Monday, September 17, 2012 12:22
A devastating earthquake/volcanic eruption leading to a landslide in the Canary Islands may only leave US East Coast residents a 6 hour warning. With the recent earthquakes in the region picking up dramatically, the internet is going abuzz about the possibilities of a tsunami strike along the US East Coast. Youtube reporter Mary Greeley examines these possibilities and the startling uptick in seismic activity in the Canary Islands in the video below. What would a large scale flank collapse and landslide mean to Americans? The video at the bottom of the story outlines the alarming possibilities of such a catastrophic scenario.
Large landslides are inherent to the volcanic building process as material continuously accumulates until the point of slope failure (Holcomband Searle, 1991). Debris avalanche deposits were for instance found in Hawaii (Moore et al., 1989; Robinson and Eakins, 2006) or at R´eunion Island (Cochonat et al., 1990; Oehler et al., 2004). There is also clear geological evidence of past large paleo-submarine landslides of O(100 km3)volume around the Canary Islands (Spain). Masson et al. (2002) identiﬁed at least 14 large landslides, which have occurred on the ﬂanks of the youngest Canary Islands (i.e., El Hierro, La Palma, and Tenerife) in the last one million years, with the youngest one, at El Hierro, being only 15,000 years old. Even much smaller debris ﬂows can be quite destructive: the tsunami triggered by the 0.5 km3 Shimabara ﬂank collapse in 1792 killed at least 4,000 people (Inoue, 2000).
Canary Islands, have the potential for generating vastly more destructive waves (i.e., mega-tsunami; Ward and Day, 2001). Such potentially catastrophic events may occur in average every 100,000 years in the Canary Archipelago. However, low probability does not necessarily mean low risk; so for proper tsunami hazard assessment, the consequences associated with such catastrophic events must be carefully estimated and modeled.