An official of the National Center for Earthquake and Volcanoes, a subsidiary of the Saudi Geological Survey, said the tremors were light and there was no reason to worry. "Although the tremors are very light, people in these places feel them because their epicenter is not very deep,” said center director Hani Zahran on Friday.

The official said the four tremors were recorded between 2.22 a.m. and 12.20 p.m. on Friday.

The region between Harrat Khaibar and Harrat Al-Ithnain recorded two tremors of magnitude 3.25 and 3.3 two weeks ago. Another tremor measuring 3.9 on the Richter scale was registered in Harrat Al-Shaqah mid-April.

Zahran added that the occurrence of tremors of this magnitude in long intervals was quite normal. He urged residents in the area not to worry.

He added that those areas were earthquake zones, where dozens of tremors were being recorded daily but not felt by residents.