Survivors of Indonesia’s Deadly Earthquake Face Threat of Volcano Eruption

GWEN IFILL:

Now, a closer look at the deadly earthquake in Indonesia. First, what caused the quake that struck the island of Java on Saturday? And is there a connection with the increased activity at the nearby Mount Merapi volcano?

To help us understand what's going on, I'm joined by Ken Hudnut, a geophysicist in the Pasadena office of the U.S. Geological Survey.

Welcome, Mr. Hudnut.

The area of the Pacific that we're talking about is commonly loosely known as the Ring of Fire. Can you describe what that means and why it's called that?

KEN HUDNUT, U.S. Geological Survey:

Well, in general, where plates are coming together — in this case, the Australian plate is coming underneath the Sunda plate along the Sunda Arc, and so there's an association of earthquakes and volcanic activity where those plates are coming together.

GWEN IFILL:

When we last heard of natural disasters happening in this region of the world, it was the 2004 tsunami. Help our viewers understand where this is in relation to that and whether there is any connection at all?

KEN HUDNUT:

There is certainly a connection. The same plate boundary, but farther to the northwest, ruptured in a magnitude 9.2 earthquake in December of 2004. That ruptured from the northern tip of Sumatra towards the north, up through the Andaman and Nicobar Islands.

In March of 2005, there was a magnitude 8.7 earthquake that ruptured off Sumatra, along the Mentawai Islands between Simuelue and Nias Islands.

This activity, this earthquake, and the eruptions of Mount Merapi are down on the island of Java, which is quite far to the southeast and actually east of Jakarta by about 250 miles.