Seismic Waves is a newsletter published by the National Earthquake Hazards Reduction Program. "Magnitude is popularly used as a shorthand measure of earthquake size and severity. Usually, though, when people assess 'how bad' a quake was, they consider not only the size of the earthquake and how hard the ground shook, but also its effects on people and the built environment. Magnitude alone is not a reliable indicator of such impacts. In 2002, a magnitude 7.9 earthquake struck a sparsely populated region in the southern interior of Alaska, causing no deaths and little damage to structures.1 The magnitude 7.9 quake that struck China's densely populated Sichuan province in May 2008, however, killed more than 69,000 people. As these examples illustrate, the impact of an earthquake depends on how many people are exposed to it. Also important is how well protected these people are from the quake. Have most of the buildings where they live and work been built to resist earthquake damage, or are many of them relatively vulnerable to ground shaking?"
National Earthquake Hazards Reduction Program: http://www.nehrp.gov/
Seismic Waves (July 2008)