The sediments of Lake Singkarak and Lake Maninjau in West Sumatra reveal their earthquake, volcanic and rainfall history

Natural hazards such as earthquakes, volcanic activity, and heavy rainfall causing floods and debris avalanches are common phenomena in many tropical settings, including the island of Sumatra, located in the Indonesian archipelago. To enhance our understanding of the recurrence of these often destructive events, we studied the sedimentary infill of two lakes in the Padang highlands, West Sumatra. This includes Lake Singkarak, a tectonically-formed lake located on a step-over of a major strike-slip fault system (the Sumatran Fault), and Lake Maninjau, a caldera lake. Both lakes are located similar to 300 kmfromthe Sunda subduction trench and surrounded by steep slopes and a chain of active volcanoes. Hence, considering their unique tectonic setting, these lakes may potentially record awide range of natural hazards that affect the region. A combination of seismic-reflection profiles and short sediment cores revealed that both lakes indeed record various types of natural hazards, each with their own sedimentary response to a specific type of event. Lake Singkarak can be used to study past floods and major debris avalanches in addition to high-magnitude megathrust earthquakes, while traces of past intraplate earthquakes have been identified in both lakes. Furthermore, we argue that Lake Singkarak is an ideal recorder of volcanic activity in the region, while Lake Maninjau itself can pose a volcanic hazard to its surroundings as demonstrated by potential activity of the volcano below the lake. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The study found that the two lakes in West Sumatra, Lake Singkarak and Lake Maninjau, are able to record various natural hazards such as floods, debris avalanches, earthquakes, and volcanic activity that impact the region. These lakes, in their unique tectonic setting, show specific sedimentary responses to past natural disaster events.