How high is that lava fountain?
Detailed Description
Annotated image showing how lava fountain heights are measured using a trigonometric equation. Geologists measure two angles, from eye-level to the top and bottom of the lava fountain. These angles, and the distance between the geologist and the fountain, are used in a trigonometric equation to determine heights of the top and bottom portions of the fountain. The two values are added together to get the total lava fountain height. USGS photo of fissure 22 taken during the 2018 Kīlauea lower East Rift Zone eruption on May 20, by L. DeSmither.
Sources/Usage
Public Domain.