ANOMALI GAYA BERAT, KEGEMPAAN SERTA KELURUSAN STRUKTUR GEOLOGI DAERAH JOGJAKARTA DAN SEKITARNYA
The region of Jogjakarta and the surrounding area which are generaly covered by young sediment, consist of aluvium and volcanic deposits. Because of this phenomenon, lateral and vertical distribution of geological structural element are still unknown. Therefore, gravity data analysis is a good tool to delineate geological structural element burried by young sediment
deposits. Regional and local geological structural lineaments which are detected by Bouguer and residual gravity anomaly analyses, inform that deformation processes have occurred intensively in this area. The occurrences of east-west trending fold and northeast-southwest trending thrust fault, northwest-southeast trending strikeslip fault, and north-south trending normal fault indicate that deformation process was caused by north-south compressional principal stress generated by subduction Eurasian plate and Indo-Australian plate. Gravity modelling analysis of AB and CD sections indicate the presence of strike slip fault, thrust fault and normal fault within the basement and Tertiary rocks. Several faults, such as Bogowonto, Nanggulan, Sentolo, Imogiri and Opak Faults, are interpreted to be reactivated and faulted the Quarternary deposits. Earthquake hazard that took place in Jogjakarta and th surrounding area on May 27 , 2006 by the reactivation of Opak Fault. Referring to this experience, the study of active faults in this area is necessary.
ÂKeywords : anomaly, gravity, geological structure, earthquake
Http:/neic.usgs.gov/neis/eq_depot/2006/eq_060526_neb6/neic_neb6_h.html :3 pp.
Nainggolan, D.A., Sardjono dan Mubroto, B., 1997. Peta Anomali Bouguer Lembar Surabaya, skala 1:1.000.000 Indonesia. Pusat Penelitian dan Pengembangan Geologi Bandung.
Ratman, N., Suwarti, T. dan Samodera, H., 1993. Peta Geologi Indonesia, Lembar Surabaya, skala 1:1.000.000. Pusat Penelitian dan Pengembangan Geologi Bandung.
Sopaheluwakan, J., 1977. Ringkasan peristiwa-peristiwa tektonik pada batuan Andesit tua di selatan Jawa Timur. Riset Geologi dan Pertambangan 1(1): 34-41.
Sudradjat, A., 1975. Batuan Gunung api dan Struktur Geologi di Jawa Bagian Timur dan Nusatenggara Bagian Barat. Geol. Indonesia 2(3):19-22.
Talwani, M., Worzel, J.L and Lansman, M. 1959. Rapid Gravity computation of two-dimentional bodies with application to Mendocino submarine fracture zone. Journal of Geophysical Research 64:49-59.
Telford, W.M., R.E. Sheriff, L.P. Geldart and D.A. Keys, 1976. Applied Geophysics. Cambridge University Press, London, 858 p.
Won, I.J. and Bevis, M.G. 1987. Computing the gravitational and magnetic anomalies due to a polygon : algoritma and fortran subroutines. Geophysics 52(2):232-238.
Zen, M.T., Alswar, M., Simatupang, S.H, dan Yuniarto, G., 1983. Tektogenesa-Gravitasi dan Daur Magmatik di Sepanjang deretan Volkanik Ungaran-Merapi di Jawa Tengah. Kertas Karya PIT IAGI ke XII, Jogjakarta.
Authors who publish articles inÂ Jurnal Geologi dan Sumberdaya Mineral (JGSM.Geologi) agree to the following terms:
- Authors retain copyright of the article and grant the journal right of first publication with the work simultaneously licensed under aÂ CC-BY-NC or The Creative Commons Attributionâ€“ShareAlike License.
- Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgment of its initial publication in this journal.
- Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work (See The Effect of Open Access)