The massive earthquake and tsunami in Japan overwhelmed even the most rigorous disaster plans — and raised fresh questions about preparations in the U.S. Disaster planners discuss the best ways to plan for the unthinkable, and whether most cities and towns are doing enough to prepare.

Speaking with us is Sheri Fink, a senior fellow with the New America Foundation. She studied medical care and hospital preparedness in large-scale emergencies. She won a Pulitzer Prize for her New York Times Magazine story profiling a New Orleans hospital in the days ...