Helsinki University’s Institute of Seismology on Monday confirmed that a 1.6-magnitude earthquake struck in South Ostrobothnia late on Sunday evening.
The earthquake was shallow, according to the institute's seismologists.
"It was perhaps at a depth of about five kilometres," said institute director Timo Tiira.
Local residents in Alajärvi took to social media on Sunday evening to report loud booms that caused windows to shake around 11pm. People in Alajärvi, Lappajärvi, Soini and Vimpeli also reported rumbling sounds.
The region has experienced a few shallow earthquakes over the past decades, according to Tiira, who noted that a 3.8-magnitude earthquake hit Alajärvi in 1979.
"Sunday's quake was very near the site of the one in 1979--probably not more than a kilomtre off," he said.