Of these volcanic zones, the Central Volcanic Zone of which Lascar is a member of is the largest, covering parts of Peru, Bolivia, Argentina and Chile. The Central Volcanic Zone is located between two areas where subduction is shallower and volcanic activity is absent. In the Central Volcanic Zone, volcanism has been active for 120 million years, although it has undergone eastward migration during this time. Water released from the subducting plate triggers the formation of basaltic magmas that are then injected into the crust.