A February map from the U.S Geological Survey shows the estimated range of the great Cascadia earthquake of 1700.
Biggest threat zones
The biggest threats of a U.S. mega-quake (generally defined as one of magnitude 7.0 or greater) lie along three fault lines:
The Cascadia subduction zone stretches from northern Vancouver Island through Seattle and Portland, Ore., to Northern California, separating the Juan de Fuca and North America plates. Giant quakes are believed to occur there every 300 to 600 years; the last was Jan. 26, 1700. Recent research suggests the region could have a 37 percent chance of a magnitude-8.2 quake or greater in the next 50 years.
The San Andreas transform fault runs the length of California, separating the Pacific and North American plates. The last mega-quake was in 1906 near San Francisco, but large earthquakes of magnitude 6.0 or above are relatively common in historical terms, having occurred as recently as September 2004 near Parkfield.
The New Madrid seismic zone stretches southwest from New Madrid, Mo. (pronounced MAD-rid), and is most active in Arkansas, Illinois, Indiana, Kentucky, Mississippi, Missouri and Tennessee, where it regularly produces small- to medium-intensity temblors. Three magnitude-8.0 quakes are believed to have occurred in the region from December 1811 to February 1812; had Memphis, Tenn., existed at the time, it likely would have been destroyed. Since then, the largest earthquake was a magnitude-6.6 quake in October 1895 near Charleston, Mo.
msnbc.com research/M. Alex Johnson. Sources: NASA Astrophysics Data System, National Oceanic and Atmospheric Administration, Oregon State University College of Oceanic and Atmospheric Sciences, Scripps Institution of Oceanography, U.S. Geological Survey
A massive earthquake like the one that unleashed a giant tsunami and killed nearly 16,000 people in Japan a year ago not only could happen here in the U.S., but probably will — and relatively soon in terms of seismological history.
The Tohoku earthquake was the most closely monitored in history, yielding an unprecedented breadth of data, geophysicists and seismologists say. And for residents of the Pacific Northwest, the new data should be worrisome.
"It's just like Japan, only a mirror image," said Gerard Fryer, a geophysicist at the University of Hawaii and the Pacific Tsunami Warning Center.
Biggest threat zones
The biggest threats of a U.S. mega-quake (generally defined as one of magnitude 7.0 or greater) lie along three fault lines:
The Cascadia subduction zone stretches from northern Vancouver Island through Seattle and Portland, Ore., to Northern California, separating the Juan de Fuca and North America plates. Giant quakes are believed to occur there every 300 to 600 years; the last was Jan. 26, 1700. Recent research suggests the region could have a 37 percent chance of a magnitude-8.2 quake or greater in the next 50 years.
The San Andreas transform fault runs the length of California, separating the Pacific and North American plates. The last mega-quake was in 1906 near San Francisco, but large earthquakes of magnitude 6.0 or above are relatively common in historical terms, having occurred as recently as September 2004 near Parkfield.
The New Madrid seismic zone stretches southwest from New Madrid, Mo. (pronounced MAD-rid), and is most active in Arkansas, Illinois, Indiana, Kentucky, Mississippi, Missouri and Tennessee, where it regularly produces small- to medium-intensity temblors. Three magnitude-8.0 quakes are believed to have occurred in the region from December 1811 to February 1812; had Memphis, Tenn., existed at the time, it likely would have been destroyed. Since then, the largest earthquake was a magnitude-6.6 quake in October 1895 near Charleston, Mo.
msnbc.com research/M. Alex Johnson. Sources: NASA Astrophysics Data System, National Oceanic and Atmospheric Administration, Oregon State University College of Oceanic and Atmospheric Sciences, Scripps Institution of Oceanography, U.S. Geological Survey
A massive earthquake like the one that unleashed a giant tsunami and killed nearly 16,000 people in Japan a year ago not only could happen here in the U.S., but probably will — and relatively soon in terms of seismological history.
The Tohoku earthquake was the most closely monitored in history, yielding an unprecedented breadth of data, geophysicists and seismologists say. And for residents of the Pacific Northwest, the new data should be worrisome.
"It's just like Japan, only a mirror image," said Gerard Fryer, a geophysicist at the University of Hawaii and the Pacific Tsunami Warning Center.
No comments:
Post a Comment