Originally Posted by
A0283
Volcanic Cloud Height : Best estimate of ash-cloud top is around 16454 FT (5142 M) above sea level, may be higher than what can be observed clearly. Source of height data: ground observer.
Spurious precision, surely! It looks as if the ground observer estimated "around 2000m above the summit", then added the height of the summit, making the precise-looking height of 5142m which was then converted to feet inaccurately (5142m is 16870ft). Similarly with the earlier notice quoted in post #15.