Earthquakes, which cannot be predicted or studied in the field, are highly vulnerable natural disasters and their consequences last for decades. They usually occur along active faults in orogenic belts, typically at depth. A typical active faults have a well defined geometry, characterized by a fault core zone enclosed by damage zone on both sides. The fault core zone contains the principle slip zone(PSZ), which is characterized by intense mechanical fracturing and often has different mineralogy than the wall rock, known as fault gouge. Experimental studies that have been done to replicate the fault gouge conditions, found that frictional characteristics of the fault gouge rock and the change in the friction from the wall to the core zone of the fault largely dictates the kinematics of the fault slip. Thus, it is important to understand the frictional evolution of the fault gouges.
There are several studies available across the globe on the major faults which measures the frictional properties of the faults. However, although being one of the most seismically active orogenic belts in the world, Himalayan Orogenic belts, there are no available studies that has measured frictional properties of the Himalayan fault gouges.
As a part of my first objective, I have completed the microstructural and compositional analysis of the fault gouges of the NW Himalayan Faults. Observations from the analysis matched with general observations in a fault gouges of the fault away from the fault core towards the wall rock.
Soon after, I developed friciton experimental protocol to conduct friction for to investigate friction of the NW Hmalayan faults. I conducted intial set of velocity stepping tests at different constant confining pressure (25, 50, 100, 150)MPa by varying displacement rate (0.1 - 1-10)um/s. initial results show that friction decreases with increasing confining pressure. I also observed mineralogical control on the gouge friction.
I also estimated velocity dependant friction rate parameter(a-b) which shows velocity strenghening (a-b>0) at all confining pressure.
I will be doing wet gouge experiments at different confinement pressure.