Volcanoes can cause many different problems. Lava, ash and debris flows are the most common and serious volcanic hazards but severe eruptions can disrupt the climate for long periods or cause atmospheric shock waves. Eruptions can also cause tsunamis, volcanic earthquakes or the release of suffocating gases into the air. These hazards pose serious threats to both life and property. When a volcano comes to life, a few weeks may not be enough time to avert a tragedy.
Planning is the to saving people.
Well before the warning signs occur, people must be educated about volcanic hazards. Evacuation plans must be in place. Communication between scientists, officals, and media, and the general public should be outlined and practiced. Emergency measures must be thought out and agreed upon. The mudflow occurred after the eruption and 21,000 people where killed.