that this was once briefly flooded. Nichol et al (2007) used trenching and coring techniques within the lagoon and identified features they described as typical of a tsunami event. C 14 dating of an in situ buried bivalve dates this event to the mid-15th century, roughly when the ca.…”

“…C 14 dating of an in situ buried bivalve dates this event to the mid-15th century, roughly when the ca. AD 1460 Alpine Fault event occurred (Nichol et al, 2007). Because the Alpine Fault is mainly onshore and dominantly strike slip in character, coastal tsunami are most likely to be generated by coseismic sediment slumps in offshore canyon heads.…”

“…Because the Alpine Fault is mainly onshore and dominantly strike slip in character, coastal tsunami are most likely to be generated by coseismic sediment slumps in offshore canyon heads. However, what Nichol et al (2007) identified as a tsunami deposit may alternatively be a liquefaction deposit. Lagoons like Okarito are highly susceptible to liquefaction under intense shaking and it is almost certain the Okarito lagoon will have experienced high intensity shaking during all Alpine Fault events.…”

The role of neo-tectonics in the sedimentary infilling and geomorphological evolution of the Guadalquivir estuary (Gulf of Cadiz, SW Spain) during the Holocene

“…3 neotectonics) ought to be included as a factor as well; in combination with the other parameters, it may cause changes in the sedimentation rates, result in the creation of new geomorphological features (spits, dunes, cheniers, marshes, levees, alluvial soils), sea-level oscillations (Kennedy, 2011;Yeager et al, 2012;Feagín et al, 2013) and associated tsunami and storm inundation (Morton et al, 2007;Nichol et al, 2007). The subsidence lowers tidal salt-marshes and fertile lowlands below the level of the sea, which thereafter deposits layers of sediments on the former sub-aerial surfaces until fresh alluvial sedimentation overrides these layers, only to be buried below sea level in the next subsidence cycle (Bolt, 2003).…”

Geochemistry of surface sediments in tsunami-affected Sri Lankan lagoons regarding environmental implications

“…Higher abundances of As, Cl, Br, S and organic matter in sedimentary sequences in some coastal wetland environments such as lagoons and marshy lands reflect the influences of tsunami and sea level changes on the coast (López-Buendía et al 1999;Chagué-Goff et al 2000. The presences of higher values of Fe, Sr, Ca and S have also been linked to lagoon subsidence associated with tsunami inundation (Nichol et al 2007).…”