Staying safe

Pyroclastic flows can move faster than 100 km per hour at more than 400 °C, so the only safe plan is to leave before they start.

During an earthquake: Drop, Cover, and Hold On

Earthquakes strike without warning, and most injuries come from things falling or flying, not from the ground itself. The action that USGS and the Great ShakeOut drills recommend is Drop, Cover, and Hold On. If you are indoors, drop where you are onto your hands and knees, before the shaking knocks you down. Crawl under a sturdy desk or table for cover and hold on to it securely, ready to move with it. If there is no desk or table nearby, crawl next to an interior wall and protect your head and neck with your arms. Stay away from exterior walls, windows, hanging objects, mirrors, tall furniture, large appliances and kitchen cabinets full of heavy things or glass.

If you are outdoors, move to a clear, open area if you can, away from power lines, trees, signs, buildings and vehicles, anything that can fall on you. If you are driving, pull over to the side of the road and set the parking brake. A drill is a good time to look around your home or classroom for things that could fall and to secure or move them afterwards.

Tsunamis

A large earthquake under the sea can lift the water above it and start a tsunami. NOAA's National Weather Service warns that during a tsunami dangerous coastal flooding and powerful currents may continue for hours or days, and that the first wave may not be the last or the largest. Stay out of the hazard or evacuation zone until local officials say it is safe. If there is earthquake damage, avoid fallen power lines and stay away from buildings, bridges and piers, because heavy objects may fall from them during an aftershock. Keep listening to official radio, television or phone alerts, and keep phone calls short so the lines stay open for emergencies.

Near volcanoes

Volcanoes give more warning than earthquakes, because magma moving underground causes earthquakes, ground swelling and gas changes that observatories watch. The most dangerous hazard close to a volcano is the pyroclastic flow, a fast avalanche of hot ash, rock and gas. USGS says they typically move faster than 100 km per hour at more than 400 °C, and BGS gives temperatures of 100 to 600 °C. They are difficult or impossible to escape, so evacuation must happen before they occur. Lahars, mudflows of volcanic debris and water, can rush down river valleys far from the summit; USGS calls them the most threatening volcanic hazard in the Cascades. Ash fall can reach hundreds or thousands of kilometres away, and at Pinatubo jets flying through the ash cloud suffered about $100 million in damage.

Pinatubo also shows why warnings matter. Because scientists forecast the eruption and people were moved out of the danger zones in time, at least 5,000 lives were saved. Living near a volcano is a choice millions of people make for good reasons, fertile soil among them, and the safest way to do it is to know the local hazard map and evacuation routes and to leave early when officials say so.