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No two volcanic eruptions happen in exactly the same way. Volcanoes are inherently unpredictable. Even so, scientists have learned to read the many signs volcanoes give off prior to an eruption in the hope of minimizing damage to lives and personal property. This video segment adapted from NOVA describes the race to read the signs presented by Mount Pinatubo in the Philippines, just before it unleashed one of the most powerful eruptions of the 20th century.