Mechanical data from rotary shear experiments on material derived from outcrops felsic and mafic rocks in the East African Rift Zone

In all experiments, multiple series of velocity-steps were performed to obtain the velocity dependence of friction. The data can be modeled using rate-and-state friction equations (see Marone, 1998). We used the rate-and-state friction tool included in the XLOOK program to invert the data for all RSF parameters. For more details on the inversions scheme, see e.g. Reinen and Weeks, 1993. The excel-files included give the best fit values for the different parameters and different velocity steps. In some cases, one state variable was sufficient to get a satisfactory fit, in other cases two were needed. Note that steps that led to unstable stick-slips proved very difficult to model, since the sliding velocity tends to go to infinity (no damping included in the model). However, in most if not all cases, a result of the inversion could be found that was satisfactory, at least for the initial sliding after the step. Finally, in some cases a long term linear hardening or weakening trend was present, which was corrected. The data is provided in a folder with 14 subfolders for 14 experiments/samples. Detailed information about the files in these subfolders as well as information on how the data is processed is given in the explanatory file Hellebrekers_et_al_2019_Data_explanation.docx. Contact person is André Niemeijer - Projectleader - a.r.niemeijer@uu.nl