The most powerful earthquake in 40 years struck deep beneath the Indian Ocean near the Indonesian island of Sumatra Sunday, triggering tsunamis that devastated villages and resorts, killing tens of thousands and leaving untold numbers missing.

A devastating earthquake struck under the Indian Ocean causing massive tidal waves that have so far killed over 24,000 and injured and displaced hundreds of thousands more. Gwen Ifill leads a discussion with two experts, one who focuses on the…