Lappajärvi is a lake in Finland, in the municipalities of Lappajärvi, Alajärvi and Vimpeli. It is formed in a 23 km wide, partly eroded meteorite impact crater. The lake is part of Ähtävänjoki basin together with Lake Evijärvi that is located downstream of it.
The Lappajärvi impact structure is estimated to be 77.85 ± 0.78 million years old. Experts working on Finland's Olkiluoto nuclear waste repository project have studied Lake Lappajärvi to help them project how Finnish landscapes might look one million years in the future and beyond.An island in the middle of the lake, Kärnänsaari, gives the name to the black impact melt rock found there, locally called kärnäite.The towns on the shore are Lappajärvi and Vimpeli. Although not very near any, the nearest major city is Seinäjoki.
Address 62600, Finland
Coordinates 63°8'52.593" N 23°40'14.904" E