Qualla: Mount Colo: The Volcano That Saved an Island

Mount Colo: The Volcano That Saved an Island: Introduction

Thu, 02 Apr 2026 00:00:00 GMT

For 85 years, the volcano slept. The 7,000 people living on Una-Una island in the Gulf of Tomini fished its surrounding waters, farmed its slopes, and paid little attention to the low, broad mountain at the island's center. Mount Colo rises only 507 meters above sea level, modest enough to seem harmless. Its two-kilometer-wide caldera, with a small cone growing inside it like a seed in a bowl, gave the only hint that this was a place where the earth could open. On July 23, 1983, it did.

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Mount Colo: The Volcano That Saved an Island: The First Warning

Thu, 02 Apr 2026 00:00:00 GMT

Mount Colo had erupted before. In 1898, a VEI 3 eruption sent lahars cascading down the mountain's flanks and triggered an explosion from the crater lake. The island was evacuated, property was destroyed, but the damage remained manageable and the inhabitants returned. For the ne...

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Mount Colo: The Volcano That Saved an Island: Ninety Percent Scorched

Thu, 02 Apr 2026 00:00:00 GMT

The eruption on July 23, 1983, was rated VEI 4, ten times more powerful than the 1898 event. Pyroclastic flows, superheated avalanches of gas, ash, and rock moving at devastating speed, swept over virtually the entire island. Volcanic ash rose nine miles into the sky and drifted ...

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Mount Colo: The Volcano That Saved an Island: Thirty Years of Absence

Thu, 02 Apr 2026 00:00:00 GMT

No one came back. The fear of the volcano kept Una-Una uninhabited for nearly three decades. The jungle slowly reclaimed the scorched slopes, and without human interference, something remarkable happened beneath the waves. The coral reefs surrounding the island, left undisturbed ...

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Mount Colo: The Volcano That Saved an Island: A Diver's Volcano

Thu, 02 Apr 2026 00:00:00 GMT

Today, Una-Una island sits within the Kepulauan Togean National Park, part of the Coral Triangle, the global epicenter of marine biodiversity. More than 30 dive sites ring the island, their reefs covered in massive sea fans and pristine coral formations. Reef sharks patrol the dr...

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Mount Colo: The Volcano That Saved an Island: The Caldera's Quiet

Thu, 02 Apr 2026 00:00:00 GMT

Mount Colo has produced only three recorded eruptions in its history. The long silences between them are part of what makes it dangerous, offering enough time for people to forget what the mountain can do. The caldera remains, a two-kilometer basin that holds its small cone like ...

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