A Cumbrian school has been closed after monitoring equipment detected vibrations in a five-storey building.
Specialist measuring equipment was installed at the 1,500-pupil West Lakes Academy in Egremont last year when similar tremors were felt.
It was thought the vibrations then may have been sparked by shifting geology caused by Cumbria's heavy rainfall.
The latest alert is believed to be linked to drilling during building work at the academy site.
Investigations are ongoing and school bosses hope to reopen the site on Monday.
No-one has been hurt and there have been no reports of structural damage.
But school bosses said they were taking no chances with safety.
Mick Farley, deputy chairman of governors at the academy, which opened in 2008, said: "The monitoring equipment went off last night and as a precaution it was decided that the academy would be closed to students.
"We believe it was caused by some drilling associated with a new build nearby, but we will check that out during the course of the day.
"The intention is that if everything checks out we reopen again fully on Monday."