In the following years , cavers widened the sides of the cave and discovered new branches , leading the total extension to . In 1973 , some glass slabs were set in particular spots in the cave , in order to verify the solidity of subterranean space . The slabs resisted to 1976 Friuli earthquake , showing Karst region was avoided the quake . Later , geologists and biologists achieved studies and researches on cave geomorphology and animal species living in the cavity
1976 Friuli earthquake
1976 Friuli earthquake
Grotta Regina del Carso