The United States hasn't suffered a catastrophic earthquake in more than a century, and that long historical gap may be lulling people into a false sense of security, the National Academies, the nation's leading scientific advisory body, warned in a report published today.

While the study was largely completed before the devastating earthquake and tsunami that ripped through northeast Japan earlier this month, that disaster serves as a reminder that severe earthquakes can pose calamitous risks even for nations most prepared for their strikes, the academies said.

"A sense has developed that the [United States] can cope effectively with the earthquake threat and is, in fact, 'resilient,'" the report says. "However, coping with moderate events may not be a true indicator of preparedness for a great one."

The Japan earthquake, for example, registered a 9.0 on seismologists' magnitude scale. The last time an earthquake greater than 8.0 magnitude -- what's defined as a "great" earthquake -- struck the United States was 1964, when a 9.2-magnitude quake hit Alaska. Given Alaska's sparse population, few lives were lost, and the country has to go back to 1906 in San Francisco for its last devastating shock.

The report, prepared by the academies' research arm, the National Research Council, lays out a 20-year plan for increasing U.S. resilience to earthquakes, including the risk of severe strikes against major population centers like Los Angeles. The report endorses the 2008 strategic plan set out by the National Earthquake Hazards Reduction Program (NEHRP), a multi-agency effort led by the National Institute of Standards and Technology.

NEHRP requires more funding to achieve its goals, the council noted. The program received $129.7 million funding in 2009, but will require $306 million annually for five years to begin implementing its road map. An effort will also be needed to diffuse NEHRP's findings to communities most at risk of earthquake strikes, the report says.

The tasks recommended by the report include: deploying the remaining 75 percent of the Advanced National Seismic System, which provides rapid magnitude and location alerts for quakes; completing national and urban seismic hazard maps to identify at-risk areas; and modeling the expect and improvised emergency responses to a quake, in order to improve pre-disaster preparedness.

Click here to see the report.