Application of Hydro-Geochemical and Geo-Electrical Techniques to Identify the Impact of Tsunami in the Coastal Groundwater

Abstract

In general, the Coastal zones are dynamically active because of multivariate tectonic, fluvial marine and Aeolian geomorphic process which may vary in their dynamism with space of time. The tectonically active coasts show a greater influence on the land ocean interactive process. Tsunamis are ocean waves produced by earthquakes or underwater landslides. The word is from Japanese and means “harbor wave,” because of the devastating effects these waves have had on low-lying Japanese coastal communities. On 26th December 2004, Indian subcontinent experienced the most devastating tsunami in its recorded history. The phenomenon was triggered by a submarine earthquake located at 3.4° N, 95.7° E off the coast of Sumatra (Indonesia) with an intensity of 9RSU. Tsunamis are most often generated by earthquake-induced movement of the ocean floor. Such massive earthquakes only occur in subduction zones where two of the rigid tectonic plates that comprise the earth’s surface are converging, and one plate, usually composed of heavier oceanic material, dives beneath another, usually composed of lighter continental material. Aftershocks appear to be active over a 1300 Km section of the zone stretching from the Andaman Islands in the north to the earthquake epicentre below the northern tip of Sumatra, the seismic waveform data appears to indicate that only a 450 Km length of the subduction zone off northern Sumatra ruptured (Cumins & Leonard 2005). September 2004 AusGeo News article surmised, the greatest tsunami threat in the Indian Ocean appears to be posed by great subduction zone earthquakes of Sumatra. Studies of the Indian ocean tsunami has been carried out by several workers (Table 1), it reveals that the signature of tsunami has been clearly demarcated in the sediments and only a few studies were carried out in the groundwater. Still the impact of tsunami in the groundwater by both geochemical and geophysical methods has been carried out by very