Koesuma, Sorja
Department of Physics, Sebelas Maret University

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Kajian Indeks Bahaya Seismik Regional Menggunakan Data Seismik Pulau Jawa Tahun 1900-2006

INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 3, No 01 (2013): IJAP VOLUME 03 ISSUE 01 YEAR 2013
Publisher : Department of Physics, Sebelas Maret University

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It has been conducted a research about Regional Seismic Disaster Index (RSDI) in Java Island by using seismic data from 1900 – 2006. RSDI is a index showing vulnerability seismic disaster in an area. The hight risk area is the highest risk, the low area is the lowest risk. The highest RSDI areas were Banten, Jawa Barat, and D.I Yogyakarta Provinces. While the lowest RSDI areas were DKI Jakarta and Jawa Tengah Province. Deviations standard value showed the moving RSDI value each region. Region with big RSDI value had high Seismic level were Banten , Jawa Barat, and D.I. Yogyakarta Province.

Penentuan Tingkat Kerawanan Gempa Bumi Menggunakan Metode Refraksi Mikrotremor (ReMi) di Kota Surakarta

INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 7, No 1 (2017): IJAP Volume 07 ISSUE 01 YEAR 2017
Publisher : Department of Physics, Sebelas Maret University

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Berdasarkan informasi dari letak geografis dan struktur geologi, Kota Surakarta termasuk wilayah yang mengalami dampak gempa bumi[1]. Salah satu upaya untuk mengurangi dampak dari gempa bumi yaitu melakukan analisa tingkat bahaya seismik sebagai salah satu usaha mitigasi bencana gempa dengan metode mikrotremor yang dapat diketahui nilai amplifikasi dan periode dominan.  Pada penelitian telah dilakukan di Kota Surakarta menggunakan P.A.S.I Seismograph Mod. 16S24-P, 3D Borehole Geophone Model GFA 60/100. Interval pada setiap lokasi yaitu 1-3 km dengan 12 lokasi penelitian. Diperlukan waktu sekitar 20 menit dengan tiga kali pengulangan untuk perekaman data disetiap titik. Pengolahan data mikrotremor menggunakan software Geopsy dan Surfer 11. Amplifikasi rendah pada zona 1 merupakan zona yang cukup aman terhadap bahaya gempa bumi. Zona 1 berada di wilayah Mojo, Moewardi, Sangkrah, Dawung, SMPN 10, Mojosongo, Lapangan Banyuanyar, Laweyan, Karang Asem danTipes dengan amplifikasi 0,807314 sampai dengan 2,60402. Lokasi pada jenis I termasuk wilayah yang cukup aman terhadap gempa bumi karena memiliki ketebalan sedimen yang tipis daripada jenis II. Jenis I berada di wilayah Mojo, Moewardi, Sangkrah, SMPN 10, Manahan, Mojosongo, Lapangan Banyuanyar, Laweyan, Karang Asem, Jebres dan Tipes dengan  periode dominan antara 0,058978s sampai dengan 0,231411s. Sebaran tingkat kerawanan gempa bumi di kota Surakarta dapat dilihat pada peta zonasi berdasarkan nilai A0 dan T0 yang kemudian diklasifikasikan hasilnya pada zona atau jenis tertentu sehingga diperoleh informasi berupa tingkat kerawanan dan juga jenis batuan yang tersusun dibawah permukaan tanah berdasarkan parameter yang diukur.

Pemisahan Anomali Regional-Residual pada Metode Gravitasi Menggunakan Metode Moving Average, Polynomial dan Inversion

INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 3, No 01 (2013): IJAP VOLUME 03 ISSUE 01 YEAR 2013
Publisher : Department of Physics, Sebelas Maret University

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It has been done a research about separation of regional-residual anomaly in Gravity method. This research compares the result of three methods i.e. moving average method, polynomial method, and inversion method. The computer program is created using a computer programming Matlab 7. From three methods that have been made, the separation results are compared withresults of separation by using Upward Continuation method. From the results of these comparisons will be available an excellent program of regional-residual anomali separation. The results show that in polynomial method of the order 4 obtained similar contour to the separation by Upward Continuation Software. So that the output of this separation will be treated again with Grav2DC software. The output of this software is the density of rock Grav2DC of the studyarea. Processing results obtained the minimum error of 1.85% for the separation by polynomial method, while for the method of Upward Continuation obtained minimum error of 2.22%. The results obtained show that the separation of regional-residual anomali by polynomial method is similar to separation by Upward Continuation method.

Analisa Sea Level Rise Dari Data Satelit Altimetri Topex/Poseidon, Jason-1 Dan Jason-2 Di Perairan Laut Pulau Jawa Periode 2000 – 2010

INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 2, No 02 (2012): IJAP VOLUME 02 ISSUE 02 YEAR 2012
Publisher : Department of Physics, Sebelas Maret University

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It has been conducted a research about sea level rise (SLR) in surrounding Jawa island by using satellite altimetry data Topex/Poseidon, Jason-1 dan Jason-2 for period 2000 – 2010. Satellite altimetry is satellite which specially design for measuring dynamics of sea water. Those satellite lauched firstly in 1992 incorporation between National Aeronautics and Space Administration (NASA) dan European Space Agency (ESA). There are six locations for measuring SLR i.e. Jakarta, Semarang, Surabaya, Pangandaran, Jogjakarta dan Prigi. We choselocations based on alongtrack of satellite and near the big cities in Jawa island with dimension area around 0.5ox0.5o degrees. We found SLR rate for Jakarta (2.5 ± 0.24 mm/yr), Semarang (2.16 ± 0.20 mm/yr), Surabaya (2.72 ± 0.19 mm/yr), Pangandaran (0.71 ± 0.33 mm/yr), Jogjakarta (0.91 ± 0.38 mm/yr) and Prigi (1.3 ± 0.38 mm/yr). The average SLR rate for North coast is (2.46 ± 0.21 mm/yr) and for South coast (0.97 ± 0.36 mm/yr). This results are wellcorrelated with data from tide gauge stations.

Identifikasi Pola Aliran Sungai Bawah Tanah Daerah Karst di Desa Gebangharjo Kecamatan Pracimantoro Menggunakan Metode Tomography Resistivity Konfigurasi Wenner-Schlumberger

INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 7, No 2 (2017): IJAP Volume 07 ISSUE 02 YEAR 2017
Publisher : Department of Physics, Sebelas Maret University

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This research is conducted using 4 lines data with 750 meters in length. Tomography resistivity with Wenner-Schlumberger configuration is used as this research methodology to take the data with a = 50 meters and n=1, 2, 3, 4, 5, 6. Resistivitymeter OYO 2119C McOHM-ELmodel is used as the instrument. Furthermore, the data is processed with two softwares; Res2Dinv ver. 3.56.22 to get 2D resistivity section and RockWork16to make 3D model of the site. The underground river’s chamber is made by hollow carbonate rocks with the resistivity of >412 Ωmand 117,6 Ωm – 412 Ωm for limestone’s resistivity as its capsrock. Researching to the depth of 173 meters, underground rivers are shown in the line 2 in the depth of 65 to 134 meters, 65 to 173 meters in the line 3, and in the cross section of line 3 and line 4. While in the first trajectory, another chamber is found within the depth of 12.5 to 40 meters. It is expected that the underground river is flowing to the south because of the chamber in third and fourth trajectory are lower than second trajectory.

Analisa Cekungan Air Tanah Dalam di Bagian Barat Kabupaten Grobogan, Jawa Tengah

INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 8, No 1 (2018) : IJAP Volume 8 ISSUE 01 YEAR 2018
Publisher : Department of Physics, Sebelas Maret University

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Penelitian ini menganalisa kedalaman air tanah dalam dengan mengunakan survai geolistrik yang terletak di sisi barat Kabupaten Grobogan, Jawa Tengah, Indonesia. Terdapat empat lokasi survai yaitu Desa Brabo dan Desa Padang (Kecamatan Tanggungharjo), Desa Deras dan Desa Padas (Kecamatan Kedungjati). Konfigurasi Schlumberger digunakan dalam survai geolistrik ini dengan bentangan elektroda arus sampai dengan 600 meter. Diperoleh kedalaman potensi air tanah dalam pada kedalaman antara 50 – 105 meter. Hasil ini sesuai dengan peta cekungan air tanah Kabupaten Grobongan.

Penentuan Tingkat Kekerasan Batuan Menggunakan Metode Seismik Refraksi di Jatikuwung Karanganyar

INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 3, No 01 (2013): IJAP VOLUME 03 ISSUE 01 YEAR 2013
Publisher : Department of Physics, Sebelas Maret University

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It has been done a research about the determination of rock hardness level by using refraction seismic method in Jatikuwung Karanganyar. The research is done by using Seismograph PASI 16S24-P with the path length of 48 meters, distance between geophone 2 meters, 5 shots in each spread and there are four surveys part totally. The processing data is done by using SeisImager software with Plotrefa and Pickwin95 program.We use intercept time method for data processing. The determination of rock hardness use Gardner’s relationship formula. Based on interpretation, there are three layers lithology structure with P wave propagation velocity of 200-1800 m/s and its density of 1.17–1.93 gr/cc. Based on velocity analysis we determine the velocity of first layer is 200-700 m/s, second layer 700-1500 m/s, and third layer 1500-1800 m/s. The subsurface hardness lithology consists of top soil, sands and unsaturated pebble (1.17–1.59 gr/cc) with the depth 2–4 meters in the first layer, saturatedsands, saturated pebble, and alluvium (1.59–1.93 gr/cc) with the depth 9.5–11.5 meters in the second layer, and clay and sands (1.93–2.02 gr/cc) with the depth of 5.5–6 meters in the third layer. The rock hardness is located at the depth betwen 12 – 20 meters.

Identifikasi Bidang Gelincir di Dusun Dukuh, Desa Koripan, Kecamatan Matesih, Kabupaten Karanganyar, Menggunakan Metode Geolistrik Resistivitas Konfigurasi Wenner Alfa

INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 6, No 02 (2016): IJAP Volume 06 Issue 02 Year 2016
Publisher : Department of Physics, Sebelas Maret University

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Slip surface identification in Dukuh, Koripan Village, Matesih Sub-district, Karanganyar District has been conducted with geoelectrical resistivity method with Wenner Alfa configuration. Data acquisitions was done on 5 sample lines. The length of each line is 75 meter. The smallest electrode spacing’s 3 meter, with multiplier (n) between 1 to 5. Two dimensional results show that slip surface in every sample lines formed by watertight wet clays material, with resistivity 8,99 Ωm until 13,4 Ωm. The depth of the slip surface in each line is varies. Slip surface of the line 1 was found at a depth of 1 meter to 3,7 meter, the line 2 was found at 2 meter to 4 meter, the line 3 was found at 0,75 meter to 3,78 meter, the line 4 was found at 1,5 meter to 3,5 meter, and the slip surface of line 5 was found at 0,75 meter to 3 meter. Three dimenisonal result show that the area with high land movement was covered by sandy-clay materials.