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All Journal Jurnal Matematika & Sains Journal of Mathematical and Fundamental Sciences Journal of Engineering and Technological Sciences JURNAL METEOROLOGI DAN GEOFISIKA Jurnal Geofisika Journal of Engineering and Technological Sciences
Sri Widiyantoro
Global Geophysics Research Division, Faculty Of Mining And Petroleum Engineering, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung, Jawa Barat 40132, Indonesia
Aerospace Engineering Astronomy Automotive Engineering Chemical Engineering, Chemistry & Bioengineering Chemistry Civil Engineering, Building, Construction & Architecture Earth & Planetary Sciences Electrical & Electronics Engineering Energy Engineering Mathematics Physics

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Journal : Journal of Engineering and Technological Sciences

 1 
Complex Morphology of Subducted Lithosphere in the Mantle below the Molucca Collision Zone from Non-linear Seismic Tomography Widiyantoro, Sri
Journal of Engineering and Technological Sciences Vol 35, No 1 (2003)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (771.494 KB) | DOI: 10.5614/itbj.eng.sci.2003.35.1.1

Abstract

Results of seismic studies presented in previous publications depict two opposing subducted oceanic lithospheric slabs under the Molucca region. This unique structure is related to the arc-arc collision between the Halmahera and Sangihe arcs. Recently, we have revisited the complex subduction zone structure by employing a non-linear tomographic imaging technique in which 3-D ray tracing has been implemented. We have used P- as well as S-wave arrival times from carefully reprocessed global data set. The results provide some improvements in the positioning of wave-speed anomalies. Consistent with earlier results, the new P-wave model depicts the two opposing subducted slabs of the Molucca Sea plate. The intriguing new observation is that the westward dipping slab appears to penetrate into the lower mantle by taking the form of folded slab. We envisage that the folding behavior may have been caused by the shift of the whole subduction system in the Molucca region toward the Eurasian continent due to the westward thrust of the Pacific plate combined with the large left-lateral movement of the Sorong fault. The inversion of traveltime residuals of direct S phases strongly confirms the new observation.
Estimation of Slip Distribution of the 2007 Bengkulu Earthquake from GPS Observations Using the LeastSquares Inversion Method Awaluddin, Moehammad; Meilano, Irwan; Widiyantoro, Sri
Journal of Engineering and Technological Sciences Vol 44, No 2 (2012)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (579.484 KB) | DOI: 10.5614/itbj.eng.sci.2012.44.2.6

Abstract

Continuous  Global  Positioning  System  (GPS)  observations  showed significant  crustal  displacements  as  a  result  of  the  Bengkulu  earthquake occurring on September 12, 2007. A maximum horizontal displacement of 2.11 m was observed at PRKB station, while the vertical component at BSAT station was lifted up with a maximum of 0.73 m, and the vertical component at LAIS station had subsided  –0.97 m. Adding more constraints on the inversion for the Bengkulu earthquake slip distribution inferred from GPS observations can help solve  the  underdetermined  least-squares  inversion.  Checkerboard  tests  were performed  to  help  conduct  the  weighting  for  constraining  the  inversion.  The inversion calculation yielded an optimal value for the slip distribution by giving the smoothing constraint a weight of 0.001 and the slip constraint a weight of = 0 at the edge of the earthquake rupture area. The maximum co-seismic slip of the optimal inversion calculation was 5.12 m at the lower area of PRKB station and BSAT station. The seismic moment calculated from the optimal slip distribution was 7.14 x 1021 Nm, which is equivalent to a magnitude of 8.5.
Borehole Microseismic Imaging of Hydraulic Fracturing: A Pilot Study on a Coal Bed Methane Reservoir in Indonesia Ry, Rexha Verdhora; Septyana, Tepy; Widiyantoro, Sri; Nugraha, Andri Dian; Ardjuna, Arii
Journal of Engineering and Technological Sciences Vol 51, No 2 (2019)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (26.343 KB) | DOI: 10.5614/j.eng.technol.sci.2019.51.2.7

Abstract

Over the last decade, microseismic monitoring has emerged as a considerable and capable technology for imaging stimulated hydraulic fractures in the development of unconventional hydrocarbon resources. In this study, pilot hydraulic-fracturing treatments were operated at a coal-bed methane (CBM) field in Indonesia to stimulate the flow and increase the reservoir’s permeability while the monitoring system was set in a single near-vertical borehole. Locating event sources accurately is fundamental to investigating the induced fractures, but the geometry of a single downhole array is a challenging data processing task, especially to remove ambiguity of the source locations. The locating procedure was reviewed in 3 main steps: (i) accurate picking of P- and S-wave phases; (ii) inclusion of P-wave particle motion to estimate the back azimuth; (iii) guided inversion for hypocenter determination. Furthermore, the seismic-source moment magnitudes were calculated by employing Brune’s model. Reliable solutions of locations were obtained as shown statistically by uncertainty ellipsoids and a small misfit. Based on our results, both induced and triggered seismicity could be observed during the treatments and therefore conducting intensive monitoring is important. The triggered seismicity is an undesired activity so disaster precautions need to be taken, in particular for preventing reactivation of pre-existing faults.
Estimation of Slip Distribution of the 2007 Bengkulu Earthquake from GPS Observations Using the LeastSquares Inversion Method Moehammad Awaluddin; Irwan Meilano; Sri Widiyantoro
Journal of Engineering and Technological Sciences Vol. 44 No. 2 (2012)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.eng.sci.2012.44.2.6

Abstract

Continuous  Global  Positioning  System  (GPS)  observations  showed significant  crustal  displacements  as  a  result  of  the  Bengkulu  earthquake occurring on September 12, 2007. A maximum horizontal displacement of 2.11 m was observed at PRKB station, while the vertical component at BSAT station was lifted up with a maximum of 0.73 m, and the vertical component at LAIS station had subsided  "“0.97 m. Adding more constraints on the inversion for the Bengkulu earthquake slip distribution inferred from GPS observations can help solve  the  underdetermined  least-squares  inversion.  Checkerboard  tests  were performed  to  help  conduct  the  weighting  for  constraining  the  inversion.  The inversion calculation yielded an optimal value for the slip distribution by giving the smoothing constraint a weight of 0.001 and the slip constraint a weight of = 0 at the edge of the earthquake rupture area. The maximum co-seismic slip of the optimal inversion calculation was 5.12 m at the lower area of PRKB station and BSAT station. The seismic moment calculated from the optimal slip distribution was 7.14 x 1021 Nm, which is equivalent to a magnitude of 8.5.
Complex Morphology of Subducted Lithosphere in the Mantle below the Molucca Collision Zone from Non-linear Seismic Tomography Sri Widiyantoro
Journal of Engineering and Technological Sciences Vol. 35 No. 1 (2003)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.eng.sci.2003.35.1.1

Abstract

Results of seismic studies presented in previous publications depict two opposing subducted oceanic lithospheric slabs under the Molucca region. This unique structure is related to the arc-arc collision between the Halmahera and Sangihe arcs. Recently, we have revisited the complex subduction zone structure by employing a non-linear tomographic imaging technique in which 3-D ray tracing has been implemented. We have used P- as well as S-wave arrival times from carefully reprocessed global data set. The results provide some improvements in the positioning of wave-speed anomalies. Consistent with earlier results, the new P-wave model depicts the two opposing subducted slabs of the Molucca Sea plate. The intriguing new observation is that the westward dipping slab appears to penetrate into the lower mantle by taking the form of folded slab. We envisage that the folding behavior may have been caused by the shift of the whole subduction system in the Molucca region toward the Eurasian continent due to the westward thrust of the Pacific plate combined with the large left-lateral movement of the Sorong fault. The inversion of traveltime residuals of direct S phases strongly confirms the new observation.
Borehole Microseismic Imaging of Hydraulic Fracturing: A Pilot Study on a Coal Bed Methane Reservoir in Indonesia Rexha Verdhora Ry; Tepy Septyana; Sri Widiyantoro; Andri Dian Nugraha; Arii Ardjuna
Journal of Engineering and Technological Sciences Vol. 51 No. 2 (2019)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2019.51.2.7

Abstract

Over the last decade, microseismic monitoring has emerged as a considerable and capable technology for imaging stimulated hydraulic fractures in the development of unconventional hydrocarbon resources. In this study, pilot hydraulic-fracturing treatments were operated at a coal-bed methane (CBM) field in Indonesia to stimulate the flow and increase the reservoir's permeability while the monitoring system was set in a single near-vertical borehole. Locating event sources accurately is fundamental to investigating the induced fractures, but the geometry of a single downhole array is a challenging data processing task, especially to remove ambiguity of the source locations. The locating procedure was reviewed in 3 main steps: (i) accurate picking of P- and S-wave phases; (ii) inclusion of P-wave particle motion to estimate the back azimuth; (iii) guided inversion for hypocenter determination. Furthermore, the seismic-source moment magnitudes were calculated by employing Brune's model. Reliable solutions of locations were obtained as shown statistically by uncertainty ellipsoids and a small misfit. Based on our results, both induced and triggered seismicity could be observed during the treatments and therefore conducting intensive monitoring is important. The triggered seismicity is an undesired activity so disaster precautions need to be taken, in particular for preventing reactivation of pre-existing faults.
Co-Authors A. Afnimar A. Ardianto A. D. Nugraha A. Riyanto Adhatus Solichah Ahmadiyah, Adhatus Solichah Andri Dian Nugraha Ardjuna, Arii Arii Ardjuna Auly, Muhammad Fariq Riesky Awali Priyono Awan Gunawan B. S. Prabowo Bambang Sunardi Bayu Pranata, Bayu Daryono, Mudrik Rahmawan David P. Sahara Dicky Ahmad Zaky Dwa Desa Warnana Edy Santoso Edy Soewono Fadhilah, Fildzah Zaniati Gede Suantika Gede Suantika Gede Suantika Gunawan Ibrahim Gunawan Ibrahim Gunawan, Mohamad Taufik Guntur Pasau H. Afif Habibah, Nur Fani Hendro Nugroho Hiroaki Yamanaka I Nyoman Sukanta irwan meilano Jimmi Nugraha M. Muzli Masturyono Masturyono Masyhur Irsyam Moehammad Awaluddin Mohamad Ridwan Mohamad Ridwan Nanang T. Puspito Nanang T. Puspito Octantyo, Ardian Yudhi Oktavia, Nur Hidayati Palgunadi, Kadek Hendrawan Pepen Supendi Permana, Dadang Persada, Yoga Dharma Pupung Susilanto Rahman, Aditya Setyo Rahmatullah, Fajri Syukur Ramdhan, Mohammad  Rexha Verdhora Ry Ry, Rexha Verdhora Ry, Rexha Verdhora Saputra, Ryandika Sativa, Oriza Septyana, Tepy Shengji Wei Simanjuntak, Andrean Vesalius Hasiholan Sirait, Anne Meylani Magdalena Sorja Koesuma Suhardja, Sandy Kurniawan Sujabar, Sujabar Sulastri Sulastri Supendi, Pepen Supriyanto Rohadi Suryanto, Wiwit Syaifuddin, Firman Tepy Septyana Thomas Hardy Triahandini, Agnis Triyono, Rahmat Wallansha, Robby Wandono Wandono Wiko Setyonegoro Y.M. Husni Yoichi Fukuda Z. Zulfakriza Zulfakriza, Zulfakriza