Guest editorial: Paleotsunami

Abstract

An 8.9 M earthquake hit northeast Japan on March 11, 2011 which was followed by several aftershocks and series of disastrous tsunamis causing devastation in the region. The most disastrous tsunami event in terms of loss of human life and property recorded in human history was the Indian Ocean tsunami of December 26, 2004 which resulted in the death of over 2,30,000 human lives in several countries bordering the Indian Ocean. Tsunamis have always occurred in the geological past and they will occur in future as well. As earth scientists we should have better understanding of tsunamis in terms of how these waves impact various coastal geomorphologies and their environments, interaction of incoming waves with coastal sediments and rocks, processes of erosion and sedimentation, and lithology and paleontology of the sediments left on land by receding waves. Knowledge of historical and pre-historical records of tsunamis would enhance our understanding on the locations and frequencies of such events. This will improve risk assessment of potential locations of future tsunamis, thereby ensuing better preparation to avoid catastrophic consequences. However, identifying paleotsunami deposits and differentiating them from storm deposits are difficult because both events cause marine overwash on land. This ‘‘Paleotsunami’’ issue is significant in this regard and several papers highlight this problem. Some of the significant geological studies on paleotsunami deposits are Atwater (1987), Bryant et al. (1992), Clague et al. (2000), Nelson et al. (2004), Komatsubara and Fujiwara (2007). Geological records of paleotsunamis are rare, due to, as stated by Tappin (2007) ‘‘infrequency of events and/or poor preservation potential but alternatively may be due to