An earthquake measuring 3.2 on the Richter scale was felt in Fair Isle on Friday afternoon.
The epicentre was nine kilometres to the south-west of the island, according to the British Geological Survey.
Fair Isle resident and weather man Dave Wheeler said: “I heard a rumbling getting louder and louder like a big tractor driving up outside, and I felt some vibration. I went outside to look but there was nothing happening. Then I could hear the noise dying away.”
The rumbling lasted for less than 10 seconds, he said, and the slight tremors for less than a minute. Although the quake, which happened at 3pm, was small by world standards, it was one of the larger ones to be experienced in Shetland recently.
According to the British Geological Survey there are small quakes every few days in the UK, most of which are not noticed. The last one felt in Shetland was in January 2009.