Geological evidence of predecessor of the 2018 Tsunami in Palu, Sulawesi, Indonesia

Abstract

Following the 2018 Palu tsunami event in Central Sulawesi, Indonesia, the geological evidence of paleotsunami in Palu, was investigated to extend the historical record of past tsunamis in this area. A geological survey was conducted in Talise Beach, Palu City, at the southern end of Palu Bay. The stratigraphy sequence from the outcrop profile in Talise Beach showed three clear paleotsunamis. These paleotsunamis are distributed widely and can be traced along 1 ​km parallel to the beach, and each layer is characterized by poorly sorted sand deposited on the paleosoil. The boundary between the sand layers and paleosoils is sharp and erosional. The sedimentological and foraminifera analyses support the identification of paleotsunamis. Based on the radiocarbon dating, it was interpreted that these three paleotsunamis occurred in the 17th, 18th, and 19th century. This first paleotsunami study in Palu, not only provided geological evidence of paleotsunamis, and extended the tsunami record in Palu, but also served as an essential start for tsunami geology study in Palu as the tsunami sources in this area are complex.