Reconstructions from sedimentary records show that canyons undergo flushing infrequently (102- to 103-year time scales), and on passive margin canyons, this might occur only during periods of glacially lowered sea level and direct sediment supply (7, 12).

Although many studies have tried to provide solutions for measuring vulnerability, and there is a wide range of vulnerability quantifying methods (for example, Turner et al. 2003; van der Veen et al. 2009; Sterlacchini et al. 2014), a fundamental challenge remains how to make vulnerability operational (Hinkel 2011).

In a 2005 study, Ruth Ludwin, then a seismologist at the University of Washington, together with nine colleagues, collected and analyzed Native American reports of earthquakes and saltwater floods.