An American Tsunami?

Magma fuels??a string of volcanoes in the Cascade Range, including Mount St. Helens

Sources: Brian Atwater, U.S. Geological Survey; Kenji Satake, AIST, Geological Survey of Japan; Vasily Titov, National Oceanic and Atmospheric Administration; Natural Resources Canada; LandScan/UT-Battelle

SOUNDING THE ALARM For residents of the Pacific Northwest coast, the jolt of an earthquake would be the first signal that they should head for higher ground People too far away to feel the quake would be alerted by sirens or broadcast warnings, thanks to??a 26-nation network of seismic, tidal and sea-level monitors

Warning system The workhorses of the Deep-ocean Assessment and Reporting of Tsunamis are a series of buoys tethered to the ocean floor and linked to the outside world by satellite. The Pacific is tsunami ready, but not the Atlantic or Indian oceans

Bottom-pressure recorder Can detect minute changes in water pressure caused by a passing tsunami as small as 0.4 in. (1 cm)

Computer Sends signal to buoy

Communications buoy Receives data from ocean floor along with readings from surface weather instruments, and relays to a satellite

IT HAPPENED BEFORE Geological and historical evidence points to a giant Cascadia earthquake that sent a tsunami across the Pacific in January 1700

Hour 1 Waves strike North America Hour 5 Tsunami front passes Hawaii Hour 10 First waves reach Japan Hur 15 Philippines, New Zealand hit Hour 20 Tsunami spans Pacific ocean