DOI: 10.5061/dryad.cvdncjt9p
title: Data from: Brittle sedimentary strata focus a multimodal depth distribution of seismicity during hydraulic fracturing in the Sichuan basin, southwest China

description: The number of background earthquakes (ML ≥ 0) in the southern Sichuan
 basin, southwest China, has increased thirtyfold as a result of hydraulic
 fracturing. Background events are originally deep (4-6 km) within the
 sedimentary section but build into a multimodal distribution both at depth
 and in the shallow stimulated reservoir (2-4 km) - representing a
 counterpoint to the usual triggering of seismicity on deep sub-reservoir
 basement faults. Surprisingly, the largest events (ML ≥ 3) evolve in the
 deep sedimentary strata (4-6 km) that are hydraulically isolated from the
 injection zone (2-4 km) by low permeability layers. We evaluate the
 friction-stability rheology of the strata within the full stratigraphic
 section to define the feasibility of nucleation within these shallow and
 deep strata. These show velocity-neutral to velocity-weakening behavior in
 the shallow reservoir transitioning to more strongly velocity-weakening
 with increase in both depth and temperature. Poroelastic stress
 calculations confirms that stress transfer, rather than transmitted fluid
 pressures, are capable of directly reactivating critically-stressed faults
 at depth, with fluid pressures the triggering source within the shallow
 reservoir.
description: # Brittle sedimentary strata focus a multimodal depth distribution of
 seismicity during hydraulic fracturing in the Sichuan basin, southwest
 China **Mengke An, Derek
 Elsworth, Fengshou Zhang, Rui Huang, Junlun Li, Zhengyu Xu, Zhen Zhong,
 and Manchao He. Brittle Sedimentary Strata Focus a Multimodal Depth
 Distribution of Seismicity during Hydraulic Fracturing in the Sichuan
 Basin, Southwest China. *Tectonophysics*.** **Data S1** **The
 friction-displacement data for the nine shear experiments on rock gouges
 from Xixiangchi to Doushantuo Formations in Sichuan Basin.** **Authors**
 Mengke An Department of Civil and Environmental Engineering, The Hong Kong
 Polytechnic University, Hung Hom, Kowloon, Hong Kong 100872, China.
 Department of Energy and Mineral Engineering, EMS Energy Institute and G3
 Center, The Pennsylvania State University, University Park, PA 16802, USA.
 &lt;2015mengkean@tongji.edu.cn&gt; Derek Elsworth Department of Energy and
 Mineral Engineering, EMS Energy Institute and G3 Center, The Pennsylvania
 State University, University Park, PA 16802, USA. Department of
 Geosciences, The Pennsylvania State University, University Park, PA 16802,
 USA.   Fengshou Zhang Department of Geotechnical
 Engineering, College of Civil Engineering, Tongji University, Shanghai
 200092, China.   Rui Huang Department
 of Geotechnical Engineering, College of Civil Engineering, Tongji
 University, Shanghai 200092, China. &lt;2110412@tongji.edu.cn&gt;   Junlun
 Li Laboratory of Seismology and Physics of Earth’s Interior, School of
 Earth and Space Sciences, University of Science and Technology of China,
 Hefei 230026, China.   Zhengyu Xu PetroChina
 Hangzhou Institute of Geology, Hangzhou 310023, China.
   Zhen Zhong School of Civil
 Engineering, Shaoxing University, Shaoxing 312000, China.
   Manchao He State Key Laboratory for
 Geomechanics and Deep Underground Engineering, China University of Mining
 and Technology, Beijing, Ch [17854@tongji.edu.cn](mailto:17854@tongji.e)
 **File lists (files found within DataS1.zip)** An_et_al_2024_SICH_1.xlsx
 An_et_al_2024_SICH_2.xlsx An_et_al_2024_SICH_3.xlsx
 An_et_al_2024_SICH_4.xlsx An_et_al_2024_SICH_5.xlsx
 An_et_al_2024_SICH_6.xlsx An_et_al_2024_SICH_7.xlsx
 An_et_al_2024_SICH_8.xlsx An_et_al_2024_SICH_9.xlsx **File description**
 An_et_al_2024_SICH_1.xlsx – The shear displacement (column 1) and
 coefficient of friction (column 2) data for Experiment SICH-1.
 An_et_al_2024_SICH_2.xlsx – The shear displacement (column 1) and
 coefficient of friction (column 2) data for Experiment SICH-2.
 An_et_al_2024_SICH_3.xlsx – The shear displacement (column 1) and
 coefficient of friction (column 2) data for Experiment SICH-3.
 An_et_al_2024_SICH_4.xlsx – The shear displacement (column 1) and
 coefficient of friction (column 2) data for Experiment SICH-4.
 An_et_al_2024_SICH_5.xlsx – The shear displacement (column 1) and
 coefficient of friction (column 2) data for Experiment SICH-5.
 An_et_al_2024_SICH_6.xlsx – The shear displacement (column 1) and
 coefficient of friction (column 2) data for Experiment SICH-6.
 An_et_al_2024_SICH_7.xlsx – The shear displacement (column 1) and
 coefficient of friction (column 2) data for Experiment SICH-7.
 An_et_al_2024_SICH_8.xlsx – The shear displacement (column 1) and
 coefficient of friction (column 2) data for Experiment SICH-8.
 An_et_al_2024_SICH_9.xlsx – The shear displacement (column 1) and
 coefficient of friction (column 2) data for Experiment SICH-9.