The Impact of Landslides in Reclamation Areas from Stone Crusher Production Residue Materials in the Tsunami Event in the Sulawesi Earthquake on September 28, 2018

Sulawesi earthquake disaster followed by a tsunami on September 28, 2018 still leaves several big questions, namely the type of normal strike slip fault that rarely causes a tsunami, the very short tsunami arrival time of around 2-5 minutes and the bay area that should rarely be hit by a tsunami. Several previous studies have provided several hypotheses that the tsunami was caused by an underwater landslide or vertical deflection of the seabed due to the super shear movement. This study conducted a study of the impact of Stone Crusher factories residual production based on a field survey and supported by secondary data from previous researchers on the tsunami disaster after the strong earthquakes. The results of the field survey showed an area of ​​around 40 Ha that collapsed on the surface, most of which was a pile area of ​​residual Stone Crusher production on the West coast of Palu Bay. This area stretches around 20 km covering the areas of Palu City and Donggala Regency. Based on the data, there are around 240 Stone Crusher factories permits, from 42 companies that have operated on the West coast of Palu Bay, 19 operating in the Donggala Regency area and 23 in the Palu City area. Some of these mines have been operating since 2000. Around 20-30% of the total production is the remaining production in the form of landfill that is transported from the factory location to the coast and stockpiled around the loading area of ​​the Stone Crusher results before being sent to Kalimantan and other islands. One Stone Crusher unit annually produces around 300,000 m³ of waste in the form of landfill. If the average of 40 Stone Crusher factories that have been producing for 20 years, the waste output is around 200,000,000 m³. This mass of material if it experiences a landslide after the earthquake is significant enough to move the mass of water to cause a tsunami that spreads to the East side of Palu Bay. Secondary data in the form of photos and videos shortly after the earthquake shows a white whirlpool and the spread of tsunami waves from the coast towards the middle and there is a wave direction parallel to the coastline. This indication shows a landslide from the reclaimed landfill from the remaining stone crusher production that was stockpiled on the West coast of Palu Bay. In addition to the impact on disaster vulnerability, mining activities of Stone Crusher factories in the form of Stone Crusher factories also have an impact on the surrounding natural environment in the form of pollution of settlements, damage to vital infrastructure, marine biota, human health and livestock. Comprehensive and sustainable efforts are needed to overcome the negative impacts of Stone Crusher factories mining activities together from all stakeholders.