Just over two weeks ago, a large earthquake struck Nepal, killing more than 8,000 people, and literally moving mountains. This morning, the earth moved again, the shaking reaching a substantial magnitude of 7.3 on the Richter scale.

Today's quake was larger than the many aftershocks that have rattled the region since the April 25 quake (also known as the Ghorka quake), and it was centered in a different place. The earthquake a few weeks ago started about 50 miles northwest of Nepal's capital, Kathmandu.

Today's epicenter was about 50 miles northeast, almost exactly between Kathmandu and Mount Everest:

An epicenter is the location on the earth's surface directly above the place where the earthquake started. The spot underground where the earthquake started is called the focus, which in this case was about 9.3 miles underground--a relatively shallow depth for earthquakes.