East Nusa Tenggara is a region in Indonesia which included in the category of hazard prone to earthquakes, because it is flanked by two earthquakes zones, (subduction zone at the south and back arc trust in the north). It is also vulnerable to earthquake disasters because of high population density. These conditions would threaten the safety of lives and property of the population, so it needs to be research to analyze the level of earthquake hazard and vulnerability in East Nusa Tenggara. For identification of the level of hazard and the vulnerability of the earthquake in this study using two factors: the danger factor with indicator Peak Ground Acceleration, vulnerability factors with indicators of population density districts in East Nusa Tenggara. The calculation of the value of PGA use attenuation function of Fukushima and Tanaka. From the calculation of the data obtained that has a very high earthquake hazard is in Ende and Alor district, while the district has a very high risk of vulnerability is in Sikka, Sumba Barat Daya and Sabu Raijua.

Bali is one of the areas prone to earthquake and tsunami as being at the junction of two plates, namely the Eurasian plate and the Indo-Australian plate is located in the south of Bali and back arc trust zones are located in the North of Bali. We need research on the potential dangers of earthquakes and tsunami in Bali are based on the value of seismicity which is interpreted by the value of b and a. This study uses earthquake data on the coordinates 6?-11? SLand 114?-116? EL with 339 data that was processed using Zmap in order to obtain the value of b at 1.57 ± 0.008 and the value of a is 10.6 and maximum magnitude of 7.1 Mw. From mapping the values ??of b and a known area that has the highest value of b and a lies in the sea area to the south of Bali, Karangasem and Buleleng to the northern region of Bali. Furthermore, for mapping the tsunami in Bali using the TOAST application obtained tsunami prone areas of Bali, Kuta Beach, East Buleleng and Karangasem.

Research has been carried out to identify the presence of subsurface water in Selulung Village, Kintamani District, Bangli Regency using 2D geoelectric methods. The work process of this research is the first to collect data directly by using a geoelectric device with Wenner configuration. Electric currents are injected from the surface to the subsurface through the current electrodes which are put on the earth's surface. The collected data is then processed using the Res2Din software version 3.71.118. The software results in the form of 2D images are direct lateral images of subsurface structures. From the three trajectories identified, namely at the coordinates  8°12'18.7"S 115°16'08.3"E the lowest resistivity value was 178 Ohm m with a depth of 10 m which was thought to be a rock layer with surface water content. On line 2 at coordinates 8°12'16.1"S 115°16'09.7"E the resistivity value is 6 ohm.m up to 660,000 ohm.m, the maximum depth obtained is 24 m. This line is thought to be a water-bearing layer because the value of resistance is low. Line 3 which is in the coordinates 8°12'16.3"S 115°15'50.0"E the distribution of resistivity values varies from 42 - 9,400 Ohm m.

This study aims to determine the value of the gravity anomaly in the Bali region, identify the fault structure in the Bali region using gravity interpretation and analyze the relationship between gravity anomaly and seismicity in the Bali region. The data used is secondary data, namely satellite gravity anomaly data obtained from the topex website and earthquake data obtained from the Indonesian Agency for Meteorological, Climatological, and Geophysics (BMKG) catalog. Data processing in this study was done using gravity and Second Vertical Derivative (SVD) methods. We used Surfer15 software, Oasis Montaj, and the Generic Mapping Tool (GMT). The results of the complete Bouguer anomaly map show the anomalous value of the study area between 10-220 mGal, regional anomaly 40-190 mGal, and the residual anomaly between (-120)-60 mGal. Judging from the SVD contour map that has included earthquake data in the Bali region for the 2008-2020 period, the type of fault in the Seririt Fault, Tejakula Fault, and Fault around Mount Agung is a thrust fault. Judging from the value of the coefficient of determination, it shows that 99% of the seismicity value is influenced by gravity anomaly. The higher the value of the gravity anomaly, the higher the seismicity value.

Telah dilakukan penelitian pemodelan 3D struktur bawah permukaan Gunung Anak Ranakah dan sekitarnya. Penelitian ini bertujuan untuk membuat peta serta menentukan nilai anomali bouguer lengkap, anomali regional, anomali residual, nilai densitas bawah permukaan serta membuat model 3D struktur bawah permukaan. Data yang digunakan merupakan data sekunder yaitu data anomali gravitasi satelit yang diperoleh dari website Topex. Pengolahan data dalam penelitian ini menggunakan metode gravitasi. Pada metode ini akan dilakukan koreksi gravitasi, membuat peta anomali bouguer lengkap, melakukan analisis spektrum, melakukan pemisahan anomali regional dan residual menggunakan filter butterworth serta melakukan inverse modelling dengan menggunakan software ZondGM3D untuk membuat model 3D struktur bawah permukaan. Hasil peta anomali bouguer lengkap menunjukkan nilai anomali  daerah penelitian antara 134,6-209,3 mGal, anomali regional 147,4-205,9 mGal dan anomali residual antara (-12,8)-11,0 mGal. Hasil inverse modelling menunjukkan bahwa struktur geologi bawah permukaan Gunung Anak Ranakah dan sekitarnya memiliki rentang densitas antara 1,2-3,0 g/cm3, sehingga dari rentang nilai densitas batuan dapat diperkirakan struktur geologi bawah permukaan Anak Gunung Ranakah dan sekitarnya terdiri dari batuan soil (1,2-2,3 g/cm3 , andesit 2,40-2,80 g/cm3) dan basalt (2,70-3,0 g/cm3).