Stimulus stimulate the sodium ion voltage gated channel to open in the axon. This allow many Na ion to enter the axon and causes depolarisation as the pd in the axon getting less negative charge (from -70mV to -50mV).
Reverse faults are exactly the opposite of normal faults. If the hanging wall rises relative to the footwall you have a reverse fault. Reverse faults occur in areas undergoing compression. If you imagine undoing the motion of a reverse fault, you will undo the compression and thus lengthen the horizontal distance between two points on either side of the fault.
if you stood on the fault plane the block on the right would be under your feet. this is thus the footwall. The tan sandstone has been pushed up and over itself. This offset of the hanging wall indicates that this is a reverse fault.
