PEMETAAN ZONA TINGKAT BAHAYA BENCANA GEMPABUMI DAERAH KOTAAGUNG DAN SEKITARNYA BERDASARKAN KARAKTERISTIK DINAMIS TAPAK LOKAL; EARTHQUAKE RISK ZONE MAPPING BASED ON LOCAL SITE DYNAMIC CHARACTERISTICS IN KOTAAGUNG AND IT IS VINICITY

Narendratama, Raditya, Wiwit Suryanto

2016 | Skripsi | FMIPA

Indonesia, a country with earthquakes risks because it is located at the confluence of tectonic plates between Eurasian Plate and Indo-Australia Plate. One of the city that is prone to earthquakes is Kotaagung, Lampung Province. According to seismicity research which has been conducted, local geological conditions affect the vibrations propagating from earthquake source. The objective of this research is to determine the dynamic characteristics of the ground in mapping earthquake hazard areas in Kotaagung and its vicinity. Research data from microtremor measurement and seismicity information. Nakamura methods (1989) or HVSR method (Horizontal to Vertical Spectral Ratio) compares the horizontal and vertical components to determine the characteristics of the soil dynamics which is influenced by subsurface geological conditions. Nakamura method is to determine the value of the dynamic characteristics of the soil, Which are the natural frequency f0 0.36 – 10.88 Hz and amplification factor A0 0.73 – 4.14. Both value is used as inputs to determine the value of other soil characteristics such as dominant period T0 0.07 – 3.23, quality factor 0.16-3.94, seismic vulnerability index Kg 0.22 – 43.95, the thickness of sediment layer h 2.39 – 366.57 m, the peak ground acceleration on surface ? 24.98 – 192.91 gal, and ground shear strain ? 0.003 – 2.19 mgal second. The value of h and ? can be determined by the seismicity data such as earthquake information and the S wave velocity at 30 meters depth. Earthquake hazard zone is divided into three categories: low, medium, and high risk rate. Low zone risk is located in Pulau, Jambu and North Kotaagung. Medium risk zone is located in Pajajaran, and Center-South Kotaagung. The hirgh risk zone is located in Belu, Teratas, and East Kotaagung.

Kata Kunci : Microtremor; Kotaagung; HVSR; Seismicity