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All Journal Natural B Jurnal Fisika : Fisika Sains dan Aplikasinya Wahana Fisika : Jurnal Fisika dan Terapannya
Harti Umbu Mala
Universitas Pattimura
Astronomy Earth & Planetary Sciences Electrical & Electronics Engineering Engineering Environmental Science Materials Science & Nanotechnology Physics

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Microtremor and Geolistrik Resistivity Study Around the Trans Timor Primary Arterial Road for Disaster Mitigation Harti Umbu Mala; Adi Susilo; Sunaryo Sunaryo
Natural B, Journal of Health and Environmental Sciences Vol 3, No 1 (2015)
Publisher : Natural B, Journal of Health and Environmental Sciences

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (781.399 KB) | DOI: 10.21776/ub.natural-b.2015.003.01.4

Abstract

The research on microtremor and geoelectric resistivity around Trans Timor Primary Artery Road to disaster mitigation, has been done. The aims of this research were to obtain the Peak Ground Acceleration (PGA) value, the soil dominant frequency, seismic vulnerability index and to estimate the thickness of sediment layer. Microtremor data collection was done by using a three-component seismometer, DS-4A feedback short-period, at 52 points with 250 m interval. Dominant frequency and amplification factors were obtained by using curve analysis method, horizontal to vertical spectral ratio (HVSR). The PGA value was calculated using Kanai empirical equations, where the data of dominant period were obtained from the inversion of frequency values while the parameters of the earthquake were based on seismic events in the last 50 years, from 1963 to 2013 with magnitude of ≥ 3. Geoelectric measurements were conducted using a Resistivity-meter OYO, based on Wenner Schlumberger configuration and it was divided into two lines, with length of 400 m each.  From the results obtained by PGA value is ranged between 80 and 500 gal with level of risk moderate two to very large one. The distribution value of the soil dominant frequency was 0.62 Hz-18.27 Hz, while the distribution of the seismic vulnerability index ranged from 0.21 to 21.83. The type of soil is dominated by clay and alluvium as top soil and its thickness varies from 10 m to 50 m, strengthened by limestone as bedrock. 
IDENTIFIKASI POLA DISTRIBUSI STRESS COLOUMB PADA GEMPABUMI 2 AGUSTUS 2019 DI TUGU HILIR, INDONESIA Umbu Harti Mala; Juliany Ningsih Mohamad; Bernandus Bernandus; Valentinus G. V. Putra
Jurnal Fisika : Fisika Sains dan Aplikasinya Vol 5 No 1 (2020): Jurnal Fisika : Fisika Sains dan Aplikasinya
Publisher : Universitas Nusa Cendana

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (233.123 KB) | DOI: 10.35508/fisa.v5i1.2381

Abstract

Abstrak Penelitian ini bertujuan untuk mengidentifikasi pola distribusi perubahan stress coulomb yang dapat digunakan untuk melihat gempabumi susulan yang terjadi dalam jarak dan dalam rentang waktu yang dekat. Penelitian ini menggunakan data gempabumi yang terjadi pada 2 agustus 2019 dengan Mw 6,9 di Tugu Hilir, Indonesia, pada koordinat 104,825 BT dan 7,267 LS dengan kedalaman 52,8 km (USGS) memiliki mekanisme fokus (Strike, dip, rake) adalah (201°, 49°, 54°). Data ini kemudian diolah dengan menggunkan software coulomb 3.3 pada matlab. Dari hasil penelitian didapatkan bahwa gempabumi ini gempabumi ini memiliki peningkatan stress coulomb (≤ 1,0 bar) berarah timurlaut-baratdaya dan merupakan daerah gempabumi susulan terjadi. Sedangkan daerah penurunan stress coulomb (≤ -1,0 bar) berarah barat-laut tenggara. Kata kunci: gempabumi, perubahan stress coulomb, coulomb3.3, USGS, Tugu Hilir. Abstract This research aims to Identifed the distribution coulomb stress changed that can be used to seesthe subsequent earthquake that occurs within a short distanceand time span. This research uses earthquake data on 2 August 2019 with Mw 6.9 in Tugu Hilir, Indonesia, at 104.825°E and 7.267°S, with 52.8 km depth (USGS). The focus mechanism (strike, dip, rake) is (201°, 49°, 54°). This data prosessed by using Coulomb 3.3 software in MATLAB. The result found that this main earthquake had an increase coulomb stress changed (≤ 1.0 bar) in the northeast-southwest and was a subsequent earthquake area. Whereas the area of decrese of coulomb stress changed (≤ -1.0 bar) in the northwest-southeast. Keywords: earthquake, coulomb stress changed, coulomb 3.3, USGS, Tugu Hilir
Arah Penyebaran Stress Coulomb pada Batuan akibat Gempabumi Kairatu 26 September 2019 Harti Umbu Mala; Juliany N. Mohamad
Wahana Fisika Vol 5, No 1 (2020): June
Publisher : Universitas Pendidikan Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17509/wafi.v5i1.24500

Abstract

Penelitian ini bertujuan untuk mengetahui arah penyebaran stress batuan yang diakibatkan oleh gempabumi Kairatu dan diduga memiliki keterkaitan dengan kejadian gempabumi yang terjadi setelahnya. Penelitin ini menggunakan data kejadian gempabumi yang diperoleh dari katalog United State Geological Survey (USGS) dan Badan Meteorologi, Klimantologi, dan Geofisika (BMKG) pada tanggal 26 September 2019 dan setelahnya. Adapun metode yang digunakan adalah metode perubahan Coulomb stress menggunakan software Coulomb 3.3. Hasil analisis, menunjukkan bahwa gempabumi Kairatu memiliki mekanisme sumber yakni sesar geser sedikit oblige ke arah barat laut, mengalami peningkatan perubahan stress batuan positif yang dominan ke empat arah yakni utara, timur, selatan dan barat dengan kisaran harga 0,4 – 1,0 bar. Kondisi dengan nilai perubahan stress yang tinggi ini, sangat berpotensi membangkitkan gempabumi susulan dengan kedalaman hiposenter berkisar ≤ 70 km. This research aims to study the direction of the coulomb stress change caused by the Kairatu earthquake and its influence with earthquake events that occur afterwards. This research uses earthquake event data obtained from the catalog of the United State Geological Survey (USGS) and Badan Meteorologi, Klimantologi dan Geofisika (BMKG) on September 26, 2019. The method used is the Stress Coulomb Change using Coulomb 3.3 software.The results of the analysis, showed that the Kairatu earthquake had a sourceof focal mechanism is shear fault oblige to northwestward. It has increasing positive stress changes that dominant to the north, east, south and west directions with the range 0.4 - 1.0 bar. This conditions that have high stress changes are very make possible to triggering earthquake after the main earthquake occurred with the hypocenter ≤ 70 km. Kata kunci: Earthquake; Coulomb Stress Change; Kairatu.
Co-Authors Adi Susilo Bernandus Bernandus Juliany N. Mohamad Mohamad, Juliany N. Mohamad, Juliany Ningsih Sunaryo Sunaryo Valentinus G. V. Putra