Colombia was once associated with cocaine trafficking and powerful drug lords, but today's reality is different: It's stable, a magnet for foreign investment and diplomatically engaged — and this weekend hosts the Summit of the Americas. Increasingly, Colombia is seen as South America's rising star.

Scientists who watch for earthquakes have discovered a big increase in the number of small quakes in the middle of the country. It's an area that's usually pretty quiet geologically.

The scientists suspect the quakes are caused by wastewater wells. They plan to discuss their findings later this month at a seismology conference, but they've shared the basics with NPR.

Bill Ellsworth, a seismologist at the U.S. Geological Survey, says new technology over the past decade has given scientists a much better feel for when the Earth shakes.

Mitt Romney was on the attack Wednesday, using a specific statistic to back up his claim that women, especially, have suffered economically under President Obama.

"Over 92 percent of the jobs lost under this president were lost by women," Romney said on Fox News. "His policies have been really a war on women."

The Romney campaign claims that 92.3 percent of those who have lost jobs during the Obama administration are women. It's a claim the campaign has made in speeches, on Twitter and on the Romney website.

George Zimmerman has been charged with second-degree murder in the shooting of Florida teen Trayvon Martin. Audie Cornish speaks with former federal prosecutor Brett Meltzer about the legal aspects of the case going forward.

The phenomenon that is TEDMED has rolled into the nation's capital. And I'm camped out at the Kennedy Center for the nerdfest.

What's the big deal? I'm still trying to figure that out as the meeting is well into its second day. It's an event, that's for sure, and it's supposed to be a way for people who care a lot about health care to get together and make some headway on thorny problems.

Two U.S. Marines have been killed and two others injured when the V-22 Osprey they were in crashed Wednesday during a training exercise in Morocco.

NPR's Larry Abramson is reporting that the reservists were part of a Marine unit participating in the annual African Lion exercise with the Moroccan military. The two severely injured Marines are being treated in country.

More information about those killed and wounded will be released after the notification of next of kin.

The cause of the crash is still being investigated, but NPR's Abramson notes:

A retirement crisis is looming. As people live longer, one study finds that half of all households are at risk of coming up short on retirement money. And while many working households may feel they simply don't have enough to spare for retirement, experts say some of the biggest barriers to saving up are psychological.