Seismic events in the mine are not unusual, but on social media several Kiruna residents describe serious shaking in the bedrock.

"Feeled in Tuolla and it hasn't happened before," writes a signature.

Another writes that it was "felt in New Kiruna" and even residents of Lombolo testify to a strong tremor.

The area was secured before operation

Mine manager Joel Kangas announces that no one was injured.

- The mine was kept closed while the area was secured and that the mine reopened at 06:30, he says in a press release.

The magnitude measured 2.2

The local magnitude reached 2.2 on LKAB.'s own scale.

- In order to get answers to exactly where the seismic events take place, a scale is needed that is adapted to the conditions.

The Richter scale is designed to measure natural earthquakes at great distances, it measures at a different frequency and is too inaccurate for the smaller tremors that occur during mining, the company writes on its website.