What is the root or history of the word earthquake?

Question

How the word earthquake was formed?
Where does it comes from?

Answer 1

earthquake ...
c.1280, as eorthequakynge, from earth + quake. O.E. had eorðdin in this sense.

Answer 2

The word "quake" just means "to shake." Earth, in addition to being the name of our planet, also refers to the ground below us. So if the ground is shaking, "earthquake" is a literal description of the event. Similar events on other bodies, though they have never been directly observed, are often referred to in like fashion, such as "moonquakes," which don't occur because the Moon is not geologically active.