Mexico qualifies as highly active. The country sits at the boundary of three pieces of the Earth's crust that fit together like a jigsaw puzzle -- called tectonic plates. Today's quake originated on a fault within the Cocos plate, which is on Mexico's western edge. "Whether or not faults rupture depends on the kind of stress that builds up," Bellini says. The Cocos plate scoots rapidly under the continental crust of the North American plate, which "builds up the stress and strain at a faster rate," Bellini says. "So you're liable to have more frequent earthquakes because of that." Mexico City is especially prone to severe damage because of the ground it sits on -- an ancient lakebed that quivers like jello, Bellini says. When earthquake waves pass through it, it jiggles, magnifying the vibrations. "So the reason that Mexico City seems susceptible to more damage is because of this amplification effect of the lake bed," Bellini says.
His conclusion? "This is probably the first AAA game that actually works on the Vive."
"North Korea's fourth test — in the context of repeated statements by U.S., Chinese, and South Korean leaders — throws down the gauntlet to the international community to go beyond paper resolutions and find a way to impose real costs on North Korea for pursuing this course of action," says Scott Snyder, a Korea expert at the Council on Foreign Relations. According to the NY Times, the test is bound to figure in the American presidential campaign, where several candidates have already cited the North's nuclear experimentation as evidence of American weakness — though they have not prescribed alternative strategies for choking off the program. The United States did not develop its first thermonuclear weapons — commonly known as hydrogen bombs — until 1952, seven years after the first and only use of nuclear weapons in wartime.
"When we see these fault systems producing multiple magnitude 4s, we start to get concerned that it could knock into higher magnitudes," says Daniel McNamara, author of a paper published online that a large earthquake near the storage hub "could seriously damage storage tanks and pipelines." "Given the number of magnitude 4s here, it's a high concern."