Occurrence of Attributes in Original Text

The text related to the cultural heritage 'Surtsey' has mentioned 'Above sea level' in the following places:
Occurrence Sentence Text Source
[2] The most recent survey (2007) shows the island's maximum elevation at 155xc2xa0m (509xc2xa0ft) above sea level.
It is estimated that Surtsey will remain above sea level for another 100 years.[when?]
The total volume of lava emitted during the three-and-a-half-year eruption was about one cubic kilometre (0.24xc2xa0cuxc2xa0mi), and the island's highest point was 174 metres (571 feet) above sea level at that time.