Workshop on Computational Tectonics (original) (raw)
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Computational tools have become a standard in the discipline of architecture, in that extent we can think of a saturation of the field with computational tools. From early design stages, to visualization to the execution of building designs, every aspect of the industry is dominated by the use of computers and software. Insofar computational tools do not form the exception but have become today´s standard, the rule, the norm. The consequence is not necessarily the omnipresence of sophisticated applications, on the contrary the predominant method relies on the translation of conventional, pre-digital, design methods such as the drafting of plans and sections and visualization of preconceived ideas. This can be described as computerized methods in contrast to the opposite end of the spectrum which relies on computational ideas. These will be the field of inquiry for this paper.
Easy handling of tectonic data: the programs TectonicVB for Mac and TectonicsFP for Windows™
Computers & Geosciences, 2002
TectonicVB for Macintosh and TectonicsFP for Windows TM operating systems are two menu-driven computer programs which allow the shared use of data on these environments. The programs can produce stereographic plots of orientation data (great circles, poles, lineations). Frequently used statistical procedures like calculation of eigenvalues and eigenvectors, calculation of mean vector with concentration parameters and confidence cone can be easily performed. Fault data can be plotted in stereographic projection (Angelier and Hoeppener plots). Sorting of datasets into homogeneous subsets and rotation of tectonic data can be performed in interactive two-diagram windows. The paleostress tensor can be calculated from fault data sets using graphical (calculation of kinematic axes and right dihedra method) or mathematical methods (direct inversion or numerical dynamical analysis). The calculations can be checked in dimensionless Mohr diagrams and fluctuation histograms. r
Deckers J et al Tectonophysics
A B S T R A C T The Grote Brogel Fault (GBF) is a major WNW-ESE striking normal fault in Belgium that diverges westward from the NW-SE striking western border fault system of the Roer Valley Graben. The GBF delimits the topographically higher Campine Block from the subsiding Roer Valley Graben, and is expressed in the Digital Terrain Model (DTM) by relief gradients or scarps. By integrating DTM, Electrical Resistivity Tomography (ERT), Cone Penetration Test (CPT) and borehole data, we studied the Quaternary activity of the GBF and its effects on local hydrogeology. In the shallow subsurface (< 50 m) underneath these scarps, fault splays of the GBF were interpreted on newly acquired ERT profiles at two investigation sites: one on the eastern section and the other on the western section, near the limit of the visible surface trace of the fault. Borehole and CPT data enabled stratigraphic interpretations of the ERT profiles and thereby allowed measuring vertical fault offsets at the base of Pleistocene fluvial deposits of up to 12 m. Groundwater measurements in the boreholes and CPTs indicate that the GBF acts as a hydrologic boundary that prevents groundwater flow from the elevated footwall towards the hangingwall, resulting in hydraulic head differences of up to 12.7 m. For the two investigation sites, the hydraulic head changes correlate with the relief gradient, which in turn correlates with the Quaternary vertical offset of the GBF. ERT profiles at the eastern site also revealed a local soft-linked stepover in the shallow sub-surface, which affects groundwater levels in the different fault blocks, and illustrates the complex small-scale geometry of the GBF.
The Tonga Wadati-Benioff zone is characterized by a large seismicity gap beneath the Lau Basin that raises the question of the slab continuity between the shallow to intermediate part (60-300 km) and the deep part (400-700 km). To address this problem, we investigated the Wadati-Benioff Zone geometry and stress regime through a detailed analysis of the spatial distribution of moment tensors and variation of the stress tensor, using the global seismicity [Engdahl, E., Van der Hilst, R., Buland, R., 1998. Global teleseismic earthquake relocation with improved travel times and procedures for depth determination. Bull. Seism. Soc. Am. 88, 722-743.] and the Centroid Moment Tensor solutions (CMT) catalogs [Dziewonski, A.M., Chou, T., Woodhouse, J.H., 1981. Determination of earthquake source parameters from waveform data for studies of global and regional seismicity. J. Geophys. Res. 86, 2825Res. 86, -2852. The stress tensors were computed using the Gephart's program . An improved method for determining the regional stress tensor using earthquake focal mechanism data: application to the San Fernando earthquake sequence. J. Geophys. Res. 89,[9305][9306][9307][9308][9309][9310][9311][9312][9313][9314][9315][9316][9317][9318][9319][9320]. The stress inversion results indicate that between 21°S and 27°S, and depths down to 700 km the slab is under homogeneous down dip compressional stress regime, while north of 21°S we found strong variations of the stress orientations between the intermediate and deep portions of the slab. We also show that between 14°and 19°S, the stresses at intermediate depth (60-300 km) can be resolved into two slab parallel domains, a thin upper part of the slab that is under downdip compression and the lower part that is under downdip extension. This pattern of two zones with opposite mechanical behavior is characteristic of a subducted plate with a free lower limit that does not interact with the 670-km depth boundary. These results together with the large seismicity gap within the slab argue for a slab detachment.
Do Couto et al., 2014, Tectonics, 33, 7, 1360-1385
The formation of sedimentary basins in the Alboran domain is associated with the exhumation of metamorphic core complexes over a circa 15 Ma period through a transition from regional late-orogenic extension to compression. An integrated study coupling field analysis and gravity data acquisition was performed in the Sorbas basin in the southeastern Betic Cordillera. Detailed field observations revealed for the first time that extensional tectonics occurred before shortening in this basin. Two extensional events were recorded with NW-SE to N-S and NE-SW kinematics, respectively; the first of which being likely responsible for the basin initiation. Tectonic inversion of the basin then occurred around 8 Ma in an overall approximately N-S shortening context. Two-dimensional gravity sections reveal that the basin acted as an active depocenter as the basin floor locally exceeding 2 km depth is characterized by a marked asymmetric architecture. Based on this integrated study, we explore a new evolutionary scenario which can be used as a basis for interpretations of the Neogene tectonic history of the southeastern Betics.