Utilisation of Seismic Refraction Method in Producing Shale Topography Map of Sungai Batu Ancient River

Abstract

Geophysical methods have been widely used in archaeological prospecting for decades. This is for the fact that the methods provide a great deal of information for archaeologist to determine buried evidences beneath the surface. Geophysical methods are also cost effective, covering much larger area at relatively lower costs, compared with the conventional archaeological probing techniques. The methods are also non-destructive and non-invasive, keeping archaeological sites entirely undisturbed after survey. Several geophysical methods including resistivity, magnetic, gravity, ground penetrating radar and electro-magnetic are usually implemented to map out the archaeological evidences. It is often believed that the seismic refraction method may not be suitable when looking for anomalies of archaeological remains. However, since the purpose of this study is to delineate the boundary of shale to locate the ancient river, seismic refraction can give the very much desired result. The study was conducted at Sungai Batu, Kedah, Malaysia, which is famously known for its archaeological sites, including an ancient international entrepot. The discovery of jetty remains within the study area is also indicative of the existence of ancient river. The results obtained showed that the shale (suspected riverbed) are characterised with P-wave velocity of > 1822 m s–1. The suspected ancient river was determine based on a ravine shape that observed. It is believed that shale which is found at a depths of > 15 m is categorised as ancient river bed. It is concluded that the ancient river was probably flowing from North-South direction towards East.