The most destructive explosion on earth in the past 10,000 years was the eruption of an obscure volcano in Indonesia called MountTambora. More than 13,000 feet high, Tambora blew up in 1815 and blasted 12 cubic miles of gases, dust and rock into the atmosphere and onto the island of Sumbawa and the surrounding area. Rivers of incandescent ash poured down the mountain’s flanks and burned grasslands and forests. The ground shook, sending tsunamis racing across the JavaSea. An estimated 10,000 of the island’s inhabitants died instantly.
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It’s the eruption’s far-flung consequences, however, that have most intrigued scholars and scientists. They have studied how debris from the volcano shrouded and chilled parts of the planet for many months, contributing to crop failure and famine in North America and epidemics in Europe. Climate experts believe that Tambora was partly responsible for the unseasonable chill that afflicted much of the Northern Hemisphere in 1816, known as the “year without a summer.” Tamboran gloom may have even played a part in the creation of one of the 19th century’s most enduring fictional characters, Dr. Frankenstein’s monster.
The eruption of Tambora was ten times more powerful than that of Krakatau, which is 900 miles away. But Krakatau is more widely known, partly because it erupted in 1883, after the invention of the telegraph, which spread the news quickly. Word of Tambora traveled no faster than a sailing ship, limiting its notoriety. In my 40 years of geological work I had never heard of Tambora until a couple of years ago when I started researching a book on enormous natural disasters.
The more I learned about the eruption of Tambora, the more intrigued I became, convinced that few events in history show more dramatically how earth, its atmosphere and its inhabitants are interdependent—an important matter given concerns such as global warming and destruction of the atmosphere’s protective ozone layer. So when the chance arose to visit the volcano while on a trip last fall to Bali and other Spice Islands, I took it.
Indonesia’s Directorate of Volcanology and Geologic Hazard Mitigation said that I should not attempt to climb Tambora—too dangerous. As my guide would later tell me, the name of the mountain means “gone” in a local language, as in people who have vanished on its slopes. But researchers who have studied the volcano encouraged me. “Is it worth it?” I asked Steve Carey, a volcanologist at the University of Rhode Island, who has made the climb. “Oh, my!” he said. That was all I needed to hear.
Through a travel agent in Bima, a city on Sumbawa, a friend and I hired a guide, a translator, a driver, a driver’s mate, a cook and six porters. We filled a van and traveled for hours, weaving among horse-drawn carriages (known locally as Ben-Hurs, after the chariots in the movie) as we headed for Tambora’s southern slope. The parched terrain was like savanna, covered with tall grasses and only a few trees. A few hours west of Bima, the huge bulk of Tambora begins to dominate the horizon. Formerly a cone or double-cone, it’s now shaped like a turtle’s shell: the eruption reduced the mountain’s height by more than 4,000 feet.
We camped a third of the way up the mountain, and set out at dawn for the summit, wending around boulders the size of small cars that were tossed like pebbles from the erupting volcano nearly two centuries ago. Our guide, Rahim, chose a trail that switched back and forth for about four miles. The day was warm and humid, the temperature in the 70s. Grasses in places were charred black, burned by hunters in pursuit of deer.
I was excited to approach the site of one of the most important geological events since human beings first walked the planet. Yet as I looked up at the mountain, I realized I had another purpose in mind. The climb was a chance to reassure myself that after treatment for two kinds of cancer in the past decade, I could still master such a challenge. For me, then, it was a test. For the two porters, striding along in flip-flops, it was a pleasant stroll in the country.
In repose for thousands of years, the volcano began rumbling in early April of 1815. Soldiers hundreds of miles away on Java, thinking they heard cannon fire, went looking for a battle. Then, on April 10, came the volcano’s terrible finale: three columns of fire shot from the mountain, and a plume of smoke and gas reached 25 miles into the atmosphere. Fire-generated winds uprooted trees. Pyroclastic flows, or incandescent ash, poured down the slopes at more than 100 miles an hour, destroying everything in their paths and boiling and hissing into the sea 25 miles away. Huge floating rafts of pumice trapped ships at harbor.
Throughout the region, ash rained down for weeks. Houses hundreds of miles from the mountain collapsed under the debris. Sources of fresh water, always scarce, became contaminated. Crops and forests died. All told, it was the deadliest eruption in history, killing an estimated 90,000 people on Sumbawa and neighboring Lombok, most of them by starvation. The major eruptions ended in mid-July, but Tambora’s ejecta would have profound, enduring effects. Great quantities of sulfurous gas from the volcano mixed with water vapor in the air. Propelled by stratospheric winds, a haze of sulfuric acid aerosol, ash and dust circled the earth and blocked sunlight.