Rate Changes detected by PBO strainmeters

by J. Langbein, USGS

A quick look at the strain changes

This page contains links to plots of strain data from the PBO borehole strainmeter network. The plots presented below explore rate changes in these data. Specifically, a period of data is selected for the previous 100 days, previous 40 days, and previous 10 days; a rate is fit to the all of the data in those time intervals and, for the last 10% of the time series (10 days, 4 days, and 1 day) a rate change is also fit. The estimated rate change is compared with its standard error. The plots are updated once per day through automated scripts.

The “stack plots” in the table below show the changes in strain in two columns; the first being the tensor strain changes in geographic coordinates; and the second column are the strain changes that have been high-passed filtered using a simple running average of 30 days; this should highlight the short term changes in strain.

Region Stack Plots
last 100 days last 40 days last 10 days
Olympic Peninsula 100 days 40 days 10 days
Southern Oregon 100 days 40 days 10 days
San Juan Bautista, Calif 100 days 40 days 10 days
Parkfield, Calif 100 days 40 days 10 days
Southern Calif 100 days 40 days 10 days
Mt St. Helens 100 days 40 days 10 days
Yellowstone 100 days 40 days 10 days

This new page represents consolidation of recent work with processing USGS borehole strainmeter data and a newer (better?) method to calibrate the PBO strainmeters. Nearly all of the scripts (programs) used to process and update these PBO data are also used to process the USGS strainmeter data. Hopefully, similarity of the scripts applied to the different data sets will result in better “up-keep” of the results presented here. Finally, both the raw and “cleaned” data should be obtained from UNAVCO.

New Item -- Plots of past transient strain changes of interest

Retrospective plots of historical transients.

Event Stack Plots of older strain data
Vancouver Island/Olymipic Peninsula; Mid to Late-May 2008 ETS May 2008 ETS
Vancouver Island/Olymipic Peninsula; Mid to Late-Jan 2007 ETS Jan 2007 ETS

PBO Strainmeter Locations

The solid triangles on the map below mark the locations of the strainmeter being monitored here. Open and smaller triangles show many (but not all) of the PBO strainmeters that I am not analyzing for a variety of reason.


  • Map of PNW PBO strainmeters


  • Map of Central Cascadia PBO strainmeters


  • San Juan Bautista, Central Calif, PBO strainmeters


  • Parkfield, Central Calif, PBO strainmeters


  • Map of Southern Calif PBO strainmeters


  • Mt St Helens PBO strainmeters


  • Yellowstone PBO strainmeters


Brief summary of processing

Each borehole strainmeter consists of 4 gauges that measure extension in four different directions. The regional strain measured by each gauge is primarily affected by the presence of the borehole, and the material used to cement the strainmeter into the borehole (about 100 to 200 meters depth). There are a number of secondary contributions that may affect the measurement, too.

Since the Earth Tide is a well known repeating source of strain, I have used both the M2 (12.42 hour period) and the O1 (25.82 hour period) to calibrate these strainmeters in terms of the dilatation (Eee + Enn), and two shear components, 2*Een and Eee - Enn. Calibration is based upon the methods outlined in the a paper by Hart et al.. There, they discuss in detail the methods when isotropic coupling can be applied to fit predicted, theoretical tensor strain tides to the tides observed on each of the strain-gages. In their appendix, Hart et al. also discuss the possibility of anisotropic coupling. For nearly all of the PBO strainmeters, the standard approach of isotropic coupling with realistic values of areal and shear coupling suggested by Hart et al. did not yield a calibration matrix such that the theoretical tides matched the observed tides. Relaxing the constraint on areal coupling provided a better fit of the calibration matrix for some sites. For other sites, however, I needed to abandoned isotropic coupling in favor of completely aniostropic coupling or, vertical anisotrophy. Finally, in some cases, B009, B012, and B018, I could not obtain a calibration matrix that matched both the observed and the theoretical tides. For both B009 and B012, they are installed within a few hundred meters of the coast where there are large, > 2 meter, variations in the local, ocean tide. Although B012 is located approximately 5KM from any inlet from Puget Sound, the tidal models that incorporate the local ocean load are probably not known to the degree needed to match the observed strain-tides.

Processing individual components of strain

Below, are plots showing the daily results of processing from each site, both the individual gauge data and the tensor components of strain. These are produced by running the processing algorithm with the option to use prior estimates of the tides and pressure coefficents. Seen in the plots are the raw strain data (grey), the atmospheric pressure data rescaled to by the pressure coefficient (green), the strain data adjusted for changes in the pressure (blue), and the residual strain after the Earth Tides have been removed (red). The strain data have had a linear trend removed. The black, dashed line is the linear trend and a change in rate for the last 10% of the time span plotted. Finally, the top graph is a plot of the first differences of the residual strain data normalized to the expected drift in the data; the “dot plot” is useful for detecting offsets and outliers in the strain data.

Station PLOTS
Channel 0 Channel 1 Channel 2 Channel 3 Dil 2 Een Eee - Enn Instrument Dil 1 Instrument DIL 2 Instrument DIF shr 1 Instrument DIF shr 2 Instrument Shear 1 Instrument Shear 2
B003/P403 CH0 CH1 CH2 CH3 DIL 2Een Eee - Enn BH DIL1 BH DIL2 BH DIF 1 BH DIF 2 BH Shear 1 BH Shear 2
B004 CH0 CH1 CH2 CH3 DIL 2Een Eee - Enn BH DIL1 BH DIL2 BH DIF 1 BH DIF 2 BH Shear 1 BH Shear 2
B005 CH0 CH1 CH2 CH3 DIL 2Een Eee - Enn BH DIL1 BH DIL2 BH DIF 1 BH DIF 2 BH Shear 1 BH Shear 2
B007 CH0 CH1 CH2 CH3 DIL 2Een Eee - Enn BH DIL1 BH DIL2 BH DIF 1 BH DIF 2 BH Shear 1 BH Shear 2
B009 CH0 CH1 CH2 CH3 DIL 2Een Eee - Enn BH DIL1 BH DIL2 BH DIF 1 BH DIF 2 BH Shear 1 BH Shear 2
B012 CH0 CH1 CH2 CH3 DIL 2Een Eee - Enn BH DIL1 BH DIL2 BH DIF 1 BH DIF 2 BH Shear 1 BH Shear 2
B014 CH0 CH1 CH2 CH3 DIL 2Een Eee - Enn BH DIL1 BH DIL2 BH DIF 1 BH DIF 2 BH Shear 1 BH Shear 2
B018 CH0 CH1 CH2 CH3 DIL 2Een Eee - Enn BH DIL1 BH DIL2 BH DIF 1 BH DIF 2 BH Shear 1 BH Shear 2
B022 CH0 CH1 CH2 CH3 DIL 2Een Eee - Enn BH DIL1 BH DIL2 BH DIF 1 BH DIF 2 BH Shear 1 BH Shear 2
B027 CH0 CH1 CH2 CH3 DIL 2Een Eee - Enn BH DIL1 BH DIL2 BH DIF 1 BH DIF 2 BH Shear 1 BH Shear 2
B028 CH0 CH1 CH2 CH3 DIL 2Een Eee - Enn BH DIL1 BH DIL2 BH DIF 1 BH DIF 2 BH Shear 1 BH Shear 2
B035 CH0 CH1 CH2 CH3 DIL 2Een Eee - Enn BH DIL1 BH DIL2 BH DIF 1 BH DIF 2 BH Shear 1 BH Shear 2
B036 CH0 CH1 CH2 CH3 DIL 2Een Eee - Enn BH DIL1 BH DIL2 BH DIF 1 BH DIF 2 BH Shear 1 BH Shear 2
B058 CH0 CH1 CH2 CH3 DIL 2Een Eee - Enn BH DIL1 BH DIL2 BH DIF 1 BH DIF 2 BH Shear 1 BH Shear 2
B065 CH0 CH1 CH2 CH3 DIL 2Een Eee - Enn BH DIL1 BH DIL2 BH DIF 1 BH DIF 2 BH Shear 1 BH Shear 2
B073 CH0 CH1 CH2 CH3 DIL 2Een Eee - Enn BH DIL1 BH DIL2 BH DIF 1 BH DIF 2 BH Shear 1 BH Shear 2
B078 CH0 CH1 CH2 CH3 DIL 2Een Eee - Enn BH DIL1 BH DIL2 BH DIF 1 BH DIF 2 BH Shear 1 BH Shear 2
B079 CH0 CH1 CH2 CH3 DIL 2Een Eee - Enn BH DIL1 BH DIL2 BH DIF 1 BH DIF 2 BH Shear 1 BH Shear 2
B081 CH0 CH1 CH2 CH3 DIL 2Een Eee - Enn BH DIL1 BH DIL2 BH DIF 1 BH DIF 2 BH Shear 1 BH Shear 2
B084 CH0 CH1 CH2 CH3 DIL 2Een Eee - Enn BH DIL1 BH DIL2 BH DIF 1 BH DIF 2 BH Shear 1 BH Shear 2
B086 CH0 CH1 CH2 CH3 DIL 2Een Eee - Enn BH DIL1 BH DIL2 BH DIF 1 BH DIF 2 BH Shear 1 BH Shear 2
B087 CH0 CH1 CH2 CH3 DIL 2Een Eee - Enn BH DIL1 BH DIL2 BH DIF 1 BH DIF 2 BH Shear 1 BH Shear 2
B201 CH0 CH1 CH2 CH3 DIL 2Een Eee - Enn BH DIL1 BH DIL2 BH DIF 1 BH DIF 2 BH Shear 1 BH Shear 2
B203 CH0 CH1 CH2 CH3 DIL 2Een Eee - Enn BH DIL1 BH DIL2 BH DIF 1 BH DIF 2 BH Shear 1 BH Shear 2
B206 CH0 CH1 CH2 CH3 DIL 2Een Eee - Enn BH DIL1 BH DIL2 BH DIF 1 BH DIF 2 BH Shear 1 BH Shear 2
B944 CH0 CH1 CH2 CH3 DIL 2Een Eee - Enn BH DIL1 BH DIL2 BH DIF 1 BH DIF 2 BH Shear 1 BH Shear 2

Comparison of current and prior analysis of strain data

The following presents output of cleanstrain+ for the most recent 100 days and results from analysis of a previous 100-day chunk of strain data. For the comparison of pressure and tides, a pdf table is provided which lists all of the estimates for the pressure and 4 Tidal constituents. Please note that I only present the analysis for the gage data and not for the components of strain to minimize space.

Station Table Plots
B003 CH0 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B003 CH1 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B003 CH2 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B003 CH3 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B004 CH0 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B004 CH1 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B004 CH2 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B004 CH3 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B005 CH0 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B005 CH1 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B005 CH2 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B005 CH3 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B007 CH0 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B007 CH1 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B007 CH2 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B007 CH3 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B009 CH0 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B009 CH1 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B009 CH2 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B009 CH3 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B012 CH0 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B012 CH1 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B012 CH2 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B012 CH3 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B014 CH0 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B014 CH1 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B014 CH2 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B014 CH3 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B018 CH0 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B018 CH1 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B018 CH2 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B018 CH3 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B022 CH0 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B022 CH1 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B022 CH2 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B022 CH3 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B027 CH0 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B027 CH1 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B027 CH2 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B027 CH3 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B028 CH0 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B028 CH1 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B028 CH2 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B028 CH3 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B035 CH0 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B035 CH1 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B035 CH2 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B035 CH3 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B036 CH0 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B036 CH1 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B036 CH2 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B036 CH3 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B058 CH0 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B058 CH1 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B058 CH2 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B058 CH3 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B065 CH0 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B065 CH1 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B065 CH2 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B065 CH3 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B073 CH0 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B073 CH1 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B073 CH2 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B073 CH3 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B078 CH0 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B078 CH1 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B078 CH2 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B078 CH3 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B079 CH0 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B079 CH1 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B079 CH2 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B079 CH3 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B081 CH0 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B081 CH1 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B081 CH2 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B081 CH3 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B084 CH0 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B084 CH1 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B084 CH2 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B084 CH3 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B086 CH0 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B086 CH1 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B086 CH2 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B086 CH3 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B087 CH0 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B087 CH1 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B087 CH2 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B087 CH3 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B201 CH0 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B201 CH1 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B201 CH2 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B201 CH3 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B203 CH0 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B203 CH1 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B203 CH2 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B203 CH3 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B206 CH0 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B206 CH1 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B206 CH2 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B206 CH3 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B944 CH0 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B944 CH1 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B944 CH2 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis
B944 CH3 Compare pressure and tidal PSD of prior PSD of current prior analysis current analysis