Rapid Changes in the Coastal Morphology of Amurang, North Sulawesi, Indonesia.

Fitria, J.; Gemilang, R.I.A.; Purnama, B., and Prasetyo, A., 2023. Rapid changes in the coastal morphology of Amurang, North Sulawesi, Indonesia. In: Lee, J.L.; Lee, H.; Min, B.I.; Chang, J.-I.; Cho, G.T.; Yoon, J.-S., and Lee, J. (eds.), Multidisciplinary Approaches to Coastal and Marine Management. Journal of Coastal Research, Special Issue No. 116, pp. 289-293. Charlotte (North Carolina), ISSN 0749-0208. Changes in coastal morphology can occur through long-term processes, such as sediment transport, and through short-term processes, such as those caused by earthquakes, storms, or tsunamis. On June 15th, 2022, a rapid change in coastal morphology due to a landslide happened in the coastal area of Amurang, North Sulawesi, Indonesia. Morphological changes and their triggers were analyzed through a comparison of post-slide and preslide bathymetry data, satellite imagery, and analysis of the soil layers. Based on the comparison of bathymetry data, the maximum change in seabed depth in the landslide area was 51 meters with a curvature shape on the rupture surface. The coastline has retreated about 150 meters inland with around 2.34 million m3 of material displaced. The results show that the landslides on the Amurang Coast that caused the rapid morphological change in the area were not triggered by hydro-oceanographical conditions, tectonic events, or volcanic events. They were triggered principally by the over-steepened slope and the ground soil's ability to support the additional weight of building embankments over a thick sediment layer. [ABSTRACT FROM AUTHOR]