<span>Before an eruption, scientists look for gases and changes in the volcanoes shape, before an eruption the number and intensity of small earthquakes increases, this is caused by the movement of magma, prior to the eruption. Magma forms in the mantle and is a result of high temperature and low pressure.</span>
Answer:It causes random changes and the allele frequency of certain traits may increase or decrease.
Explanation:
Hope I am right
