New evidence has shown that some faults that should not slip are weaker than scientists thought. Studies have shown that faults that dip less than 45 degrees should not slip because it is easier to form a new fault than to slip. New studies have shown that these faults do slip and they may act more like weak faults. The fabric in the rocks that are in the faults had too much friction for the faults to slide easily. Scientists tested the material found in the fault to find something close to what it occurs naturally. They did this by taking the rocks in the fault and grinding it into a powder substance, which is then tested in a machine that applies shear forces to the powder, and it measures the amount of force it would take to move the sides of the fault. The movements show that low angle faults contain too much friction to move, however they do move. The scientists conducted another study from a fault in Elba where they took the powder and produced frictional forces to prevent slipping. They made small squares from the rock an dfound that material that was prepared in this way were weak and sheared in one direction, which resulted in low friction, and this was because it contained clays that allowed the material to slide. This causes the faults to move a little, which could cause small earthquakes.
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