Subsurface Images Shed Light on Past Tsunamis in India

Abstract

The 2004 Indian Ocean tsunami caused massive devastation and left a lasting impact along many of the major coastal regions in South Asia, including the coast of Tamil Nadu, a state in the southeastern tip of India. Following the event, sand deposits draped the low‐lying areas and buried the muddy sediments of the coastal plain [Babu et al., 2007; Srinivasalu et al., 2007]. In addition, erosional features related to the tsunami, such as channels and scarps, have been observed along many parts of the coast (Figure 1a). This tsunami, along with a recorded history of intense monsoons, has highlighted the need for focused research on the role of extreme events in shaping the geological character of India's coastal plains.

Evidence for a mid-Holocene tsunami deposit along the Andaman coast of Thailand preserved in a mangrove environment

“…before present using OSL (Nair et al, 2010). Although chronological similarity is perhaps the least convincing evidence, the similar ages across the Indian Ocean support a tsunami origin rather than a storm origin for this mid-Holocene event horizon.…”

“…4) Unit tIII is a potential far-field equivalent of a recently recognized tsunami event deposit on the southwestern Indian coast ca. 3710 years before present (Nair et al, 2010). 5) Addressing the original hypothesis, mangrove environments are potential sites for preserving paleotsunami sediment and should be considered as viable archives elsewhere as scientists seek to reconstruct the history of past tsunami events.…”

Morphodynamics and Geological Legacy of Berm Scarps Along Non-Tidal (Ukraine) and Microtidal (The Bahamas) Coasts

“…1B, 2D) serve as fertilizer for colonizing plants, promoting dune stabilizaton. As materials suitable for radiocarbon dating, organic debris also provide general chronological control, complementing the optical chronology of overlying sediments [3,12,14,15].…”

“…Whereas gravel beaches may have multiple berms and scarps, sandy coastlines exhibit a single scarp within the berm (foreshore) region [2,22,23,27]. This steep erosional feature may have variable longshore extent and is typically generated by wave erosion during storms, with subordinate mechanisms that include increased wave activity during spring high tides and seiches, ice scour, and tsunamis [12,15,22,23,27]. In contrast to dune scarps, these morphological elements receive less attention in the literature largely due to their ephemeral nature as surface features [3,8,20,23].…”