The errors in secular rate include an estimate Strain and co-seismic strain where all parameters are estimated Tabulated below are the estimates of secular Uniformity in rate of strain are the large, co-seismic changes from the Modeled using spatially and temporally uniform strain. The changes in length of each baseline from each network can be adequately The strain analysis neglects the motion of the central monument. Of the central monument from that of changes in strain. With seven baselines, it is difficult to resolve the contribution of wobble Since this network consists of two, radial networks, each North-south direction, and Een is tensor shear on either a north-south orĮast-west plane. The strain changes that are plotted are reckoned such thatĮee is extension in the east-west direction, Enn is extension in the So, the results of the strain analysis neglects the motionĪNZA: Measurements of this network that straddles the San Jacinto fault To resolve the contribution of wobble of the central monument from that ofĬhanges in strain. More-or-less a fan-shaped array rather than a radial network, it is difficult Shear on either a north-south or east-west plane. That are plotted are reckoned such that Eee is extension in the east-westĭirection, Enn is extension in the north-south direction, and Een is tensor PINON FLAT: Measurements of this network started in 1986. Tensor, the displacement of the central monument is also estimated as a Network is highly redundant for estimating the 3 components of the strain Tensor shear on a plane parallel with the San Andreas fault. Parallel strain is extension parallel with the local strike of the SanĪndreas fault, N65W, normal strain is extension N25E, and shear strain is the The strain changes that are plotted are reckoned such that Redundant for estimating the 3 components of the strain tensor, theĭisplacement of the central monument is also estimated as a function of time.īUTTES: Measurements of this network located north of Pearblossom by 40 Km On a plane parallel with the San Andreas fault. N65W, normal strain is extension N25E, and shear strain is the tensor shear Strain is extension parallel with the local strike of the San Andreas fault, The strain changes that are plotted are reckoned such that parallel Of the 12 baseline network have been made approximately 3 to 4 times each Linearly with time over 2-week intervals. The strainĬhanges estimated for the first several years assume that strain changes This network straddles the San Andreas fault. PEARBLOSSOM: Data starts in late 1980 when measurements were made several The secular rates have been removed from the strain data and the rates are The date of the Landers earthquake is specified as a reference date and theĮrror grows in time relative to this date. Random walk motions of each geodetic monument of approximately 1 mm/sqrt(yr). The error accounts for the instrument precision of 0.1ppm and the The error bars represent one standard deviation about the estimate of strainĬhange. In general, the vertical line denotes the time of the 1992 Landers Of strain changes from the Pinon Flat network Of strain changes from the Buttes network Of strain changes from the Pearblossom network Make distance measurements on approximately one dozen baselines. Person crew to be on-site to run the instrument and set-up the reflectors to Each measurement of strain requires a 3 to 4 Times per year but the measurements at Anza and at the Buttes are madeĪpproximately once per year. Measurements at Pinon Flat and Pearblossom are made approximately 3 to 4 The maps of the networks show the location of the baselines in red, the majorįaults with dark, heavy lines, and other faults with thin lines. Geodetic monuments limit the ultimate precision in our estimate of strain These measurements is 0.1 part-per-million, but localized wobble of the Surface, aseismic slip is not apparent, these radial networks are idealįor measuring the 3 components of the tensor strain. These networks are radial withĪpproximately 12 baselines using a common, central station. This map shows the locations of 4 two-color EDM (Electronic Distance The San Andreas fault system in this region. Four EDM networks located in Southern California show strain accumulation on
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