On June 3rd, 1991, a catastrophic pyroclastic flow was triggered at Mount Unzen, Japan, following the collapse of a growing lava dome. This surge of superheated gas, volcanic ash, and debris rushed down the mountainside at immense speeds, extending up to 4.5 kilometers from its source. The devastating event resulted in the tragic loss of 43 lives, including those of volcanologists and journalists who were documenting the volcano’s activity. Footage captured of the pyroclastic flow as it surges down the mountain has become some of the most iconic footage of a volcano ever recorded. Its ubiquitous presence in almost every volcano documentary underscores its extrodinary status.
Today, we unveil footage documenting a pyroclastic flow of extraordinary scale and intensity from Mount Merapi (captured in March 2023). It is one of the most incredible pyroclastic flows ever caught on camera.
The footage captured is the result of a partial lava dome collapse which is a common precursor to pyroclastic flows at Mount Merapi. These domes form from viscous lava accumulating at the volcano’s summit. When structural instability within the dome occurs, a portion or the entirety of the dome may collapse. This rapid disintegration releases superheated gas, ash, and rock fragments, generating a pyroclastic flow – a fast-moving, ground-hugging surge capable of traveling several kilometers at devastating speeds.
Mount Merapi, located in Central Java, Indonesia, is one of the world’s most active and dangerous stratovolcanoes. Renowned for its frequent eruptions, Merapi’s geological behavior is typified by the growth of unstable lava domes, pyroclastic flows, and lahars (volcanic mudflows).
