Photo: Courtesy of AP Images The magnitude-6.3 quake that hit Christchurch on the South Island of New Zealand on Feb. 22 caused more damage than the magnitude-7.1 quake in the same region in September because the more recent temblor was only five kilometers deep and only about 10 km from the city center. Damage to historic structures, especially Christchurch Cathedral, was significant; however, even modern buildings—including the Pyne Gould Guiness Building —collapsed, for a total of about 12. Soil liquefaction caused mudflows that damaged roads and houses. Reports say the quake is not connected to the same fault line as
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.