[1] With the advent of high-velocity shear apparatus, several experimental studies have been performed in recent years, improving our understanding of the evolution of fault strength during seismic slip. However, these experiments were conducted under relatively low normal stress (<20 MPa) and using small cylindrical samples where a large gradient in slip velocity exists across the sliding surface. Given the above limitations, the extrapolation of these experimental results to natural conditions is not trivial. Here we present results from an experimental study on gabbroic rocks using a newly developed rotary shear apparatus capable of reaching higher normal stress (up to 50 MPa) on ring-shaped samples (30/50 mm internal/external diameter) and allowing precise control of the imposed slip velocity function. The results confirm that steady state shear stress during the melt-lubricated phase of the experiment depends on normal stress in the form of a power law equation as predicted by theoretical models. However, the exponent appears closer to 0.5, contrary to the theoretical prediction of 0.25. We observe no systematic dependence of shear stress on acceleration, but increasing deceleration drastically decreases the recovery of friction during final slip. We find that the slip-weakening distance decreases inversely with increasing normal stress, in agreement with theoretical considerations, and decreases with increasing slip rate. Extrapolation of the slip-weakening distance to natural conditions predicts a slip velocity for ancient seismic events of 0.3-1 m/s when compared with field estimates. These values compare well with seismological estimates.

Despite considerable effort over the past several decades, the mechanics of earthquake rupture remains largely unknown. Moderate-to large-magnitude earthquakes nucleate at 7-15 km depth and most information is retrieved from seismology, but information related to the physico-chemical processes active during rupture propagation is below the resolution of this method. An alternative approach includes the investigation of exhumed faults, such as those described here from the Adamello Massif (Italian Alps), and the use of rock deformation apparatus capable of reproducing earthquake deformation conditions in the laboratory. The analysis of field and microstructural/mineralogical/geochemical data retrieved from the large glacier-polished exposures of the Adamello (Gole Larghe Fault) provides information on earthquake source parameters, including the coseismic slip, the rupture directivity and velocity, the dynamic friction and earthquake energy budgets. Some of this information (e.g., the evolution of the friction coefficient with slip) can be tested in the laboratory with the recently installed Slow to HIgh Velocity Apparatus (SHIVA). SHIVA uses two brushless engines (max power 280 kW) and an air actuator in a rotary shear configuration (nominally infinite displacement) to slide solid or hollow rock cylinders (40/50 mm int/ext diameter) at: (1) slip rates ranging from 10 lm s -1 up to 9 m s -1; (2) accelerations up to 80 m s -2 ; and (3) normal stresses up to

One moderate- to large-magnitude earthquake (M > 6) nucleates in Earth's crust every three days n average, but the geological record of ancient fault slip at meters-per-second seismic velocities (as opposed to subseismic slow-slip creep) remains debated because of the lack of established fault-zone evidence of seismic slip. Here we show that the irreversible temperature-dependent transformation of carbonaceous material (CM, a constituent of many fault gouges) into graphite is a reliable tracer of seismic fault slip. We sheared CM-bearing fault rocks in the laboratory at just above subseismic and at seismic velocities under both water-rich and water-deficient conditions and modeled the temperature evolution with slip. By means of micro-Raman spectroscopy and focused-ion beam transmission electron microscopy, we detected graphite grains similar to those found in the principal slip zone of the A.D. 2008 Wenchuan (Mw 7.9) earthquake (southeast Tibet) only in experiments conducted at seismic velocities. The experimental evidence presented here suggests that high-temperature pulses associated with seismic slip induce graphitization of CM. Importantly, the occurrence of graphitized fault-zone CM may allow us to ascertain the seismogenic potential of faults in areas worldwide with incomplete historical earthquake catalogues

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Of all the socio-economic changes caused by the Covid-19 pandemic, the disruption to workforce organizations will probably leave the largest indelible mark. The way work will be organized in the future will be closely linked to the experience of working under the same institution’s response to the pandemic. This paper aims to fill the gap in knowledge about smart working (SW) in public organizations, with a focus on the experience of the employees of two Italian research organizations, CNR and INGV. Analysing primary data, it explored and assessed how SW had been experienced following the implementation of governmental measures aimed at limiting the spread of COVID-19.