Data collection for CS-D Experiment in Mont Terri

Abstract

## Introduction ## This directory contains six files, four DSS files (one for each monitoring borehole in the CS-D niche in the Mont Terri Lab, Switzerland, that was interrogated for DSS during the gallery excavation), one containing the SIMFIP dataset, and the final containing them potentiometer data. There is also a subdirectory containing the points that define each of the seven boreholes in the CS-D experiment. The Easting and Northing components are relative to the ch1903 coordinate system (EPSG:2056). The final column is depth along the borehole, which is not to be confused with depth vertically below the gallery or the earth's surface. ################ ### DSS data ### ################ The DSS data span the period of 5-22-2019 16:43:54 to 6-4-2019 17:14:33, which includes the onset of deformation related to excavation and runs until roughly a week after breakthrough. Each file is formatted as NetCDF: https://www.unidata.ucar.edu/software/netcdf/ which is a self-describing binary file format. It originated in the geosciences and is used for array-based measurements, especially in atmospheric science. Most major programming languages have an interface for NetCDF I/O, but the files here were written using the xarray Python package: https://xarray.pydata.org/en/stable/index.html. Therefore, if the user is working in Python, I recommend reading the files with xarray as follows (assuming xarray is installed in your path): import xarray as xr ds = xr.open_dataset('path-to-file') This will read the data in as an xarray 'Dataset', which is a container for multidimensional, labeled data: https://xarray.pydata.org/en/stable/data-structures.html ## Data details ## Each borehole contains a single loop of single mode fiber optic cable that is used to sense strain signals. I have split each borehole into a 'downgoing' and an 'upgoing' section where the downgoing is the closest to the start of the cable and the upgoing the furthest (this is arbitrary). The microstrain data are represented in the Dataset as two DataArrays named "down_data" and "up_data", respectively, where the 'values' attribute is a 2-dimensional numpy array of measurements. Each row corresponds to a single channel of data (i.e. a single point along the fiber) and each column corresponds to a single point in time. If you've read-in the data following the snippet above, you can plot them as follows: import matplotlib as plt ds["up_data"].plot() plt.show() ## Data processing ## The data are reported as microstrain relative to the start of recording at 2019-5-22T16:43:54 UTC. They have not been corrected for temperature but they have been realigned and 'gain-shift' corrected following the procedures outlined in the manuscript supplements. ################### ### SIMFIP data ### ################### The SIMFIP data are provided as a simple text file (comma separated) containing the datetime of each measurement, followed by the X (East), Y (North), and Z (vertical) components of the instrument. Units are microns. ########################## ### Potentiometer data ### ########################## The potentiometer data are provided as a NetCDF file, very similar to those provided for the DSS data. The correct units are described within the file but are microns. Note that, as with the DSS positive values signifies extension of the potentiometer element. ## Contact ## If you need any other information about these data, please contact me (Chet Hopp) and I'd be happy to help: chopp@lbl.gov