Frictional properties of anorthite (feldspar): implications for the lower boundary of the seismogenic zone

Earth, Planets and Space

Table 1 Experimental conditions and results of experiments on anorthite gouge (average grain size 1 µm)

Run ID	Dry/wet^a	T (°C)	Coefficient of friction, μ	Error^b μ	a − b	Error^b a − b	Load cell^c data used
FD020	Dry	20	0.6970	0.0034	0.00092	0.00012	I
FD200	Dry	200	0.6863	0.0011	0.00233	0.00006	O
FD375	Dry	375	0.6842	0.0004	0.00299	0.00003	I
FD500	Dry	500	0.6760	0.0021	− 0.00320	0.00009	O
FD600	Dry	600	0.6415	0.0115	− 0.00044	0.00066	I
FW200	Wet	200	0.7071	0.0012	− 0.00037	0.00016	O
FW400	Wet	400	0.7483	0.0019	− 0.01587	0.00022	O

^aIn the dry experiments, Ar gas was used to apply a confining pressure of 150 MPa; in the wet experiments, a confining pressure of 200 MPa was applied, and the pore-water pressure was 50 MPa
^bErrors on µ before the step change in sliding velocity and on (a − b) are reported as the curve-fitting error
^cDifferential stress in the gouge layer was measured by the internal load cell (I), but if no internal load cell data were available, corrected external load cell data (O) were used. See Masuda et al. (2019) for details