For today's Geo Quiz were headed south of the 38th parallel. A South Korean city with a 24-hour listening post is on our radar screen.

It's the 5th largest city in South Korea. And it's 100 miles south of Seoul.

It takes less than an hour to get there from Seoul ... that's if you ride the high-speed rail known as the KTX or Korea Train Express. South Korea's Earthquake Research Center is located in this city.

Scientists there have now set up high-tech sensors to detect certain sound and seismic waves. they're monitoring for a possible North Korean underground nuclear test.

South Korean officials say the North has atomic test facilities ready to go.

So what's the name of this city that serves as the capital of South Province?