once (I can’t move until my neighbor does…), giving an implosion. The biggest, deepest earthquakes happen where temperatures and pressures are so high that we don’t think rocks can break. Humans have never made a hole anywhere nearly as deep as the deeper earthquakes. We have mostly quit testing atomic bombs. And, abig earthquake is way bigger than a big atomic bomb. Penn State students, being naturally even-tempered, don’t kick hard enough to actually explode Pepsi machines. And Penn State basements are not deep enough to account for the deeper earthquakes.Points Earned:1/1Correct Answer:AYour Response:A13.Volcanic eruptions cause many hazards to humans, and many geologists are employed to study these hazards and warn people. For a single, large, explosive volcanic eruption such as Mt. St. Helens, which ofthe following is not a worry that these volcanic-hazards geologists would warn people about?A.Pyroclastics, including bus-sized pieces that could fall on people’s heads and kill them.B.Tsunamis, or giant waves, that could drown people, if the volcano is in the ocean or a very large lake and the eruption moves a lot of water out of the way. C.Mudflows and landslides that could bury people and buildings.D.Climatic warming, with the volcano causing a sudden heat wave that would harm people living in big cities.E.Poisonous gases, that could kill people who breathe them in.This is one of those interesting cases where “slow” and “fast” are different. Volcanoes release carbon dioxide, and carbon dioxide warms. But carbon dioxide stays up a long time, and no single volcanic eruption puts up enough carbon dioxide to make a detectable difference to the concentration in the air and the temperature of the Earth. However, a single big eruption can put enough material into the stratosphere to block enough
sunlight to cool the Earth by a degree or two for a year or two. So the climatic hazard from a single big volcanic eruption is cooling, not warming. Explosive volcanoes are often large and steep, and may have huge glaciers. As heat melts the ice, and as melted rock moving into the volcano bulges the sides, huge landslides and mudflows happen. Tens of thousands of people have been killed in single mudflows. Well over 100,000 people live on the deposit from one old mudflow from Mt. Rainier (and those who know about that Osceola Flow really hope it doesn’t happen again!). A tsunami is a big wave, caused by an earthquake, landslide, meteorite impact,or volcanic eruption that displaces sea water. Waves can be 100 feet high or more, and do incredible damage.