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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.

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

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.

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.

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

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.

Relocation Of Earthquake Hypocenter In The Flores Region Using Hypo71 Regolinda Maneno; Bagus Jaya Sentosa; Gazali Rachman
IPTEK The Journal of Engineering Vol 5, No 2 (2019)
Publisher : Lembaga Penelitian dan Pengabdian kepada Masyarakat

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j23378557.v5i2.a5024

Flores is one of the seismically high activity zones of Indonesia region as a consequence of Indo-Australian plate subduction under the Eurasian plate. Tectonic earthquakes required to be studied because in large magnitude it can bring disaster. Therefore the precise of hypocenter determination needs to be done. In this study, hypocenter relocation is done by Single Event Determination method using hypo71. The data used are earthquake event data in Flores area which has magnitude > 4 SR at period between January 2010 and March 2018 obtained from BMKG catalog. Hypo71 requires data of arrival time of P and S waves at the recorder station. The arrival time of P and S waves data at each station is obtained by picking P and S waves using SeisGram2k70. The results showed that the source of the earthquake experienced a change of position both horizontally and vertically. In the vertical direction of hypocenter earthquake changes in the distance between 0.02 - 89.61 km, while in the horizontal direction the hypocenter of the earthquake changes in the distance of 1.11 - 71.11 km. After relocation, the hypocenter of the earthquake distributed along the Back Arc Trust in the northern island of Flores. Hypocenter relocation using hypo71 yields a small residual between the observation time and calculation time denoted by RMS <1.

Coulomb Stress Change Analysis Center of Celebes on 29th May 2017 6.6 Mw Earthquake and Aftershocks Distribution Ibrahim Ibrahim; Gazali Rachman; Bagus Jaya Santosa
IPTEK Journal of Proceedings Series No 1 (2019): 4th International Seminar on Science and Technology 2018 (ISST 2018)
Publisher : Institut Teknologi Sepuluh Nopember

Mechanism of earthquakes associated with the distribution of stress static that occurs in rocks. When the rocks elastic limit is exceeded there will be a release of energy as an earthquake result as rocks no longer able to withstand the stress that will disturb the stress field in the neighborhood. In this study, analysis stress of changes was done by taken earthquake data Center of Celebes 6.6 Mw on May 29th, 2017 with hypocenter 13 km using four earthquake recording stations namely BKB, TOLI, PMSI, and LUWI through website GFZ (Geo Forschungs Zentrum) and Global CMT (Global Centroid Moment Tensor), and then calculated the earthquake source parameters so as to obtain model focal mechanism using discretization methods are iterative wave numbers and analyzed using Coulomb 3.3 to obtain the value of Coulomb stress change and its aftershocks distribution. Analysis results showed that orientation the focal mechanism model of earthquake fault plane has been a normal fault type, fault length 27.54 km, width fault 14.06 km with slip shift of 79.06 cm. Coulomb stress Changes are generated ranging from 0.05 to 0.2 bar trending southwest-northwest and northeast-southeast of the epicenter, Based on Coulomb stress plot that center of Celebes 6.6 Mw on May 29, 2017 earthquake triggering aftershocks on May 29th, 2017 at 14:53:44 UTC with latitude and longitude -1.12 ° and 120.17 ° northwest trending with a range of values from 0.1 to 0.05 bar, on May 31, 2017 at 04:42:06 with latitude and longitude -1.17 ° and 120.79 ° north-east trending with a range of values from 0.15 to 0.1 bar and on November 25, 2017 at 09:14:51 UTC with latitude and longitude -1.18 ° and 119.93 ° and 11:11:24 UTC with latitude and longitude -1.19 ° and 119.94 westbound with a range of values from 0.05 to 0.01 bar

Hypocenter Relocation of Volcanic Earthquake at Agung Vulcano Reni Agustiani; Bagus J. Santosa; Yasa Suparman; Devi K. Syahbana; Gazali Rachman
IPTEK Journal of Proceedings Series No 1 (2019): 4th International Seminar on Science and Technology 2018 (ISST 2018)
Publisher : Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j23546026.y2019i1.5119

Agung Volcano is a stratovolcano located in the area of Karangasem regency of Bali and is in the northwest-southeast fault alignment with Batur, Abang and Seroja Volcano. The existence of this alignment allegedly related to the fracture in the northwest of the island of Bali. The eruption of Agung Volcano recorded on November 25th, 2017 was a significant danger for people living around it. Therefore, it is necessary to monitor the activity of Agung Volcano. The method used in this study is the relocation of volcanic earthquake sources to determine the location of the source of the earthquake which caused an increase in Mount activity. Hypocenter relocation was carried out on 138 earthquake events during October 2017-January 2018 using the Coupled Velocity-Hypocenter method. Hypocenter was obtained at a depth of less than 10 km under sea level with an RMS value <0.3 seconds, and this is thought to have a flow of magma fluid through the conduit which moves towards the earth's surface and triggers an eruption

Coulomb Stress Analysis of Halmahera Earthquake on June 7th 2016, Mw=6.3 and Its Correlation with Aftershocks Fathony Akbar Pratikno; Gazali Rachman; Bagus Jaya Santosa
IPTEK The Journal for Technology and Science Vol 30, No 2 (2019)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

Main earthquake with magnitude Mw 6.3, has been occurred in the West of Halmahera Island, Northern Molucca on June 7th, 2016. The activity of the Pacific plate, Eurasia plate and Indo-Australia plates trigger some earthquake around Halmahera. The purpose of the current study was to determine the Coulomb stress change of the main earthquake and predict the aftershocks’ location around it. For understanding an interaction of the faults, this study used Coulomb stress change model. Three component seismic waveform data recorded by TNTI station within 132 km, SANI station within 381.2 km, LUWI station within 478.3 km, and TOLI2 station within 617.6 km of the epicenter. This study used software ISOLA-GUI to obtain the parameters of the earthquake source. The parameters of the earthquake source were then used to determine fracture orientation, length, width and slip displacement. It was also used to calculate the Coulomb stress changes around the main shock, using software Coulomb 33. The result shows that the orientation of the earthquake fault has a dip angle of 48° to the horizontal plane and has a strike of 210° against the North. The fault length is 19.49 km, the fault width is 11.59 km and slip displacement is 49.43 cm. Based on plotting result, the main earthquake in Northern Molucca on June 7th, 2016 has positive Coulomb stress change that spread across the Northeast to the Southwest. This change is likely triggered three aftershocks with a range of Mw 4.7 to 6.2.

Sosialisasi Mitigasi Bencana Gempa Bumi dan Simulasi Teknologi Internet of Things (IoT) di Sekolah Madrasah Aliyah Negeri 1 Maluku Tengah Rachman, Gazali; Manuhutu, Fredrik; Jamaludin; Batlolona, John Rafafy; Nurmin; Risahondua, Hatasudji
AJAD : Jurnal Pengabdian kepada Masyarakat Vol. 4 No. 1 (2024): APRIL 2024
Publisher : Lembaga Mitra Solusi Teknologi Informasi (L-MSTI)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.59431/ajad.v4i1.300

The problem in Maluku is about earthquake mitigation and the lack of our young generation or students who master Internet of Things (IoT) technology. The reason why this issue should be a major concern is because Maluku is an earthquake-prone area. Providing understanding about earthquakes and earthquake mitigation is carried out through outreach to schools so that it is hoped that teachers and students will become pioneers who can provide understanding or knowledge about earthquakes and earthquake mitigation for each family and in their respective environments. Apart from that, mastery of IoT technology is very important. This is because IoT is the basis for creating the industrial era 4.0. The lack of knowledge about IoT technology among students in Maluku is a concern in increasing students' knowledge about IoT technology. To overcome this problem, socialization and simulation activities were carried out in schools which were partners in the Community Service Program activities in providing IoT training and the application of IoT in the industrial world. It is hoped that mastering the basic knowledge of IoT technology can support innovative IoT-based learning processes. IoT-based learning provides stimulus for students to carry out various experiments that are more innovative, creative and independent. Earthquake mitigation socialization activities and IoT technology workshop activities will be carried out at MAN 1 School, Central Maluku.

PENERAPAN DAN TANTANGAN DIMENSI BERNALAR KRITIS DAN KREATIF PADA MATA PELAJARAN MATEMATIKA DAN SAINS IPA Awan, Ali; Rachman, Gazali; Laurens, Theresia; Sanders, Rachel
Atom : Jurnal Riset Mahasiswa Vol 2 No 1 (2024): Atom: Jurnal Riset Mahasiswa
Publisher : Jurusan Pend. MIPA FKIP Universitas Pattimura

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30598/atom.2.1.23-29

Today's students must be able to optimize the dimensions of critical and creative reasoning abilities with the many digital-based learning resources that support this, especially to develop their abilities in Mathematics and Science subjects for students in class X-3 of SMP Negeri 1 Ambon, totalling 36 participants. This research aims to explore the application and challenges of critical and creative reasoning using qualitative methods with instruments like observation sheets. The research results show that most students are in good categories for the critical reasoning and creative dimensions. The critical reasoning dimension includes obtaining and processing information and ideas, analysing and evaluating reasoning, and reflecting on thought and thought processes that are in the good category. However, there is a need to improve the ability to make the right decisions. The creative dimension includes generating original ideas and producing original works and actions, which are also in the good category. However, there are challenges to increasing creative abilities to a higher level. This study also found that students' low basic abilities are the main obstacle in developing critical and creative reasoning dimensions of ability

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