Finnish impact structures

11 impact structures (or craters) have been found in Finland so far. Impact structures are form when an asteroid or a comet collide with the planet Earth with cosmic speed (11-70 km/s). Kinetic energy of the projectile transform into pressure- or shockwave in fraction of second. In the impact point the target rock and the projectile will vaporize, melt and brecciate. Impact will produce a crater, which is 20-30 times larger that the impacted projectile.

 

Finnish impact structures
Suomen törmäyskraatterit
  1. Lappajärvi
  2. Sääksjärvi
  3. Söderfjärden
  4. Iso-Naakkima
  5. Lumparn
  6. Suvasvesi N
  7. Karikkoselkä
  8. Saarijärvi
  9. Paasselkä
  10. Suvasvesi S
  11. Keurusselkä

Numbers in list above are same as in the map on left. Numbers represent the order in which these impact structures are confirmed. An impact structure east from Finnish border is Jänisjärvi in Russia. 

 
Structure name      Diam. km                Age Ma             Lat.     Long.
 
Lappajärvi          17    (17-23)            73.3 ±5.4         63°09'N  23°42'E
Sääksjärvi           5                      543   ±12          61°24'N  22°24'E
Söderfjärden         5.5  (5-6)            ~560   (540)        63°00'N  21°35'E
Iso-Naakkima         3    (2-3)           ~1200   (900-1200)   62°11'N  27°11'E
Lumparn              9    (7-10)          ~1000   (500-1200)   60°08'N  20°07'E
Suvasvesi N          3.5  (1.5-5?)         ~240/~780 ±10       62°41'N  28°11'E
Karikkoselkä         1.3  (1.3-2.4?)       ~250   (250-450)    62°13'N  25°14'E
Saarijärvi           2.1  (1.4-2.1 )        600-1980           65°17'N  28°25'E
Paasselkä           10    (9-12.5 )       <1885                62°12'N  29°23'E
Suvasvesi S          3.8  (3.5-4?)         ~240/~780 ±10 ?     62°35'N  28°14'E
Keurusselkä         11.5  (12-20?)        <1880   (>1000?)     62°08'N  24°37'E