DISCLAIMER: The plots and processed data on this site are generated using methods that are under development. They should not be used for engineering, legal, or any other critical applications.
The plot is based on data collected by the NSF-funded Plate Boundary Observatory (PBO). 1 sample-per-second data were downloaded from the IRIS BUD database. They were downsampled to one point every 5 minutes using a median filter and linearized using the same formula employed by PBO. Data have been hand-edited to remove obvious outliers and steps; these corrections may be different from those applied by PBO. Borehole strainmeter data contain strong nonlinear trends caused by borehole deformation and other non-tectonic processes very local to the instrument. These trends have been removed from the data shown in these plots by fitting and subtracting a function containing a linear, a quadratic, and an exponential term from the entire data record shown here. This is not the same as the detrending method used by PBO.
At this time all gauges are weighted equally and no tidal calibration has been applied.
3gekk=average of the three gauges that are spaced 120 degrees apart, proportional to areal strain
2gekk=average of the 2 perpendicular gauges, proportional to areal strain
These two time series should agree closely when gauges are appropriately weighted
.LDO is atmospheric pressure.
B018 is recording a strain event beginning around January 15, 2007. The close agreement of 3gekk and 2gekk implies that it is reasonable to weight the gauges equally, although these two time series seem to be disagreeing more since about 20 January 2007. The areal strain time series are dominated by an atmospheric pressure response. The strain event appears most distinctly in the shear strain time series.