Image Courtesy of university of california, berkeley Shock Waves Harmless shock waves known as primary waves (yellow circle) come seconds before slower, destructive secondary waves (red circle). Related Links: Video of ShakeAlert in Action Detailed ShakeAlert Proposal An early warning system that predicts an earthquake's approaching shock wave up to a minute before it strikes is ready to become operational throughout California. Further, a recently proposed bill would fund expansion of the system.The bill, introduced by state Sen. Alex Padilla (D), would support the ShakeAlert system, developed by the U.S. Geological Survey and an international coalition of universities. It is
Arch dams, classically curved monoliths situated in narrow valleys, are not as common as other types of dams, such as embankment dams and gravity dams. ENR takes a look at some of the biggest arch dams in the world, both completed and under construction.