Engineering topics

Jackson, David D.

Publications and source records attributed to Jackson, David D..

6 records

NASA NTRS1993

Space geodetic measurement of crustal deformation in central and southern California, 1984-1992

We estimate the velocity field in central and southern California using Global Positioning System (GPS) observations from 1986 to 1992 and very long baseline interferometry (VLBI) observations from 1984 to 1991. Our core network includes 12 GPS sites spaced approximately 50 km apart, mostly in the western Transverse Ranges and the coastal Borderlands. The precision and accuracy of the relative horizontal velocities estimated for these core stations are adequately described by a 95% confidence ellipse with a semiminor axis of approximately 2 mm/yr oriented roughly north-south, and a semimajor axis of approximately 3 mm/yr oriented east-west.

Feigl, Kurt L.↗

NASA NTRS1993

Tectonic deformation in southern California

Our objectives were to use modem geodetic data, especially those derived from space techniques like Very Long Baseline Interferometry (VLBI), Satellite Laser Ranging (SLR), and the Global Positioning System (GPS) to infer crustal deformation in southern California and relate it to plate tectonics and earthquake hazard. To do this, we needed to collect some original data, write computer programs to determine positions of survey markers from geodetic observables, interpret time dependent positions in terms of velocity and earthquake caused episodic displacements, and construct a model to explain these velocities and displacements in terms of fault slip and plate movements.

Jackson, David D.↗

NASA NTRS1993

Plate tectonics and crustal deformation around the Japanese Islands

We analyze over a century of geodetic data to study crustal deformation and plate motion around the Japanese Islands, using the block-fault model for crustal deformation developed by Matsu'ura et al. (1986). We model the area including the Japanese Islands with 19 crustal blocks and 104 faults based on the distribution of active faults and seismicity. Geodetic data are used to obtain block motions and average slip rates of faults. This geodetic model predicts that the Pacific plate moves N deg 69 +/- 2 deg W at about 80 +/- 3 mm/yr relative to the Eurasian plate which is much lower than that predicted in geologic models. Substantial aseismic slip occurs on the subduction boundaries. The block containing the Izu Peninsula may be separated from the rigid part of the Philippine Sea plate. The faults on the coast of Japan Sea and the western part of the Median Tectonic Line have slip rates exceeding 4 mm/yr, while the Fossa Magna does not play an important role in the tectonics of the central Japan. The geodetic model requires the division of northeastern Japan, contrary to the hypothesis that northeastern Japan is a part of the North American plate. Owing to rapid convergence, the seismic risk in the Nankai trough may be larger than that of the Tokai gap.

Hashimoto, Manabu↗

NASA NTRS1993

Global positioning system reoccupation of early triangulation sites - Tectonic deformation of the Southern Coast Ranges

We study tectonic deformation in the Southern Coast Range, California. We use triangulation and astronomic azimuth data collected since 1875, trilateration since 1970, and global positioning system data collected from 1986 to 1987. Two modeling techniques have been used. An elastic block-fault model is applied to study the tectonic motion of the San Andreas Fault and the San Gregorio-Hosgri Fault. Station velocities are modeled to study regional deformations. Results show that the regional deformation is predominantly controlled by deep strike-slip motion along the San Andreas Fault, at a rate of 33 +/- 2 mm/yr. Deep slip along the San Gregorio-Hosgri Fault is about 0-4 mm/yr, assuming a locked suit to a depth of 20 km. Convergence normal to the San Andreas Fault in the Southern Coast Ranges is not greater than 0.02 microrad/yr.

Shen, Zheng-Kang↗

NASA NTRS1988

Geodetic evidence of the seismic potential at Parkfield, California

The average rates of line-length change and the rates of the shallow fault slip observed near Parkfield, California, were used to estimate the slip rate at depth on the San Andreas fault (SAF), using the Matsu'ura et al. (1986) procedure to model the aseismic deformation as a perturbation to steady block motion across the SAF. Five different models were tested against the data, with one model, featuring a nearly monotonic transition from creeping behavior on the northwest to locked behavior on the southeast, found to fit the data acceptably well. It is shown that stored elastic energy southeast of Parkfield could produce an earthquake of magnitude up to 8.0, that would have displacement and rupture length similar to historic earthquakes of the same size.

Sung, Li-Yu↗

NASA NTRS1986

Dislocation model for aseismic crustal deformation at Hollister, California

A model of crustal deformation during the interseismic phase is developed and applied (using the improved Bayesian inversion algorithm described by Jackson and Matsu'ura, 1985) to trilateration data for the USGS Hollister (CA) network. In the model, rigid blocks in motion relative to each other experience friction only in a brittle upper zone, while their ductile lower zones slide freely; the Hollister model comprises five blocks and nine rectangular fault patches. The data and results are presented in tables, graphs, and maps and characterized in detail. The model predicts steady block motion on time scales between 10 yr and 1 Myr, with net motion across the San Andreas/Calaveras fault system 38 + or - 3 mm/yr and brittle/ductile transition depths ranging from 0.4 to 11 km. Two San Andreas segments with higher probabilities of moderate-to-large earthquakes are identified.

Matsuura, Mitsuhiro↗