Evaluation of Geochemical Signature in Soil Sampled from a 2004 Indian Ocean Tsunami-stricken Region in Aceh Province Located in the Western Part of Indonesia Using Scanning Electron Microscopy–Energy Dispersive X-ray (SEM-EDX) Spectroscopy and Its Compatibility with X-ray Fluorescence (XRF) Measurement

Abstract

Chemical elements in soil samples collected from the area struck by the massive Indian Ocean tsunami on 26 Dec 2004, were identified using scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM-EDX) to find out potential candidates for the geochemical signature of the 2004 Indian Ocean giant tsunami. All tsunami-affected soils were collected from three areas in Aceh Province, Indonesia, the worst stricken region by the Indian Ocean tsunami in 2004. SEM analysis showed that the damaged soil samples exhibited smaller particles and an inhomogeneous particle size distribution, which could be attributed to dissolved chemical element sedimentation after flooding by tsunami saltwater. Moreover, our findings revealed that the tsunami-affected soil samples contain many chemical elements – including marine signatures (Na, Ca, Mg, K, Al, and Si), terrestrial sources (Ti and Fe), and organic components (C and O). Organic elements detected as oxygen (O) dominated those impacted soils from the Aceh region, accounting for more than half of all samples, followed by carbon (C) and silica (Si). Furthermore, the concentration ratio of a series of elements in those impacted soils – namely, Si/Ti, Si/K, and Fe/Ti – demonstrates values that are exclusively different among the various elements evaluated in this work. The distinguishing difference in the concentration ratios of the elements matches well with X-ray fluorescence (XRF) measurement results. Therefore, the concentration ratios of the elements are good geochemical signatures of marine inundation for identifying the 2004 Indian Ocean tsunami soil samples in Aceh Province, Indonesia.