Subsurface Model Of Mt. Sinabung Using The GGM-Plus Satellite Gravity Data And Deconvolution Euler

Mt. Sinabung in Karo Regency, North Sumatra Province, with an altitude of 2450 meters above sea level, became active again in 2010 after a break in volcanic activity for ± 300 years. Since the eruption in 2010 until now, eruptions are still ongoing periodically. The aim of this research is to obtain a model of the subsurface density distribution of Mt. Sinabung. Modeling was carried out using GGM-Plus 2013 satellite gravity data and ERTM2160 topographical data. Bouguer correction and terrain processing use an average density of 2.67 g/cc. After that, the anomaly was separated by using the moving average. Residual anomalies were then analyzed using Euler deconvolution. The results obtained are the existence of a fault structure on the west and three layers of rock obtained which consist of the basement with a density of 2.8 g/cc 3 – 3.3 g/cc, then Toba pyroclastic deposits with a density 1.8 g/cc – 2.3 g/cc and limestone deposits with a density of 2.4 g/cc – 2.7 g/cc

Meteorological Drought Analysis Using The Theory Of Run Method In Lusi Watershed, Central Java

Reduced water reserves can be caused by decreased rainfall. During the dry season along the Lusi River, Central Java, water quantity decreased, so that the area along the Lusi River passes in drought conditions. This study aims to determine the longest duration of drought and the largest cumulative number of droughts, in the Lusi watershed for a ten-year period. The level of drought in the Lusi watershed was analyzed using the Theory of Run method. The results obtained were the longest drought duration of 9 months and the largest cumulative drought amount of -486 mm and the Lusi watershed was classified as a meteorological drought

Determination of Vertical Deflection Based on Terestrial Gravity Disturbance Data (A Case Study in Semarang City)

Vertical deflection can be determined by geometrical and physical measurement. In geometrical way, vertical deflection is obtained by comparing astronomical coordinate and geodetical coordinate. In physical way, vertical deflection can be computed from gravity measurement. In the past, vertical deflection was computed from gravity anomaly data. Gravity anomaly data measurement is difficult because it need reduction of gravity from surface of the earth to the geoid using orthometric height from spirit level measurement. In modern era, gravity anomaly data may be replaced by gravity disturbance data whose only required gravity and GNSS (Global Navigation Satellite System) measurement. This research aims to determine vertical deflection in Semarang City from terrestrial gravity disturbance data. The gravity data were measured in March of 2016. Formula of Vening Meinesz that usually used for vertical deflection was replaced by new formula that generated from derivation of function of Hotine. Applying gravity disturbance gave vertical deflection of east-west component that were vary from -1.2” to 12.2” while north-south component were vary from -4.2” to 4.2”. Comparing vertical deflection as computed from terrestrial data to as computed from EGM2008 coefficients showed conformity in shape and values. It was concluded that derivation of function of Hotine could be applied for vertical deflection determination from gravity disturbance

Data validation of gravity field and satellite data using correlation and coherence method

Satellite data is frequently used as an initial study of a research area for its easy to access feature as well as its improving quality. One of the available satellite data is geopotential data. Satellite data is commonly used to be correlated to the topography data. In this research, satellite data is used as the database of validation in a research area. Valid measuring data is highly required, so that the qualified data is obtained for further process. To identify the validity, additional other QC is required than the existing QC which in 1D. The validation method which applied are correlation and coherence method. The distribution of correlation and coherence values show  asimilirity or compatibility of field data with satellite data. The correlation method was calculate in 2D and the coherence in 1D. Correlation calculation of field data produces high correlation and coherence value to satellite data as much as 0.7 to 0.95 so that it could be identified that acquisition and data processing have been carried out correctly

Drought Analysis On Ngawi District West Jawa Using The Standardized Precipitation Index (Spi) Method Based On Rainfall Data 2012 To 2021

Changes in Pacific Ocean and Indian Ocean temperatures can trigger climate change, one of which is El-Nino. Ngawi Regency, East Java, Indonesia is one of the areas frequently affected by drought, which is thought to be caused by El Nino. This research was conducted to determine the distribution of drought in the Ngawi district. The method used is the Standardized Precipitation Index (SPI) and the data used is monthly rainfall data. The mapping uses ArcGIS 10.5 software with IDW (Inverse Distance Weight) interpolation. The results obtained are that the maximum drought conditions in Ngawi Regency occurred in 2015, with a very dry category. The area with the highest frequency of droughts is Jogorogo District with 36 times. The ENSO correlation value for drought is 5.1%

Identification of Sediment Formation Based on Magnetic Content and Element Composition of Mud Volcano in Sangiran Sediment using VSM and X-Ray Fluorescence

Based on trace geological history and several studies, the Sangiran mud volcano provides insight into the geology and hydrology of the region, aquifer system in the basin, groundwater flow patterns and characteristics, rock lithology, hydrogeology condition, and saltwater trap mapping. Related to these conditions, studies were conducted on the magnetic content and composition of the major oxide compounds in the Sangiran sediments. Sample analysis was based on geochemical methods. The methods consist of frequency dependent magnetic susceptibility and vibrating sample magnetometer (VSM) analysis. Geochemical analyses using x-ray fluorescence (XRF) analysis have been conducted and various elemental grades have been determined. VSM results confirm that the magnetic content of Sangiran sediments is partly dominated by Fe (17.66 percent) contained in hematite (Fe2O3). At the same time, the samples of Sangiran sediment were enriched by Si, Fe, Al, Ca, Cl, Ti, and K according to XRF measurements. The samples exhibited the highest Si and Fe concentrations in samples T1 (Si is 29.48 percent and Fe is 13.66 percent) and T7 (Si is 24.95 percent and Fe is 12.01 percent). Meanwhile, in the T4 sample, the highest concentrations were Si and Ca, 23.45 percent and 13.45 percent, respectively. Retrieved from the magnetic susceptibility measurement, this paper confirm that Fe content is one of the components of volcanic ash in the Sangiran sediment.DOI: 10.17977/um024v8i12023p00

Estimasi Ketebalan Sedimen dan Kedalaman Diskontinuitas Mohorovicic Daerah Jawa Timur dengan Analisis Power Spectrum Data Anomlai Gravitasi

Gravitation anomaly research had been done to predict the depth of sediment. The gravitation research covered East Java from north coast to south coast, Indonesia. By using power spectrum method the average of sediment depth could predicted. Power spectrum method based on FFT theorem. A Short wavelength signal was correspond to narrow source and a long waveleght signal corresponds with shallow source. The power spectrum result was two discontinuities. The depth of narrow discontinuity is 2,7 km and 25,6 for the shallow continuity. The shallow discontinuity predicted as Mohorovicic layer

Melacak kelurusan sesar dengan metode turunan vertikal kedua data anomali bouguer

Telah dilakukan penyelidikan geofisika dengan metode gaya be rat di daerah Batur. Penyelidikan ini dimaksudkan untuk melacak alur sesar yang terdapat di bagian tengah kaldera Batur. . Pengmmpulan data dengan menggunakan Gravimeter Laonsta & Romberg G.928. Alat tersebut berguna untuk men!Kukur varlasi harga g di daerah pen+ litian. ailakukan koreksi pasang dvift, udara bebas. koreksi Bouguer dan topografi diporoleh harga aaothali Bouguer. Yang kemudian dibuat konturnya. Dengan metode turunan vertikal kedua diperoleh :3e:Jar yang dicari. Yang ternyata berarah relit: if tenggara laut ke timur laut. ABSTRACT A geophysical survey using gravity method has been carried out in Batur. This survey had an order to get some information about the straightness of fault. Data collecting in this area was done by using Gravimeter Lacosta & Romberg G.928. Gravimeter was used for .measure gravity variation on earth. A lot of correction was done. With tidal correction, drift correction, free air correction, Bouguer correction and terrait correction we found the value of anomaly Bouguer. Based on these anomaly value a contour map was made. By using second vertical derivative method, straightness of fault were obtained. The straightness of fault is on south-east north-west and turn to north-east

UJI NILAI TAHANAN JENIS POLUTAN AIR LAUT DENGAN METODE OHMIK DAN GEOLISTRIK TAHANAN JENIS SKALA LABORATORIUM

Geoelectric method and ohmic method used to investigate sea water intrution (salinity) in aquifer layer.Resistivity data aquisition for 3 layer model and 3 concentration of salinity was in laboratory scale. By comparing resistivity data before and after adding sea water we get resistivity value for each layer. The research result is decreasing of resistivity value for increasing salinity concentration