The best background to read for this video is in the book Volcano Cowboys.
The short version: this is volcanologist David Johnston (and an equally crazy coworker) walking in the heart of a pre-eruption Mount St. Helens on April 30, 1980, for samples. They really needed the samples, but this was something beyond dangerous to do.
The volcano allowed it to happen on that day . . .
38 years ago, #USGS scientist David Johnston hikes into Mount St. Helens’ crater to sample the summit pond. Shaky video from his colleague on the rim recently unearthed in USGS-CVO archives. https://t.co/1GyXb0xjCn pic.twitter.com/6EP9zRMcVP
— USGS Volcanoes🌋 (@USGSVolcanoes) April 27, 2018
. . . and then on May 18th killed Dr. Johnston, who was manning a USGS observation point about five miles from the crater, in a direct line with the lateral blast, as well as over fifty other people. Until that day, volcanologists didn’t know that volcanoes can erupt sideways so violently.
It was a costly lesson, but the death toll would have been much higher if Johnston and his colleagues hadn’t issued and maintained a very controversial no-go order for vicinities near what everyone called “America’s Mount Fuji” until it erupted.
Caption: Source, CC BY-SA 3.0.