M. Gamal
Kelompok Keilmuan Geodesi FITB ITB

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Deformasi Koseismik dan Pascaseismik Gempa Yogyakarta 2006 dari Hasil Survei GPS Abidin, Hasanuddin Z.; Andreas, H.; Meilano, I.; Gamal, M.; Gumilar, I.; Abdullah, C. I.
Indonesian Journal on Geoscience Vol 4, No 4 (2009)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1158.056 KB) | DOI: 10.17014/ijog.v4i4.87

Abstract

DOI: 10.17014/ijog.v4i4.87The Yogyakarta earthquake of 27 May 2006 occurred at 05:54 WIB with magnitude of 6.4 Mw. It shaked the region of Bantul, Yogyakarta, Sleman and Klaten for about 60 seconds. A week after the earthquake, i.e. 4-8 June 2006, a GPS survey was conducted on 48 GPS points belonging to the 2nd order national cadastral control network located in the earthquake affected region. The 2nd survey was conducted on 21-26 January 2008. The surveys were conducted using 14 dual-frequency geodetic type receivers and the Bernese 5.0 scientific software was used for data processing. The results of GPS surveys show that horizontal components of the co-seismic deformation of earthquake are generally about 10-15 cm or smaller. The GPS-derived displacement vectors and depths of aftershocks suggested the existence of left-lateral fault, with strike and dip angles of about 48o and 89o, located at about 5-10 km east of Opak Fault which is usually drawn along the Opak River. GPS surveys also estimate that horizontal components of the post-seismic deformation of Yogyakarta earthquake are about 0.3 to 9.1 cm between June 2006 and June 2008. While the co-seismic deformation shows the sinistral displacement, the post-seismic deformation indicates the dextral displacement of the eastern region of Opak Fault (Gunung Kidul area) which is relative to a more stable western region.
Mapping And Evaluating The Impact Of Land Subsidence In Semarang (Indonesia) Gumilar, Irwan; Z. Abidin, Hasanuddin; P. Sidiq, Teguh; Andreas, H.; Maiyudi, R.; Gamal, M.; Fukuda, Y.
Indonesian Journal of Geospatial Vol 2, No 2 (2013)
Publisher : Indonesian Journal of Geospatial

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Abstract

Abstract. Semarang is the capital of Central Java province, located in the northern coast of Java island, Indonesia. Land subsidence in Semarang has been widely reported and its impacts can be seen already in daily life. Based on the estimation from Levelling, Interferometric Synthetic Aperture Radar (InSAR), Microgravity and Global Positioning System (GPS) survey methods, land subsidence with rates of up to about 19 cm/year were observed during the period of 1999 up to 2011. Results derived from GPS since 2008 up to 2011 show that land subsidence in Semarang has spatial and temporal variations, with spatial average rates of about 6 to 7 cm/year.Based on the site visit surveys, the impacts of land subsidence can be seen in several forms such as cracks in buildings, damage of infrastructure (road and bridges), tilting and damaged houses, and wider expansion of coastal flooding (tidal flooding). Tidal flooding and tilting and damaged houses frequently occurs in the area where the subsidence rate is high (northern part of Semarang). Cracks in buildings and damage of infrastructure (road and bridges) occur in the boundary of large subsidence area and the less. Keywords : GPS , land subsidence, damages, coastal flooding, Semarang 
Deformation Study Of Darma Dam Using GPS Survey Method Gumilar, Irwan; Z. Abidin, Hasanuddin; Andreas, H.; P. Sidiq, Teguh; Gamal, M.; Irsyam, M.; Sadisun, I.A.
Indonesian Journal of Geospatial Vol 2, No 2 (2013)
Publisher : Indonesian Journal of Geospatial

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (942.441 KB)

Abstract

Abstract. Darma Dam is located in the Village, District Kadugede, Kuningan regency, West Java, is a combination of the type heap dam (rockfill) and homogeneous soil deposits. Darma dam holds the potential disaster similar to the disaster Situ Gintung, Tangerang, which claimed hundreds of people. In fact, its potential is much more dangerous, if not anticipated. Darma dam is located in the hills, so that there is automatic in the area underneath paddies, plantations, and residential population that stretches from Kab. Kuningan, Kab. Cirebon, to Brebes, Central Java. Seeing the potential dangers posed by Darma then it should dam was monitored his activities as one of the main ways to mitigate catastrophic collapse of the dam. One of the main methods used to monitor the activity of the dam is deformation using methods that are used to monitor the deformation of the dam is with a survey method GPS (Global Positioning System). GPS surveys have been carried out for dam deformation monitoring Darma on December 9 to 10 May 2009 and 8 to 9 September 2009. GPS survey conducted in 19 point geodetic GPS receivers using two-frequency type. GPS survey detects horizontal and vertical deformation of the monitoring points around the dam Darma, in the order of a few mm in a period of about 5 months. Horizontal movements tend Dam Darma reservoir leads to the outside (away from the water), while for vertical shift seems not so clear (some point to decline (subsidence) and several point increase (uplift)). This study is expected to provide better information on the characteristics of dam deformation Darma. By understanding these characteristics, it can be analyzed potential catastrophic dam collapse Darma in this area and mitigation mechanisms can also be planned. Keywords : GPS, dams, deformationAbstract. Darma Dam is located in the Village, District Kadugede, Kuningan regency, West Java, is a combination of the type heap dam (rockfill) and homogeneous soil deposits. Darma dam holds the potential disaster similar to the disaster Situ Gintung, Tangerang, which claimed hundreds of people. In fact, its potential is much more dangerous, if not anticipated. Darma dam is located in the hills, so that there is automatic in the area underneath paddies, plantations, and residential population that stretches from Kab. Kuningan, Kab. Cirebon, to Brebes, Central Java. Seeing the potential dangers posed by Darma then it should dam was monitored his activities as one of the main ways to mitigate catastrophic collapse of the dam. One of the main methods used to monitor the activity of the dam is deformation using methods that are used to monitor the deformation of the dam is with a survey method GPS (Global Positioning System). GPS surveys have been carried out for dam deformation monitoring Darma on December 9 to 10 May 2009 and 8 to 9 September 2009. GPS survey conducted in 19 point geodetic GPS receivers using two-frequency type. GPS survey detects horizontal and vertical deformation of the monitoring points around the dam Darma, in the order of a few mm in a period of about 5 months. Horizontal movements tend Dam Darma reservoir leads to the outside (away from the water), while for vertical shift seems not so clear (some point to decline (subsidence) and several point increase (uplift)). This study is expected to provide better information on the characteristics of dam deformation Darma. By understanding these characteristics, it can be analyzed potential catastrophic dam collapse Darma in this area and mitigation mechanisms can also be planned. Keywords : GPS, dams, deformationÂ