Mount Rainier, one of the most dangerous volcanoes in the U.S. and in the world, is widely expected to erupt again. The only unknown facing scientists is when the massive stratovolcano, 4,392 meters tall and located 87 kilometers southeast of Seattle in Washington state, will finally explode. Scientists from the United States and Norway recently mapped the electric and magnetic signatures of magma flows beneath Mount Rainier (pronounced “ray-near”). They’ve also discovered a mammoth magma reservoir below the mountain that will fuel any eruption with massive magma flows. The research found out that magma or fluid molten rock is trapped...