A magnitude 7.9 quake struck the Denali fault in 2002.

In the next few years there are three more 7+ magnitude quakes in the region.

He added: "A magnitude 8 quake is a rare event.

A magnitude 7.2 quake hit the trench itself in November 2004.

A magnitude 5 quake causes 10 times more ground motion.

In 1933, a magnitude 8.1 quake in the area killed more than 3,000 people.

Today a 5.4 magnitude quake rocked the northeastern region but caused no damage.

A magnitude 5.6 quake struck in southern Nevada 175 miles away.

Further earthquakes have been linked with the operation, including a 3.9 magnitude quake in 2004.

During the magnitude 6.3 quake on the 22nd of February the school suffered extensive damage and had to close.