A Holocene history of collapse
Mount Popa is a large stratovolcano, rising 1,518 meters above the surrounding Myingyan Plain. Its main cone consists of overlapping layers of basalt and basaltic andesite lava flows, along with pyroclastic deposits from more explosive phases of its history. The volcano's growth began less than one million years ago, building upon an older lava plateau. Radiocarbon dating of paleosols layered between ash deposits shows that Popa was active in the early Holocene, producing several mild, Vulcanian-type explosive eruptions between 12,700 and 8,500 years ago.
The most dramatic recent event in Mount Popa's geological history occurred approximately 8,000 years ago. A massive portion of the volcano's flank became unstable and collapsed. This gravitational edifice collapse resulted in a debris avalanche of approximately 1.3 cubic kilometers of rock and soil, which traveled 11 kilometers from the summit. The event left a massive, horseshoe-shaped crater, breached to the northwest, that measures 1.6 kilometers wide. Immediately following the collapse, a magmatic eruption produced a pyroclastic flow of basaltic andesite, depositing 0.1 cubic kilometers of material. Geologists consider Mount Popa a dormant but potentially active volcano, given its Holocene-era activity.