Geological slip rate study on Renun Segment of Sumatran Fault in Dolok Sanggul area, North Sumatra using UAV photogrammetry and DEMNAS

Abstract

Renun Segment is located in the center of the Sumatran Fault, parallel to the Famous Toba Lake Volcano. The fault cuts the thick, and vast Young Toba Tuffs (YTT) deposited ∼74,000 years ago during the supervolcano eruptions. It shows a series of noticeable dextral strike-slip offsets of the river valleys that deeply incised the tuffs. Our study will determine the geological slip rate in this location by measuring river-valley offsets in the Dolok Sanggul area using UAV photogrammetry and DEMNAS images. Detail morphology shows a fault lineament, monocline, and anticline structure. Three rivers about a hundred meters deep cross perpendicular to the fault line and have 585±83 meters dextral offset. This amount is only half of the other dextral offsets on the northern and southern parts of the site. Hence, the slip rate is also a half slower, approximately 7±1 mm/yr. This indicates that the other half of the slip budget is accommodated by the Samosir Fault in the center of Toba Lake.