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ANALISIS SEISMOGRAM TIGA KOMPONEN TERHADAP MOMENT TENSOR GEMPA BUMI DI MANOKWARI PAPUA 03 JANUARI 2009 Bagus Jaya Santosa, Irwan Setyowidodo,
Jurnal Neutrino JURNAL NEUTRINO (Vol 3 No 2
Publisher : Department of Physics, Maulana Malik Ibrahim State Islamic University of Malang

Penelitian ini melakukan analisis inversi waveform 3 komponen terhadap data gempa bumi yangÂ terjadiÂ diÂ ManokwariÂ PapuaÂ padaÂ tanggalÂ 3Â JanuariÂ 2009Â pukulÂ 19:43:55Â GMTÂ dengan magnitudeÂ 7.1Â MwÂ yangÂ episentrumnyaÂ beradaÂ padaÂ lattitudeÂ -0.70541,Â longitudeÂ 125.8455Â dan kedalaman 25 km. Data yang digunakan dalam penelitian ialah, data seismik lokal yang diunduh dari dataÂ gempaÂ IA.Â SelanjutnyaÂ dilakukanÂ prosesÂ Â inversiÂ dataÂ waveformÂ tigaÂ komponenÂ dengan menggunakanÂ metodeÂ iterasiÂ dekonvolusi.Â MetodeÂ iniÂ diimplementasikanÂ dalamÂ softwareÂ ISOLA yangÂ dikembangkanÂ Â untukÂ mendapatkanÂ parameter-parameterÂ sumberÂ gempaÂ bumi.Â Parameter- parameterÂ gempa ini tergambarkan dalam Centroid Moment Tensor dan parameter sesar penyebab gempa. Selanjutnya, hasil parameter-patameterÂ tersebut digunakan untukÂ mengetahui arahÂ patahan yang sebenarnya (fault-plane) dengan menggunakan metode H-C. Seismogram sintetik dihitung dengan ISOLA yang inputnya adalah model bumi dan data seismogram yangÂ direkamÂ olehÂ stasiunÂ seismologiÂ BAK,Â LBMÂ danÂ JAY.Â HasilÂ Â interpretasiÂ atasÂ analisis seismogramÂ Â waveformÂ Â tigaÂ Â komponenÂ Â menunjukkanÂ Â bahwaÂ Â orientasiÂ Â bidangÂ Â patahanÂ Â gempa Manokwari Papua pada tanggal 3 Januari 2009 memiliki sudut dip 54oÂ Â Â Â Â Â terhadap bidangÂ horizontal yang menyebabkan zona patahan di daerah tersebut mudah bergeser dan mudah terjadi gempa. Hasil analisisÂ iniÂ diketahuiÂ bahwaÂ sesarÂ penyebabÂ gempaÂ bumiÂ iniÂ ialahÂ sesarÂ strike-slipÂ obliqueÂ yang bergerak dariÂ arah baratÂ laut - tenggara. SumberÂ gempaÂ bumiÂ yang terjadi tersebut terjadi akibat aktivitas Sesar Sorong yang terdapat di bagian utara Manokwari.

PENERAPAN METODE VERY LOW FREQUENCY ELECTROMAGNET (VLF-EM) UNTUK MENAFSIRKAN BIDANG LONGSORAN, STUDI KASUS DESA JOMBOK, KECAMATAN NGANTANG, KABUPATEN MALANG, JAWA TIMUR Wijayanto, Totok; Santosa, Bagus Jaya; Warnana, Dwa Desa; Candra, Arya Dwi
Jurnal Spektra Vol 16, No 3 (2015): Spektra: Jurnal Fisika dan Aplikasinya
Publisher : Jurnal Spektra

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AbstrakKelongsoran sering terjadi pada tanah yang memiliki topografi curam. Salah satunya adalah yang terjadi di Desa Jombok, Kecamatan Ngantang, Kabupaten Malang, Jawa Timur. Pada areal seluas satu hektar dijumpai penurunan permukaan tanah (longsor). Daerah longsoran ini diteliti dengan menggunakan salah satu metoda Geofisika, yaitu Very Low Frequency-Electromagnetic (VLF-EM). Data lapangan yang didapatkan dari hasil pengukuran metode VLF-EM biasanya tercampur dengan noise dan outlier. Pada penelitian ini digunakan filter NA-MEMD untuk menghilangkan noise dan outlier. Digunakan Filter Karous-Hjelt untuk menganalisa data secara kualitatif. Sedangkan analisa secara kuantitatif diperoleh dengan melakukan pemodelan inversi menggunakan INV2DVLF. Hasil analisis VLF-EM dengan menggunakan filter NA-MEMD mampu mereduksi noise dan outlier dari data pengukuran. Sedangkan hasil inversi 2D menunjukkan bahwa terdapat zona anomali yang menunjukkan zona lemah atau rawan longsor di area penelitian.Â AbstractLandslide often occurs in a steep topography ground. One of them is happened in the Jombok village, Ngantang, Malang, East Java. Land subsidence (landslides) often occur in this area. The landslide area investigated using one of the Geophysics methods, the Very Low Frequency-Electromagnetic (VLF-EM). The field datas obtained from measurement results of VLF-EM method are usually mixed with noise and outliers. In this research, NA-MEMD filter.is used to eliminate the noise and outliers. Karous-Hjelt (K-Hjelt) filter is udes to qualitative analyze of the data. While quantitative analysis is obtained by performing inversion modeling using INV2DVLF. VLF-EM analysis results using the NA-MEMD filter is able to reduce the noise and outliers of measurement data. While the 2D inversion results indicate that there is an anomalous zone which indicates weak or landslide-prone zones in the study area.Keywords: VLF-EM, NA-MEMD, K-Hjelt filter, INV2DVLF, Landslide.

Seismic Anisotropy Analysis Beneath Sumatra Revealed by Shear-Wave Splitting Candra, Arya Dwi; Santosa, Bagus Jaya; Rachman, Gazali
Indonesian Journal on Geoscience Vol 4, No 3 (2017)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.4.3.169-179

DOI: 10.17014/ijog.4.3.169-179A shear-wave splitting analysis was determined to observe anisotropic structures of an upper mantle layer beneath Sumatra. The data were collected from 35 BMKG stations with the magnitude of more than 6.25 Mw and the epicentre of 85o - 140o. A shear-wave splitting measurement was calculated by using Splitlab based on three methods simultaneously. The result of the shear-wave splitting measurement in the Sumatra Forearc and Fault Zone shows that there are two anisotropic layers. The first layer has a dominant-fast-polarization direction that is parallel with a trench, and has the delay time duration of 0.5 - 0.9 s-. It is presumed that it is caused by a shear-strain as a result of the existences of Mentawai and Sumatra Fault Zones. The second layer has a dominant-fast-polarization direction that is perpendicular to the trench with the delay time duration of about 1.1 - 1.9 s-. It is presumed that it is caused by a movement of a subduction plate on a mantle wedge. The measurement in the backarc shows that there is only one anisotropic layer that is a subduction plate. It is also found that there is a transition of an orientation change on the subduction plate between Sumatra and Java. The change of the polarization direction is probably related to the age difference and the direction velocity of the absolute plate movement (APM) from Sumatra to Java.

HYPOCENTER DISTRIBUTION OF LOW FREQUENCY EVENT AT PAPANDAYAN VOLCANO Hasan, Muhammad Mifta; Triastuty, Hetty; Santosa, Bagus Jaya; Widodo, Amien
Jurnal Neutrino Vol 9, No 1 (2016): October
Publisher : Department of Physics, Maulana Malik Ibrahim State Islamic University of Malang

Papandayan volcano is a stratovolcano with irregular cone-shaped has eight craters around the peak. The most active crater in Papandayan is a Mas crater. Distribution of relocated event calculated using Geiger Adaptive Damping Algorithm (GAD) shows that the epicenter of the event centered below Mas crater with maximum rms 0.114. While depth of the hypocenter range between 0-2 km and 5-6 km due to activity of steam and gas.

Estimasi Parameter Sumber Gempa Bumi Padang 30 September 2009, Mw=7,6 dan Korelasinya dengan Aftershocks-Nya Madlazim, Madlazim; Santosa, Bagus Jaya
Jurnal Matematika dan Sains Vol 19 No 3 (2014)
Publisher : Institut Teknologi Bandung

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Penelitian ini bertujuan untuk mengestimasi parameter-parameter sumber gempa bumi dan perubahan tekanan Coulomb akibat dari gempa bumi Padang 30 September 2009. Data gelombang seismik 3 komponen telah direkam oleh 4 stasiun, yaitu BTDF yang berjarak 489,6 km, stasiun KOM yang berjarak 521,9 km, stasiun IPM yang jarak dan arah 596,5 km, dan stasiun KUM yang berjarak 677 km dari episentrum. Metode yang digunakan untuk mengananlisis gelombang seismik tersebut adalah metode Diskritisasi Bilangan Gelombang secara iteratif. Metode ini diimplementasikan dalam software ISOLA, untuk mendapatkan parameter-parameter sumber gempa bumi. Parameter-parameter sumber gempa bumi ini selanjutnya digunakan untuk menentukan orientasi bidang patahan dan menghitung perubahan tekanan Coulomb Untuk menentukan orientasi bidang patahan yang sesungguhnya digunakan metode HC-plot. Hasil analisis menunujukkan bahwa orientasi bidang patahan gempa tersebut melintang di pulau Sumatera dan memiliki sudut dip 53° terhadap bidang horisontal dan memiliki strike 73° terhadap Utara. Kenaikan tekanan Coulomb di suatu daerah akan memicu zona patahan yang ada di daerah tersebut untuk bergeser. Jika patahan tersebut bergeser, maka akan melepaskan energi secara mendadak dan jika energi ini sampai di permukaan bumi, maka akan terjadi gempa bumi tektonik susulan. Berdasarkan plot tekanan Coulomb terlihat bahwa gempa Jambi tanggal 1 Oktober 2009 dipicu oleh tekanan Coulomb gempa Padang 30 September 2009. Kata kunci: Parameter sumber gempa bumi, Orientasi bidang sesar dan tekanan Coulomb. Earthquake Source Parameters Estimation at Padang September 30, 2009 and Its Correlation With Aftershocks Abstract This study aims to estimate the source parameters of earthquakes and Coulomb stress changes resulting from Padang earthquake of 30 September 2009 by using 3-component seismic waveform data recorded by BTDF station within 489.6 miles, COM stations within 521.9 miles, IPM station within 596.5 miles, and KUM stations within 677 km of the epicenter. The method that was used to analyze the seismic wave is Discretization Iteratively Wave Numbers method. This method is implemented in software ISOLA, to obtain the parameters of the earthquake source. The parameters of the earthquake source is then used to determine fracture orientation and calculate the area of Coulomb stress changes in order to determine the orientation of the field of real faults used HC-plot method. The results show that the orientation of the earthquake fault areas across the island of Sumatera and has a dip angle of 53° to the horizontal plane and has a strike of 73 ° against the North. Coulomb pressure rise in an area will trigger a fault zone in the area to shift. If the fault is shifted, then suddenly releases energy and this energy to the surface of the earth, there will be aftershocks. Based on Coulomb stress plot looks that earthquake Jambi October 1, 2009 triggered by Coulomb stress Padang earthquake September 30, 2009. Keywords: Earthquake source parameters, Orientation of fault plane and Coulomb stress changes.

S Wave Velocity Structure in Non-tectonic Indo-China by Analyzing the Earthquakes in Sumatra-Java in TATO Station, Taiwan Santosa, Bagus Jaya
JURNAL TEKNOLOGI TECHNOSCIENTIA Technoscentia Vol 1 No 2 Februari 2009
Publisher : Lembaga Penelitian & Pengabdian Kepada Masyarakat (LPPM), IST AKPRIND Yogyakarta

The velocity structure of S wave under South-East Asia and South China Ocean due to earthquakes in Sumatra-Java subduction zone which data is recorded in TATO, Taiwan seismological station, has been investigated through seismogram analysis in time domain and three components simultaneously. The synthetic seismogram was calculated using GEMINI method, with the inputs are the earth model and the CMT solution of the earthquakes. A low-pas filter with corner frequency of 20 mHz was applied on the seismograms. Applying the deconvolution of unit response on the synthetic seismogram the seismogram comparison was executed in the same unit. The seismogram comparison indicated that the calculation from PREMAN synthetic seismogram deviates significantly from the measured ones. The deviation occurred on the arrival time of surface wave of Rayleigh and Love as well as S body waves. The interpretation results of seismogram analysis using waveform indicate that non-tectonic South-East Asia area in front of subduction zone has strong negative correction of ï¢v in the upper mantle and with smaller factor also at earth layers below. This result shows stronger vertical anisotropy than one in PREMAN earth model.

STRUKTUR KECEPATAN GELOMBANG S DI DAERAH DEPAN BIDANG SUBDUKSI ALASKA DENGAN MENGANALISA SEISMOGRAM GEMPA C022801L DI STASIUN WHY Santosa, Bagus Jaya
JURNAL TEKNOLOGI TECHNOSCIENTIA Academia Ista Vol 12 No 02 Februari 2008
Publisher : Lembaga Penelitian & Pengabdian Kepada Masyarakat (LPPM), IST AKPRIND Yogyakarta

In this research the measured seismogram of C022801L, Washington U.S.A. is compared to the synthetic seismogram, which is recorded at WHY observation station in three dimensions, where the wave path resides in front area of Alaska subduction zone. The synthetic seismogram is calculated with the GEMINI Program, whose input is in the form of an earth model, which is radial symmetry and transversal isotropic, and the CMT solution of the quake.Simulation and seismogram comparison can only be conducted till a frequency to 15 mHz, because big discrepancies are found at surface wave and the depth wave phase ScS. The surface wave propagates along earth surface till a depth which is equivalent to depth of upper mantle; so that the fitting can be obtained by altering speed structure till base of upper mantle, where the corrections are conducted at bh speed gradient. Correction at upper mantle structure does not bring repair at wave phase ScS. Corrective is further executed at speed structure of shear wave S till CMB, until the good fitting at ScS wave is obtained. S velocity structure in front area of Alaska subduction zone has in reality a strong positive anomaly, and to get fitting at ScS wave, the positive anomaly continues at earth layers below upper mantle till CMB

3D Seismic Tomography Imaging of Taiwan Substructure Diah Ningrum, Susi Anggraini; Santosa, Bagus Jaya
IPTEK Journal of Proceedings Series No 1 (2015): 1st International Seminar on Science and Technology (ISST) 2015
Publisher : Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j23546026.y2015i1.1041

Taiwan has a high rate of crustal deformation and a strong seismic activity. Taiwan is located on the convergent boundary between the Eurasian and the Philippine Sea plates. Seismic tomography is an imaging technique that uses seismic waves to create three-dimensional images of Earthâ€™s interior. We use the earthquake of M > 4.7 and occurred in the period of 1 January 2009 to 31 December 2010. The data processing steps of seismic tomography are picking of P and S wave using SeisGram2K60, hypocenter relocation using Hypo71, and tomography inversion using LOTOS-12. The result shows that there is high Vp and Vs in the eastern Taiwan that represent the western boundary of Philippine Sea Plate with Longitudinal Valley.

S Wave Velocity Structure in Non-tectonic Indo-China by Analyzing the Earthquakes in Sumatra-Java in TATO Station, Taiwan Santosa, Bagus Jaya
JURNAL TEKNOLOGI TECHNOSCIENTIA Technoscentia Vol 1 No 2 Februari 2009
Publisher : Lembaga Penelitian & Pengabdian Kepada Masyarakat (LPPM), IST AKPRIND Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.34151/technoscientia.v1i2.392

The velocity structure of S wave under South-East Asia and South China Ocean due to earthquakes in Sumatra-Java subduction zone which data is recorded in TATO, Taiwan seismological station, has been investigated through seismogram analysis in time domain and three components simultaneously. The synthetic seismogram was calculated using GEMINI method, with the inputs are the earth model and the CMT solution of the earthquakes. A low-pas filter with corner frequency of 20 mHz was applied on the seismograms. Applying the deconvolution of unit response on the synthetic seismogram the seismogram comparison was executed in the same unit. The seismogram comparison indicated that the calculation from PREMAN synthetic seismogram deviates significantly from the measured ones. The deviation occurred on the arrival time of surface wave of Rayleigh and Love as well as S body waves. The interpretation results of seismogram analysis using waveform indicate that non-tectonic South-East Asia area in front of subduction zone has strong negative correction of ï¢v in the upper mantle and with smaller factor also at earth layers below. This result shows stronger vertical anisotropy than one in PREMAN earth model.

STRUKTUR KECEPATAN GELOMBANG S DI DAERAH DEPAN BIDANG SUBDUKSI ALASKA DENGAN MENGANALISA SEISMOGRAM GEMPA C022801L DI STASIUN WHY Santosa, Bagus Jaya
JURNAL TEKNOLOGI TECHNOSCIENTIA Academia Ista Vol 12 No 02 Februari 2008
Publisher : Lembaga Penelitian & Pengabdian Kepada Masyarakat (LPPM), IST AKPRIND Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.34151/technoscientia.v0i0.2001

In this research the measured seismogram of C022801L, Washington U.S.A. is compared to the synthetic seismogram, which is recorded at WHY observation station in three dimensions, where the wave path resides in front area of Alaska subduction zone. The synthetic seismogram is calculated with the GEMINI Program, whose input is in the form of an earth model, which is radial symmetry and transversal isotropic, and the CMT solution of the quake.Simulation and seismogram comparison can only be conducted till a frequency to 15 mHz, because big discrepancies are found at surface wave and the depth wave phase ScS. The surface wave propagates along earth surface till a depth which is equivalent to depth of upper mantle; so that the fitting can be obtained by altering speed structure till base of upper mantle, where the corrections are conducted at bh speed gradient. Correction at upper mantle structure does not bring repair at wave phase ScS. Corrective is further executed at speed structure of shear wave S till CMB, until the good fitting at ScS wave is obtained. S velocity structure in front area of Alaska subduction zone has in reality a strong positive anomaly, and to get fitting at ScS wave, the positive anomaly continues at earth layers below upper mantle till CMB

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