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Gujarat Earthquake
Published in Ramesh P. Singh, Darius Bartlett, Natural Hazards, 2018
The Rann of Kachchh is an ideal ground for earthquake-induced liquefaction features due to its thick pile of clay, sand and silt-dominated soft sediments. Hence, this geomorphic unit preserves seismite-like features, such as convolutions of finer sediments, folds, flame structures and sand dykes. Excavations at large sand blow craters near Umedpar are made for their source parameters, and characterization reveals seismite-type deformations in clayey sediments of the Banni plains (Figure 1.12).
Paleoseismic event recorded in the Upper Cretaceous Nenjiang Formation in southeastern area of the Songliao Basin (NE China)
Published in Australian Journal of Earth Sciences, 2019
Modern earthquakes can be detected and reported by advanced observation equipment, but paleo-earthquakes cannot be detected by artificial instruments. Paleoseismicity is commonly based on the interpretation of high-resolution seismic reflection profiles and using cores and well logs (Arnaud et al., 2002; Carrillo, Beck, Audemard, Moreno, & Ollarves, 2008; Tian et al., 2017; Wagner et al., 2008). Common paleoseismic indicators, which refer to both hard-rock and soft-sediment beds containing different deformation structures produced by earthquake induced shock waves and interpreted as “seismites” (Seilacher, 1969, 1991), have been described from the deposits ranging in age from middle–upper Proterozoic to the recent and from all sedimentary environments, including lacustrine and fluvial deposits. Generally, synsedimentary or penecontemporaneous deformation structures are commonly referred to as soft-sediment deformation structures (abbreviated as “SSDSs”; Ezquerro, Moretti, Liesa, Luzón, & Simón, 2015; Moretti, 2000; Moretti & Sabato, 2007; Pratt, 1943; Törő & Pratt, 2016). Different types of seismites, which have been studied through simulation experiments, can be used to assess the trigger mechanism of SSDSs (Moretti, Alfaro, Caselles, & Canas, 1999; Nichols, Sparks, & Wilson, 1994). The occurrence of seismites, which commonly indicates frequent tectonic activities in a region, is of great significance in paleotectonic analysis and providing evidence for paleo-environment restorations, ancient faults and stratigraphic correlations. Moreover, the formation age and spatial distribution of seismites can be used to reflect and understand the intensity, magnitude and spheres of paleo-earthquakes (Mörner, 1989; Obermeier et al., 1990; Owen, 1996).