Kaali Meteorite Crater

Kaali Meteorite Crater is located 80 kilometers from the largest city in Saaremaa island – Kuressaare.

It is one of Estonia’s most unique geological objects.

Early explorers considered the ring-shaped Kaali crater as a volcanic depressions or karst hole formed by the dissolution of limestone, gypsum or salt. Actually,  about 4000 years ago a meteorite crashed at Kaali, creating 9 craters ranging from 5 meters diameter up to 50 meters.

The meteor cluster had an impact velocity of 10-20 km/s and a mass of 20-80 tons. At the altitude of 5-10 km the meteor broke into pieces. The largest fragment produced the main crater with a depth of 22 m.

The energy of the impact is comparable with the Hiroshima Nuclear bomb. The meteorite impact burned forests within a radius of 6 km.

The meteo arrangement of the lake basin origin was first proposed by J. kalkun-Kaljuvee in 1922. In 1937 Ivan Reinvald collected 30 fragments of meteoritic iron from the collateral craters. The analysis of the documents showed that the cosmic body fell to the Kaali area belonged to the most common type of iron meteorite, coarse octahedrite, with the contents of Fe and Ni totaling 91.5 and 8.3%, respectively.

The structure of the craters and the distribution of meteoritic material indicate that the meteorite fell from the east-northeast at an angle of 45 degrees. The original mass of the meteorite could be from 400 to 10 000 tonnes of mass effect was 20 to 80 tonnes, initial speed upon entering the atmosphere is 15 to 45 kilometers per second speed at impact ranged from 10 to 20 kilometers per second.

The atmosphere through the meteorite is heated and broke into pieces at an altitude of five to ten kilometers, covered the earth like a meteorite shower. As a result, the main crater, 110 meters in diameter and 22 meters depth, and at least eight security craters with a diameter of 12 to 40 meters and a depth of one to four metes were formed.

The craters or their slopes do not contain marine sediments. Therefore, the craters may not be older than the time the field came from the sea. The explosion scattered in the air clearly fine particles of soil and rock that formed by melting glassy spherules. These spherules have been found in marshes and lakes sedimets near the craters. The age of the layers of peat with microimpactites is 7500 to 7600 year, which is the most likely age of the Kaali craters.
In the main crater there is a natural water known as Lake Kaali. Its diameter ranging from 30 to 60 meters depending on the water. The depth is one to six meters. The lake is fed by groundwater and precipitation. The lower layers of sediment are about six meters thick and up to 4 000 years old.