Investigation of Landslide in the Ulu Manna, South of Bengkulu District Based on Horizontal to Vertical Spectral Ratio Inversion

The value of ��30 as an important parameter in predicting the movement of seismic waves. Data ��30 can be
obtained from microtremor data and ultrasound data. This research aims to identify avalanche zones based on HVSR
inversion in Ulu Manna District, South Bengkulu in mitigating landslide disasters in the area. The amount of data used
was 30 microtremor data measurement points. Microtremor data was processed using Geopsy software which was analyzed
using the HVSR system, HVSR inversion was carried out using Hv-Inv software and value of ��30 compared to a value
of ��30 from USGS data to obtain accurate results. The results of microtremor data research showed that the value of ��30
in Ulu Manna District ranged from 243,96 m/s - 766,84 m/s and the soil site class was dominated by class D with medium
soil texture which was classified as a high seismic vulnerability zone. The ratio of ��30 from the results of microtremor
data and USGS topographic models varies around 0.56 - 1.76. This shows that the results of data ��30 microtremors are
different, but not much different in value from data ��30 USGS. Based on the results of microtremor data research
conducted in the research area coupled with the results of rainfall data (2013 - 2022) in Ulu Manna District which is very
high with a total of 3854 – 5513 mm per year, Ulu Manna District is classified as an area prone to potential landslides.