* * *
AROUND seven o’clock on the evening of April 10, Mount Tambora erupted once again, this time far more violently. Three columns of flaming lava shot into the air, meeting briefly at their peak in what one eyewitness termed “a troubled confused manner.” Almost immediately the entire mountain appeared to be consumed by liquid fire, a fountain of ash, water, and molten rock shooting in every direction. Pumice stones—some walnut-sized but others twice the size of a man’s fist—rained down upon the village of Sanggar, nineteen miles away. After an hour, so much ash and dust had been hurled into the atmosphere that darkness hid the fiery mountaintop from view.
As the ash clouds thickened, hot lava racing down the mountain slope heated the air above it to thousands of degrees. The air quickly rose, leaving behind a vacuum into which cooler air rushed from all directions. The resulting whirlwind tore up trees by the roots and swept up men, cattle, and horses. Virtually every house in Sanggar was flattened. The village of Tambora, closer to the volcano, vanished under a flood of pumice. Cascading lava slammed into the ocean, destroying all aquatic life in its path, and creating tsunamis nearly fifteen feet high which swept away everything within their reach. Violent explosions from the reaction of lava with cold seawater threw even greater quantities of ash into the atmosphere, and created vast fields of pumice stones along the shoreline. These fields, some of which were three miles wide, were light enough to float; they drifted out to sea where they were driven west by the prevailing winds and ocean currents. Like giant icebergs, the pumice fields remained a hazard to ships for years after the eruption. The British ship Fairlie encountered one in the South Indian Ocean in October 1815, more than 2,000 miles west-southwest of Tambora. The crew initially mistook the ash for seaweed, but when they approached they were shocked “to find it [composed of] burnt cinders, evidently volcanic. The sea was covered with it during the next two days.” As there was no land for hundreds of miles (and evidently being unable to believe that the pumice could have traveled that far) the crew attributed the field to an underwater eruption of unknown location.
At ten o’clock the magma columns—which now consisted almost entirely of molten rock and ash, most of the water having boiled away and evaporated—collapsed under their own weight. The eruption destroyed the top three thousand feet of the volcano, blasting it into the air in pieces, leaving behind only a large crater three miles wide and half a mile deep, as though the mountain had been struck by a meteor. Propelled by the force of the eruption, gray and black particles of ash, dust, and soot rose high into the atmosphere, some as high as twenty-five miles above the crumbling peak of the mountain, where the winds began to spread them in all directions. As they moved away from the eruption, the largest, heaviest particles lost their momentum first and began to fall back towards the ground. This gave the ash cloud the shape of a mushroom or an umbrella, with the still-erupting Tambora as the fiery shaft. The lightest particles in the cloud, however, retained their momentum and remained high in the air; some even continued to rise.
By eleven o’clock, the whirlwind had subsided. Only then did the explosions commence. At Bima, on the northeast coast of Sumbawa about forty miles east of Tambora, the British resident reported that the blasts sounded like “a heavy mortar fired close to his ear.” A rain of ash poured down upon the villages, heavy enough to crush the roofs of houses, including the resident’s, rendering them uninhabitable. Waves surged in from the sea, flooding houses a foot deep and ripping fishing boats from their moorings in the harbor, tossing them high up onto the shore. In place of dawn, there was only darkness.