A study on pre- and post-tsunami shallow deposits off SE coast of India from the 2004 Indian Ocean tsunami: a geochemical approach

Abstract

A study was made on samples from one core collected immediately after the December 2004 Asian tsunami to know the geochemical nature of the offshore tsunami sediments. The core sample was analyzed for sediment grain size, CaCO 3 , organic carbon (OC) and major elements (SiO O 5 , MnO). The results indicate that the core sample can be divided into two parts: (1) upper 0-25 cm, interpreted to be deposited after tsunami (AT), and (2) lower 25-45 cm, interpreted as before tsunami (BT) as evidenced by the sandy nature AT with fluctuating CaCO 3 contents. The AT part is devoid of OC suggesting that the sediment could have been transported to deeper regions along with the finer particles. Major elements such as SiO 2 , TiO 2 , CaO indicate high values than the other elements in AT part than in the BT part. The BT part contains Al rich alluvium mud associated with finer mud and organic particles. An analysis of the correlation matrix indicates the possible source of elements and transport of heavy minerals in the AT part than the BT part. The overall results suggest that the sediments could possibly have two different origins.

The recorded evidence of AD 1755 Atlantic tsunami on the Gibraltar coast

“…Therefore, the energetic event that Unit 2 could generate would be the 1755 tsunami. Evidence of similar deposits have been described for India where sand deposits without organic matter content and even material dragged from the continent by the backwash (Srinivasalu et al, 2010) have been recorded.…”

Identification and characterization of tsunami deposits off southeast coast of India from the 2004 Indian Ocean tsunami: Rock magnetic and geochemical approach

“…The recent study of Elakkiya et al (2013) also describes the assemblage of foraminifera, ostracoda, and their distribution (species including Ammonia beccarii, Globigerina bulloides, Quinqueloculina sp., Spiroloculina orbis, Propontocypris bengalensis, Propontocypris crocata and Phlyctenophora orientalis) in the study area (Nagapattinam), suggesting that these species have been brought by the high energy tsunami waves (2004 IOT deposit). The previous studies (Srinivasalu et al 2010;Jonathan et al 2012) provide the supporting evidences of the source of sand deposits in zone II. The zones I and III indicate the domination of clay and silt as compared to zone II, suggesting suspension/deposition of finer particles and reworking of modern process in the near shore environment before and after the major event.…”

“…This will help to compare and study the rock magnetic and geochemical nature of sediments of the 2004 tsunami deposits as well as paleo-tsunami deposits near the coastal/lagoon regions along the SE coast of India. Moreover, in Nagapattinam town (the study area), the inundation by tsunami waves was up to ∼800 m compared to the other parts of the coastal areas (Yeh et al 2006) and the maximum damage (in Tamil Nadu state) in terms of economic and human losses were reported from this region (Srinivasalu et al 2010).…”

“…Various aspects of the 2004 IOT onshore deposits on the east and west coasts of India were reported by several researchers (Altaff et al 2005;Earnest et al 2005;Jayakumar et al 2005Jayakumar et al , 2008Kumaraguru et al 2005;Nagendra et al 2005;Neetu et al 2005;Narayan et al 2005;Srinivasalu et al 2009;Anilkumar et al 2006;Chaudhary et al 2006;Hussain et al 2006Hussain et al , 2010Mascarenhas 2006;Shanmugam 2006Shanmugam , 2012Yeh et al 2006;Babu et al 2007;Bahlburg and Weiss 2007;Mascarenhas and Jayakumar 2008;Pari et al 2008;Vijayalakshmi et al 2010;Jayakumar 2012). However, studies on offshore tsunami deposits in India are limited (Srinivasalu et al 2010;Jonathan et al 2012) and many case studies are necessary to develop a depositional model. Though, tsunami events are rare in nature, scientific documentation helps in coastal management and mitigation measures for the future.…”

“…Ranjan et al (2008) and Srinivasalu et al (2008) evaluated the metal enrichments from the 26 December 2004 tsunami sediments along the SE coast of India. Srinivasalu et al (2010) have studied the pre-and post-tsunami shallow deposits off SE coast of India from the 2004 IOT using the geochemical approach. In India, magnetism has been used in environmental studies with strong implications in anthropogenic pollution monitoring (Alagarsamy 2009;Sangode et al 2010;Venkatachalapathy et al 2010Venkatachalapathy et al , 2011aVenkatachalapathy et al , b, 2013Blaha et al 2011;Sandeep et al 2011), climatic variations and depositional mechanisms (Shankar et al 1994a(Shankar et al , b, 1996Sangode et al 2001Sangode et al , 2007Chauhan et al 2004;Kumar et al 2005;Kumaran et al 2005;Rao et al 2008;Dessai et al 2009;Dewangan et al 2013).…”