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All Journal Ecotrophic, Journal of Environmental Science ILMU KELAUTAN: Indonesian Journal of Marine Sciences Journal of Environment Jurnal Geografi INTERNATIONAL JOURNAL OF ENVIRONMENT AND GEOSCIENCES INDONESIAN JOURNAL OF URBAN AND ENVIRONMENTAL TECHNOLOGY
Takahiro Osawa
CReSOS Unud
Agriculture, Biological Sciences & Forestry Chemical Engineering, Chemistry & Bioengineering Civil Engineering, Building, Construction & Architecture Earth & Planetary Sciences Education Energy Environmental Science Social Sciences Other

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Journal : Jurnal Geografi

 1 
Identification of Fault Zone in Bali Using GGMPlus Gravity and Alos-2 Palsar-2 Data Pratama, I Putu Dedy; Osawa, Takahiro; As-Syakur, Abd Rahman
JURNAL GEOGRAFI Vol. 15 No. 1 (2023): JURNAL GEOGRAFI
Publisher : Universitas Negeri Medan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24114/jg.v15i1.40772

Abstract

The local active fault in Bali has a small magnitude (M<5) but has destructive potential because it is very close to residential areas. Mapping the fault area on Bali is needed to identify the parameters of faults. This study used gravity data from GGMplus, topographic data from DEMNAS, and lineaments using ALOS-2 PALSAR-2 data. Validation and interpretation using the geological map of Bali and seismicity data. We interpret the subsurface using the gravity derivative method to identify the type of fault movement. Identify fault locations using lineament extraction from SAR data processed by directional filters. The composite image red-green-blue (RGB) for HH, HV, and VV polarization was used for automatic lineament extraction and then corrected manually. The results of the gravity method succeeded in identifying 29 of the 30 faults from the geological map of the Bali sheet and a new spot from PALSAR-2. Bali land has 12 thrust faults, 11 strike-slip faults and six normal faults. The image of PALSAR-2 (L band) has succeeded in making a fault lineament map for the Bali region. The lineament extraction results from PALSAR-2 obtained four new faults (Pesanggaran, Sepang, Tegal Badeng, and Banyuwedang), while four faults were not identified (Tampaksiring Fault, Plaga, Mambal, and Munduk-Rajasa). NE-SW dominates the strike directions, and the dip angles are 45-80 degrees. We propose 30 faults in Bali, including 26 defects from geological maps with changes in length and location shift and four new marks extracted from automatic lineament.Keywords: Remote Sensing, Earthquake, Derivative Gravity, Lineament, SAR 
Validation of Satellite Rainfall Product (GPM-IMERG) an Bali and Nusa Tenggara: A Comparison of Normal Seasons, El Nino and La Nina Events Tulistiawan, Putu Eka; Karang, I Wayan Gede Astawa; Osawa, Takahiro
JURNAL GEOGRAFI Vol. 15 No. 2 (2023): JURNAL GEOGRAFI
Publisher : Universitas Negeri Medan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24114/jg.v15i2.44967

Abstract

Bali and Nusa Tenggara are regions where monsoonal wind changes and strange interactions between the ocean and atmosphere influence rainfall. The purpose of this research is to evaluate Integrated Multi-Satellite Retrievals for GPM (IMERG) rainfall data using in-situ observations from Bali and Nusa Tenggara, Indonesia, while considering seasonal variations and the El Nino-Southern Oscillation (ENSO) phenomenon. The study combines rainfall data from synoptic stations with rain gauge measurements over ten years, from January 2012 to December 2021, to obtain more accurate verification results. The study's findings indicate that, apart from the transitional seasons, IMERG data provides substantial estimates of monthly rainfall accumulation with low error values for both light and heavy rainfall. The study also reveals that the islands' complexity and topography can impact each province's validation values. The verification results show excellent accuracy in flat terrain areas and moderate elevations, while performance decreases in regions with high altitudes. These findings are significant because IMERG data can estimate rainfall for regions lacking monitoring stations during specific seasons and active ENSO conditions. Thus, this information can serve as a valuable tool to address the issue of data unavailability in hard-to-access areas and contribute to optimizing water resource management and weather-related disaster mitigation. Keywords: Validation, Rainfall, IMERG, ENSO
Co-Authors Abd. Rahman As-syakur Arbani, I Made Dwi Ayu Margaworo Pamungkas Chonnaniyah, Chonnaniyah Dwi Puspa Arini Feronika, Feronika Gathot Winarso, Gathot I Gede Hendrawan I NYOMAN MERIT I Wayan Arthana I Wayan Gede Astawa Karang I Wayan Nuarsa I Wayan Sandi Adnyana Ippah, Imro’atul Kuncoro Teguh Setiawan, Kuncoro Teguh MASITA DWI MANDINI MANESSA, MASITA DWI MANDINI Novi Susetyo Adi, Novi Susetyo Pertiwi Jaya, Ni Made Prasetyo, Otniel Stefen Adi Pratama, I Putu Dedy Putu Hadi Wiguna, Pande Rosid, Mohammad Syamsu Sholihah, Qomariatus Suardana, A.A. Md. Ananda Putra Supardjo, Harsono Tulistiawan, Putu Eka Wati, Kadek Setiya Wikanti Asriningrum, Wikanti