PEMODELAN TIGA DIMENSI (3D) ZONA SESAR OPAK BANTUL YOGYAKARTA BERDASARKAN DATA ANOMALI BOUGUER LENGKAP

Abstract

Interpretation qualitative and quantitative have done in Opak fault area Pleret, Bantul, Yogyakarta at 7°51'12,7" LS to 7°53'54" LS and 110°22'42,5" BT to 110°25'39,8"BT according to the Bouguer anomaly complex data. The result observation shows that the heavily damaged area is the Opak fault line. Qualitative interpretation is used to Bouguer anomaly contour map analysis. The quantitative interpretation of the Opak fault can be reviewed with 2 or 3 dimensional model. Two dimensional model can be obtained from 19 slicing of anomaly Bouguer contour map. Three dimensional model can be obtained from reconstruction of 2 dimensional model according to the depth data. The qualititative interpretation of anomaly Bouguer contour map shows the linier structure over the northeast to southeast. Opak fault line indicates normal fault, where the eastern block settled (foot wall) while the western block (hanging wall) downward relatively. Quantitative interpretation from the subsurface structure modeling, we can obtain the rock density from 2.6 g/cm3 to 2.7 g/cm3, that are brecia and andesit rock. The Alluvium density is 1.85 g/cm3 as closure formation. The average depth of Opak fault line from 55 to 82 m, while the displacement between foot wall and hanging wall from 5 to 10 m.