F. Krumm

Bio: F. Krumm is an academic researcher from University of Stuttgart. The author has contributed to research in topics: Plate tectonics & Equator. The author has an hindex of 6, co-authored 10 publications receiving 130 citations.

Graph, graph spectra and partitioning algorithms in a geodetic network structural analysis and adjustment

Abstract: Graph theory and its algorithms have been applied in geodesy, viz, structural analysis of networks, and sparse matrix technique in geodetic network adjustment. Fundamental in these applications is the representation of the geodetic network as a graph. Adjacency matrix and the spectra of the Laplacian matrix are shown to have useful properties for both structural analysis and partitioning of a geodetic network. Algorithms for the construction of adjacency matrix, structural analysis, and partitioning of a geodetic network are presented.

Did a change in tectonic regime occur between the Phanerozoic and earlier Epochs

Abstract: A compilation of palaeogeographical maps of the Neo Proterozoic (Ptz) and Phanerozoic (Pz) 0.6 Ga BP to the present is analyzed in the terms of the (a) ratio between continental to oceanic crust areas (in short continent-to-ocean ratio), (b) length of spreading centres and (c) length of subduction zones. The variation of these tectonic processes is then compared to the variations occurred during the Archean (Arc 3.8–2.5 Ga BP) and Proterozoic (Ptz 2.5–0.54 Ga BP). The discussion takes the geomagnetic field and changes in length of the day (LOD) into account as well. From the constancy of the continent-to-ocean ratio through Pz and from the small size of the continental area above sea level in Neoproterozoic it follows that at the border between Ptz and Pz there has been a large change of the length of the shelf zones. This change can explain contemporary change of the despinning rate from about 0.35 to about 1.79 ms/century. In general, our findings suggest a change in tectonic regime at the border between Ptz and Pz.

Robust estimation of geodetic datum transformation

Abstract: The robust estimation of geodetic datum transformation is discussed. The basic principle of robust estimation is introduced. The error influence functions of the robust estimators, together with those of least-squares estimators, are given. Particular attention is given to the robust initial estimates of the transformation parameters, which should have a high breakdown point in order to provide reliable residuals for the following estimation. The median method is applied to solve for robust initial estimates of transformation parameters since it has the highest breakdown point. A smooth weight function is then used to improve the efficiency of the parameter estimates in successive iterative computations. A numerical example is given on a datum transformation between a global positioning system network and the corresponding geodetic network in China. The results show that when the coordinates are contaminated by outliers, the proposed method can still give reasonable results.

Polarized Plate Tectonics

Abstract: The mechanisms driving plate motion and the Earth's geodynamics are still not entirely clarified. Lithospheric volumes recycled at subduction zones or emerging at rift zones testify mantle convection. The cooling of the planet and the related density gradients are invoked to explain mantle convection either driven from the hot interior or from the cooler outer boundary layer. In this paper we summarize a number of evidence supporting generalized asymmetries along the plate boundaries that point to a polarization of plate tectonics. W-directed slabs provide two to three times larger volumes to the mantle with respect to the opposite E- or NE-directed subduction zones. W-directed slabs are deeper and steeper, usually characterized by down-dip compression. Moreover, they show a shallow decollement and low elevated accretionary prism, a steep regional monocline with a deep trench or foredeep, a backarc basin with high heat flow and positive gravity anomaly. Conversely directed subduction zones show antithetic signatures and no similar backarc basin. Rift zones also show an asymmetry, e.g., faster Vs in the western lithosphere and a slightly deeper bathymetry with respect to the eastern flank. These evidences can be linked to the westward drift of the lithosphere relative to the underlying mantle and may explain the differences among subduction and rift zones as a function of their geographic polarity with respect to the “tectonic equator.” Therefore also mantle convection and plate motion should be polarized. All this supports a general tuning of the Earth's geodynamics and mantle convection by astronomical forces.