TY - JOUR
T1 - Gouge stability controlled by temperature elevation and obsidian addition in basaltic faults and implications for moonquakes
AU - Cao, Shutian
AU - Zhang, Fengshou
AU - An, Mengke
AU - Elsworth, Derek
AU - He, Manchao
AU - Liu, Hai
AU - Zhao, Luanxiao
N1 - Publisher Copyright:
© 2024
PY - 2024
Y1 - 2024
N2 - Basalt is a major component of the earth and moon crust. Mineral composition and temperature influence frictional instability and thus the potential for seismicity on basaltic faults. We performed velocity-stepping shear experiments on basalt gouges at a confining pressure of 100 MPa, temperatures in the range of 100–400 °C and with varied obsidian mass fractions of 0–100% under wet/dry conditions to investigate the frictional strength and stability of basaltic faults. We observe a transition from velocity-neutral to velocity-weakening behaviors with increasing obsidian content. The frictional stability response of the mixed obsidian/basalt gouges is characterized by a transition from velocity-strengthening to velocity-weakening at 200 °C and another transition to velocity-strengthening at temperatures >300 °C. Conversely, frictional strengths of the obsidian-bearing gouges are insensitive to temperature and wet/dry conditions. These results suggest that obsidian content dominates the potential seismic response of basaltic faults with the effect of temperature controlling the range of seismogenic depths. Thus, shallow moonquakes tend to occur in the lower lunar crust due to the corresponding anticipated higher glass content and a projected temperature range conducive to velocity-weakening behavior. These observations contribute to a better understanding of the nucleation mechanism of shallow seismicity in basaltic faults.
AB - Basalt is a major component of the earth and moon crust. Mineral composition and temperature influence frictional instability and thus the potential for seismicity on basaltic faults. We performed velocity-stepping shear experiments on basalt gouges at a confining pressure of 100 MPa, temperatures in the range of 100–400 °C and with varied obsidian mass fractions of 0–100% under wet/dry conditions to investigate the frictional strength and stability of basaltic faults. We observe a transition from velocity-neutral to velocity-weakening behaviors with increasing obsidian content. The frictional stability response of the mixed obsidian/basalt gouges is characterized by a transition from velocity-strengthening to velocity-weakening at 200 °C and another transition to velocity-strengthening at temperatures >300 °C. Conversely, frictional strengths of the obsidian-bearing gouges are insensitive to temperature and wet/dry conditions. These results suggest that obsidian content dominates the potential seismic response of basaltic faults with the effect of temperature controlling the range of seismogenic depths. Thus, shallow moonquakes tend to occur in the lower lunar crust due to the corresponding anticipated higher glass content and a projected temperature range conducive to velocity-weakening behavior. These observations contribute to a better understanding of the nucleation mechanism of shallow seismicity in basaltic faults.
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U2 - 10.1016/j.ijmst.2024.04.012
DO - 10.1016/j.ijmst.2024.04.012
M3 - Review article
AN - SCOPUS:85195452018
SN - 2095-2686
JO - International Journal of Mining Science and Technology
JF - International Journal of Mining Science and Technology
ER -