Question

In Chile, the deepest earthquake occurred at 61.7°W longitude at a depth of 540 km. If the rocks at the focus began subducting 10 million years ago and are now 1000 km from their original position, what is the average rate of subduction in cm/yr?

Answer 1

The correct answer is - 1 cm/yr.

Alongside the western coast of South America, the Nazca plate and the South American plate are in a collision for several million years now, with the Nazca plate being the one that is subducting in this convergent plate boundary.

If the Nazca plate's focus has moved 1,000 km in the last 10 million years, than in order to get to the annual movement of the subduction we need to convert the km into cm first:

1 km = 10,000 cm

1,000 x 10,000 = 10,000,000

1,000 km = 10,000,000 cm

Than we need to divide the number of cm with the number of years:

10,000,000 / 10,000,000 = 1

And we get the result of 1 cm/yr.