A biorhythm is a hypothetical cyclic pattern of alterations in physiology, emotion , and/or intellect.
Consider the name and what they are like and you will reach the conclusion that they are natural. "Natural" disasters.
Yes
Most natural disasters are completely natural. These include earthquakes, volcanic eruptions, floods, severe storms, tornadoes, cyclones (including typhoons and hurricanes), hailstorms, droughts,...
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