1938: The eruption of Bilyukai, on the Kamchatka peninsula in eastern Siberia, produced huge amounts of lava. Rivers of it, which, as it flowed away from the volcano, cooled and formed a crust on its surface.
The volcanologists V.F. Popkov and I.Z. Ivanov, showing scant regard for their personal safety, decided that the only way to properly study the lava was to go out on to it.
They tossed rocks on to the crust to strengthen it, and then Popkov gingerly stepped on to the band of lava that separated the riverbank from the crust. “Without letting go of Ivanov’s hand, I put . . . one asbestos-shod foot on the incandescent lava,” he wrote. “I released Ivanov’s hand and made another step by resting my body on the iron rod which I used as a walking stick and which sank slowly into the plastic mass.”