Assertion: volcano's crater | /r/MadeOf | six active vents
Facets:
value: during visits by open univ scientists
type: TEMPORAL
Source sentences:
text: Crater 1 contained six active vents during visits by Open Univ scientists.
text: Crater 2 had been completely filled by tephra, but included two active vents characterized by synchronous noisy explosions.
text: Crater 1 contained three active vents (figure 2).