This file was prepared 20200820 by Chun-Yu Ke (ck659@cornell.edu) This file supplements data associated with the publication: "The Earthquake Arrest Zone" Geophysical Journal International Authors: Chun-Yu Ke (ck659@cornell.edu), Gregory C. McLaskey (gcm8@cornell.edu) and David S. Kammer (dkammer@ethz.ch) Alternate contact: Bill S. Wu (sw842@cornell.edu) -------------------------- Dataset Description: These data are from Laboratory Earthquake Experiments from the Cornell 3 m apparatus in support of the following research: Loading a 3-meter granite slab containing a saw-cut simulated fault, we generated slip events that spontaneously nucleate, propagate, and arrest before reaching the ends of the sample. These rupture events have a slip distribution that varies along the fault and make them more similar to natural earthquakes than standard stick-slip events that rupture the entire sample. We propose an analytical crack model that fits our measurements. Similar to natural earthquakes, laboratory measurements show coseismic slip that gradually tapers near the rupture tips. Measured stress changes show roughly constant stress drop in the center of the ruptured region, a maximum stress increase near the rupture tips, and a smooth transition in between, in a region we describe as the earthquake arrest zone. The proposed model generalizes the widely used elliptical crack model by adding gradually tapered slip at the ends of the rupture. Different from the cohesive zone described by fracture mechanics, we propose that the transition in stress changes and the corresponding linear taper observed in the earthquake arrest zone are the result of rupture termination conditions primarily controlled by the initial stress distribution. It is the heterogeneous initial stress distribution that controls the arrest of laboratory earthquakes, and the features of static stress changes. We also performed dynamic rupture simulations that confirm how arrest conditions can affect slip taper and static stress changes. If applicable to larger natural earthquakes, this distinction between an earthquake arrest zone (that depends on stress conditions) and a cohesive zone (that depends primarily on strength evolution) has important implications for how seismic observations of earthquake fracture energy should be interpreted. -------------------------- When utilizing this data, please cite as listed below, and provide reference to one or more of the following associated publications: Dataset: Ke, C.-Y., McLaskey, G. C., Kammer, D. S. (2020) Data from: The Earthquake Arrest Zone [dataset], Cornell University eCommons Repository. https://doi.org/10.7298/b3bm-6r17 Publications: Ke, C.-Y., McLaskey, G. C., Kammer, D. S. (2021) The Earthquake Arrest Zone, Geophysical Journal International, Volume 224, Issue 1, January 2021, Pages 581–589. https://doi.org/10.1093/gji/ggaa386 Wu, B. S., and McLaskey, G. C. (2019) Contained Laboratory Earthquakes Ranging from Slow to Fast, Journal of Geophysical Research: Solid Earth, 124. https://doi.org/10.1029/2019JB017865 Ke, C.-Y., McLaskey, G. C., Kammer, D. S. (2018) Rupture Termination in Laboratory-Generated Earthquakes. Geophysical Research Letters 45, 12784-12792. https://doi.org/10.1029/2018GL080492 -------------------------- This work was sponsored by USGS Earthquake hazards grant G18AP00010 and National Science Foundation grants EAR-1645163, EAR-1763499, and EAR-1847139 -------------------------- These data are shared under a Creative Commons Universal Public Domain Dedication (CC0 1.0); the data will be openly available for re-use, modification and distribution; proper attribution to the original data creators is expected. See citation information above. -------------------------- Software note: The MAT-File version is 7.3, and were generated with with MATLAB R2019a. File labelling: Experiments were conducted in runs which consist of series of events. We refer to the run generated after a large increase in normal stress as a Poisson expansion sequence, denoted “P” or “Poisson”. For catalog purposes a run called “FS01-40-10MPa-P-3” denotes the third Poisson expansion sequence at ~10 MPa normal stress in the 40th overall day of experiments on the first set of blocks used on the Cornell 3 m apparatus. Individual slip events are labeled by their number since the beginning of the slip sensor data file. The timing of the events are stored in and array ‘event-time’ described below, e.g., “FS01-40-10MPa-P-3-04” denotes the fourth event in the sequence “FS01-40-10MPa-P-3”. Experiment data: Each .mat file contains an array labeled ‘event_time’ and three MATLAB structures: ‘pressure’, ‘slip’, and ‘strain’. ‘pressure’ is a MATLAB structure with 2 fields: ‘time’ and ‘signal’. ‘pressure.time’ is a column vector describing the time stamp (seconds) of each row of data found in ‘signal’. All data were recorded at 50 kHz and then averaged down to 5 kHz, which is provided here. ‘pressure.signal’ is a 2-column matrix, storing data recorded from hydraulic pressure sensors in the array of normal loading cylinders (column 1) and shear loading cylinders (column 2). Data is in Volts where 5 V is 10,000 psi. The conversion from Voltage to sample average stress is 6.4 MPa/V for the normal stress (East-side cylinders) and 3.2 MPa/V for the shear stress (North-side cylinders). ‘slip’ is a MATLAB structure with 2 fields: ‘time’ and ‘signal’. ‘slip.time’ is a column vector describing the time stamp (seconds) of each data point found in ‘signal’. All data were recorded at 50 kHz and then averaged down to 5 kHz, which is provided here. ‘slip.signal’ is a 16-column matrix, storing data recorded from eddy current sensor channels E1 - E16, respectively. E1 is near the forcing end (North) and E16 is near the leading edge (South) of the sample. All data is in units of Volts and the conversion factor is 128 microns/V. ‘strain’ is a MATLAB structure with 2 fields: ‘time’ and ‘signal’. ‘strain.time’ is a column vector describing the time stamp (seconds) of each data point found in ‘signal’. All data were recorded at 1 MHz and then averaged down to 5 kHz, which is provided here. ‘strain.signal’ is a 16-column matrix, storing data recorded from 16 channels of semiconductor strain gage pairs (S1 - S16). S1 is near the forcing end (North) and S16 is near the leading edge (South) of the sample. The strain gage pairs are in a half-bridge configuration. All data are zeroed at the beginning of each experiment, where normal and shear loading were held at a negligible level since the end of the previous experiment. The excitation voltage is 12 V and the gage factor is 178. All data is in units of Volts and the conversion factor from Volts to strain is 22.84 /V assuming the Young's modulus is 30 GPa and the Poisson's ratio is 0.23. ‘event_time’ is a column vector describing the time stamp (seconds) of each identified rupture event. The locations of the various sensors are listed below: Sensor X (m) Y (m) Z (m) Sensor X (m) Y (m) Z (m) E1 0.050 0.000 0.000 S1 0.150 0.005 0.000 E2 0.250 0.000 0.000 S2 0.350 0.005 0.000 E3 0.450 0.000 0.000 S3 0.550 0.005 0.000 E4 0.650 0.000 0.000 S4 0.750 0.005 0.000 E5 0.850 0.000 0.000 S5 0.950 0.005 0.000 E6 1.050 0.000 0.000 S6 1.150 0.005 0.000 E7 1.250 0.000 0.000 S7 1.350 0.005 0.000 E8 1.450 0.000 0.000 S8 1.550 0.005 0.000 E9 1.650 0.000 0.000 S9 1.750 0.005 0.000 E10 1.850 0.000 0.000 S10 1.950 0.005 0.000 E11 2.050 0.000 0.000 S11 2.050 0.005 0.000 E12 2.250 0.000 0.000 S12 2.150 0.005 0.000 E13 2.450 0.000 0.000 S13 2.350 0.005 0.000 E14 2.650 0.000 0.000 S14 2.550 0.005 0.000 E15 2.850 0.000 0.000 S15 2.750 0.005 0.000 E16 3.050 0.000 0.000 S16 2.950 0.005 0.000 Selected events used in this study: Completely contained events: FS01-038-7MPa-P-1-01 FS01-038-7MPa-P-1-02 FS01-038-7MPa-P-1-03 FS01-040-10MPa-P-1-02 FS01-040-10MPa-P-2-01 FS01-040-10MPa-P-3-01 FS01-040-10MPa-P-3-02 FS01-040-4MPa-RP-1-02 FS01-040-4MPa-RP-1-03 FS01-040-4MPa-RP-1-04 FS01-040-4MPa-RP-2-02 FS01-040-4MPa-RP-2-03 FS01-040-4MPa-RP-2-04 FS01-040-4MPa-RP-2-05 FS01-040-4MPa-RP-2-06 FS01-040-4MPa-RP-3-02 FS01-040-4MPa-RP-4-03 FS01-040-4MPa-RP-4-04 FS01-040-4MPa-RP-4-05 FS01-041-4MPa-RP-1-03 FS01-041-4MPa-RP-1-04 FS01-043-4MPa-P-1-02 FS01-043-4MPa-RP-1-03 FS01-043-4MPa-RP-1-04 Partially contained events: FS01-039-7MPa-P-1-01 FS01-039-7MPa-P-1-02 FS01-040-4MPa-RP-1-05 FS01-040-4MPa-RP-2-07 FS01-040-4MPa-RP-3-03 FS01-040-4MPa-RP-4-06 FS01-041-10MPa-P-1-02 FS01-041-4MPa-RP-1-06 FS01-042-4MPa-P-1-04 FS01-042-4MPa-P-1-05 FS01-043-10MPa-P-1-02 FS01-043-4MPa-RP-1-05 FS01-043-7MPa-P-1-01