Assertion: volcano's lava lake | /r/HasProperty | made since last recorded observation
Facets:
Source sentences:
text: The visit . . . on 10-11 November 1992 showed that since the last recorded observation, made using Landsat TM data from 9 February 1987, the lava lake in the N crater had disappeared (presumably frozen over and collapsed), but that the lava lake in the S crater . . . was still active.