This README.txt file was updated on 21/09/2023 by N. Harrichhausen

GENERAL INFORMATION

1. Title of Dataset: Holocene earthquake rupture of the XEOLXELEKElk Lake fault in the Greater Victoria area, British Columbia, Canada. Dryad, Dataset.
2. Author Information A. Principal Investigator Contact Information Name: Nicolas Harrichhausen Institution: ISTerre, Universit Grenoble Alpes
   Address: Grenoble, France Email: n.harrichhausen@univ-grenoble-alpes.fr; nharrichhausen@gmail.com
3. Date of data collection (06/2021 - 10/2021)
4. Geographic location of data collection: Saanich, British Columbia, Canada
5. Information about funding sources that supported the collection of the data: This research was supported by National Science Foundation Earth Sciences (NSF EAR) grants #1756943 and #2046278 to Dr. Morell, NSF EAR grant #1756834 to Dr. Regalla, funding from the USGS National Cooperative Geologic Mapping Program to Dr. Bennett, an NSERC Discovery grant #2017-04029 and Canada Research Chair to Dr. Nissen, an NSERC Alexander Graham Bell Canada Graduate scholarship to T. Finley, an NSERC Post Graduate Scholarship (PGGSD - 504197 - 2017) and Centre National d'tudes Spatiale (CNES) postdoctoral fellowship to N. Harrichhausen, and a University of Victoria Jamie Cassels Undergraduate Research Award to E. McLeod.

SHARING/ACCESS INFORMATION

1. Licenses/restrictions placed on the data: Data under copyright of: Harrichhausen, et al., (2023). Holocene earthquake rupture of the XEOLXELEKElk Lake fault in the Greater Victoria area, Canada
2. Links to publications or works that cite or use the data:

• Harrichhausen, N., Finley, T., Morell, K. D., Regalla, C, Bennett, S.E.K., Leonard, L.J., Nissen, E., McLeod, E., Lynch, E. M., Salomon, G., Sethanant, I., (2023). Paleoseismic study of the XEOLXELEK-Elk Lake fault: A newly identified Holocene fault in the northern Cascadia forearc near Victoria, British Columbia, Canada. Proceedings of the 11th International INQUA Meeting on Paleoseismology, Active Tectonics and Archeoseismology.
• Harrichhausen, N., Finley, T., Morell, K. D., Regalla, C., Bennett, S.E.K., Leonard, L.J., Nissen, E., McLeod, E., Lynch, E. M., Salomon, G., Sethanant, G. (Submitted to JGR: Solid Earth). Discovery of an active forearc fault in an urban region: Holocene rupture on the XEOLXELEKElk Lake fault, Victoria, British Columbia, Canada

1. Recommended citation for this dataset: Harrichhausen, N., Finley, T., Morell, K. D., Regalla, C., Bennett, S.E.K., Leonard, L.J., Nissen, E., McLeod, E., Lynch, E. M., Salomon, G., Sethanant, G. (2023). Holocene earthquake rupture of the XEOLXELEKElk Lake fault in the Greater Victoria area, British Columbia, Canada. Dryad, Dataset.

DATA & FILE OVERVIEW

1. File List (with descriptions):

Harrichhausen_et_al_AugerHoles.docx: Basic sediment descriptions of sediment encountered in auger holes with depths in centimeters.

Harrichhausen_et_al_trench_structure.xlsx: Bedding and fault plane measurements in degrees.

Harrichhausen_et_al_unit_descriptions.xlsx: Detailed unit descriptions of units shown in trench logs (Fig. 5; Fig. S2, Harrichhausen et al., (JGR Solid Earth)).

Harrichhausen_et_al_ERT_3m_Apr22_2021.stg
Harrichhausen_et_al_XELF_ERT_3m_west_terrain.txt
Harrichhausen_et_al_ERT_1m_Apr22_2021.stg
Harrichhausen_et_al_XELF_ERT_1m_west_terrain.txt
Harrichhausen_et_al_Waterski_Beach_ERT_3m_Oct21_2022.stg
Harrichhausen_et_al_Waterski_ERT_terrain.txt

.stg files: resistivity data collected using the AGI Ministing.

Following 3 lines of header information, the next set of lines (marked RESIST) contain the data collected during contact resistance testing, prior to the electrical resistivity tomography (ERT) survey. For these data, the format is as follows: Record number, RESIST, date, time, V/I, error in tenths of percent, output current in mA, address of the first electrode used for the test, address of the second electrode, gain range for the receiver, high voltage output for the current transmitter, measurement time, number of measurement cycles.

The remaining lines (marked DIP-DIP) contain the data collected during the dipole-dipole ERT survey, with the following data format: Record number, DIP-DIP, date, time, V/I, error in tenths of percent, output current in mA, apparent resistivity in Ohm-m, dipole size a (m), distance between dipoles na (m), X-coordinate (m) for the midpoint between the two dipoles, gain range for the receiver, high voltage output for the current transmitter, measurement time, number of measurement cycles.
Note: the calendar dates are incorrect in these files the true dates are in the filenames.

terrain.txt files: relative distance and elevation data collected using a total station.
Following 3 lines of header information, the first column is horizontal distance (m) along the profile, and the second column is relative elevation (m).

README.md

METHODOLOGICAL INFORMATION

1. Description of methods used for collection/generation of data:

The structural data and unit descriptions were collected during the excavation of a ~31 m-long, 1-2 m-wide, <3 m-deep paleoseismic trench perpendicularly across the the scarp of the XEOLXELEKElk Lake fault (XELF) on the eastern shore of XEOLXELEK (Elk Lake) in August 2021. Structural measurements were taken using a Brunton compass were compiled and analyzed using the programs Stereonet 10.1.6, available at https://www.rickallmendinger.net/. Detailed sedimentary descriptions were made for each geologic unit portrayed in the trench logs shown in the supporting information of the manuscript.

The auger data was collected from up to 3.4 m-deep auger holes from the floor of, and alongside the trench.

The electrical resistivity data were collected April 22, 2021 at Eagle Beach and October 21, 2021 at Waterski Beach. The resistivity files (.stg) are correlated with levelling data that are also provided (.txt). We used an Advanced Geosciences Inc. (AGI) MiniSting R1 resistivity meter with a 28-electrode cable in dipole-dipole electrode configuration. At Eagle Beach, data were collected along a profile co-located with the eventual western wall of the trench and extending beyond the trench footprint to the northeast and southwest. First, an 81 m-long profile was surveyed, centered on the topographic scarp, with an electrode spacing of 3 m and resolvable depth of ~16 m. This was followed by a 27 m-long profile nested within the longer line, with an electrode spacing of 1 m, to collect higher-resolution data of the shallow subsurface (to ~5.5 m depth). At Waterski Beach, we used the same methodology to conduct a 3-m spaced survey along an 80 m long profile centered on a slight ~60 cm high elevation rise coinciding with the along strike extension of the XELF east of XEOLXELEK. The survey was conducted at an angle of 63 relative to the fault scarp as a result of the nearby lakeshore. For all surveys, levelling data at each electrode position were surveyed with a Spectra Precision Focus 6 5 Total Station.

1. Methods for processing the data:

Bedding and foliation planes were plotted and analyzed using Stereonet 10.1.6 software (Allmendinger et al., 2011; Cardozo & Allmendinger, 2013).

Resistivity data were processed using AGIs EarthImager 2D software, the apparent resistivity data were inverted using a damped least-squares method, for 5 iterations, to produce resistivity models of the subsurface that minimized the root-mean-square misfit between the model-predicted and measured values.

1. Instrument- or software-specific information needed to interpret the data:

Stereonet 10.1.6 used for structural analyses. Publicly available at https://www.rickallmendinger.net/

Advanced Geosciences Inc. EarthImager 2D software used for resistivity data processing is available at https://www.agiusa.com/agi-earthimager-2d.

1. Standards and calibration information, if appropriate:

N/A

1. People involved with sample collection, processing, analysis and/or submission:

Harrichhausen, N., Finley, T., Morell, K. D., Regalla, C.A., Bennett, S.E.K., Leonard, L.J., Nissen., E., McLeod, E., Lynch, E. M., Salomon, G., Sethanant, G. all assisted in data collection.

DATA-SPECIFIC INFORMATION: Information on variables are provided in excel spreadsheets.

REFERENCES:

Allmendinger, R. W., Cardozo, N., & Fisher, D. M. (2011). Structural geology algorithms: Vectors and tensors. Cambridge University Press.

Cardozo, N., & Allmendinger, R. W. (2013). Spherical projections with OSXStereonet. Computers & Geosciences , 51 , P. 193205