These are scary times, and for those citizens living in earthquake country, the times are not just scary, they are terrifying. For starters, a major earthquake is overdue along the Hayward Fault, in the East Bay area near San Francisco: It could happen at any moment. San Francisco has 120,000 buildings, at least 90% of them erected before the adoption of modern building codes in the 1970s. Most won’t flat-out collapse in a city-centered earthquake the size of 1989’s Loma Prieta, but there will be damage beyond repair from the quake and ensuing fire to about a quarter of the
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.