April 10, 1815 Tsunami: Tambora, Indonesia

Reference #414:

On April 10 (mistakenly 4), 1815 there was an explosion of the Tambora Volcano on Sumbawa Island which was thought to be extinct. It was the strongest explosion in historical times in Indonesia. It was accompanied by considerable oscillations in sea level. The eruption began on April 1. At 22:00 [local time] at Bajuwangi (Java Island), a cannonade boomed out like peals of distant thunder. It was repeated from time to time, and this continued until 9:00 on the 2nd. On the morning of the 3rd, a light fall of ashes began; on the 5th, explosions began to be heard at 1/4 hour intervals.

The eruption reached its peak on the evening of the 10th, when a colossal pillar of smoke rose above the volcano and the entire mountain seemed to eject flame. Soon the volcano and all that occurred there were hidden in a dense cloud of smoke.

The sound of a shot was so loud that it was heard for an enormous distance: from Bengkulu and Banka Island in the west to Ternate Island in the east. At Surabaja, the air wave uprooted trees, destroyed the walls of homes, and bowled over people and animals. The tremors were felt more or less strongly at Banjuwangi, Sumenep, Surakarta, Rembang, apparently on the southeast of Kalimantan Island, at Makassar and on Flores Island.

Scorching hot slag and ashes covered all of Sumbawa Island and a sizeable water area. Buildings collapsed under this load. The previously picturesque island was turned into a desolate desert. Of 12,000 residents, only 26 survived. On neighboring Lombok Island, the depth of the layer of ashes was 0.5 m. A similar layer of ashes was floating at sea west of Sumbawa Island on the 12th. On Java Island, the ashfall was so dense that complete darkness set in. The ashes fell on Java at a distance of 550 km from the volcano; it also fell on Sulawesi Island at Ambon. From this one can conclude that the ash was ejected to a very great height, as otherwise it would have been carried by the trade winds only to the west.

On the 10th, with still weather, the sea off the coast of Sumbawa Island suddenly rose to a height of 0.5 to 3.5 m. Large waves burst into the estuaries of the rivers and immediately surged back. Here and there homes and trees were washed away. At Bima, the water submerged the floors of homes by 0.3 m. All the proas and boats were torn from their anchors and tossed onshore. The coast at the Tambora volcano subsided so that water 5-6 m deep appeared in place of the land.

Short-period (duration no more than 3 minutes) oscillations in level were noted on Sulawesi and Java Islands. At Sumenep, on the 11th at 19:00 during an ebb tide, a flood tide of water from the bay made the river rise 1-1.5 m; then the level fell for 4 minutes.

The explosions of the volcano, which were accompanied by strong tremors, lasted several more days. Eruption finally came to an end only on July 15.

Reference #132:

1815, April 10. Dutch East Indies, Sumbawa, east of Java, Bima. Powerful wave 12 feet high.

Reference #9675:

Approximately 11,000 direct deaths from bomb impacts, tephra falls, and tsunamis; recent work indicates pyroclastic flows reached all but W coast and probably caused most direct fatalities on Sumbawa.

Indirect effects: An estimated 49,000 persons died of famine and disease on Sumbawa and Lombok islands following the eruption. This replaces an earlier estimate of 82,000.