tremor
earth tremor
microseism

He's all set up to study earth tremors around here.

Earth tremors happen most of the time, although many are not felt.

There had been earth tremors but nothing to worry about.

If serious earth tremors begin, he said, the town will probably have to be evacuated.

A bad earth tremor rolled through here last week and a tree hit the phone lines down the street.

"I thought that was because of the earth tremors," Bart said.

"Marcus, do you often experience earth tremors here in the jungle?"

How had she known an earth tremor was coming?

Earth tremors began in February, becoming more frequent over the next two months.

As the man was preparing his order, an earth tremor struck the town and from outside came the sound of screaming.