A moderate-sized eruption on 5 April 1815 was followed by thunderous detonation sounds that could be heard in Ternate on the Molucca Islands, from Mount Tambora. On the morning of 6 April 1815, volcanic ash began to fall in East Java, with faint detonation sounds lasting until 10 April. What was first thought to be the sound of firing guns was heard on 10 and 11 April on Sumatra island (more than away), Cited by Oppenheimer (2003) and possibly over 3350 km (2060 miles) away in Thailand and Laos. The eruptions intensified at about 7:00 p.m. on the 10th. Three plumes rose and merged. Pieces of pumice of up to in diameter rained down at approximately 8 p.m., followed by ash at around 9–10 p.m. The eruption column collapsed, producing hot pyroclastic flows that cascaded down the mountain and towards the sea on all sides of the peninsula, wiping out the village of Tambora. Loud explosions were heard until the next evening, 11 April. The veil of ash spread as far as West Java and South Sulawesi, while a "nitrous odor" was noticeable in Batavia. The heavy tephra-tinged rain did not recede until 17 April. Analysis of various sites on Mount Tambora using ground-penetrating radar has revealed alternations of pumice and ash deposits covered by the pyroclastic surge and flow sediments that vary in thickness regionally.
A moderate-sized eruption on 5 April 1815 was followed by thunderous detonation sounds that could be heard in Ternate on the Molucca Islands from Mount Tambora On the morning of 6 April 1815 volcanic ash began to fall in East Java with faint detonation sounds lasting until 10 April What was first thought to be the sound of firing guns was heard on 10 and 11 April on Sumatra island (more than away) Cited by Oppenheimer (2003) and possibly over 3350 km (2060 miles) away in Thailand and Laos The eruptions intensified at about 700 pm on the 10th Three plumes rose and merged Pieces of pumice of up to in diameter rained down at approximately 8 pm followed by ash at around 9–10 pm The eruption column collapsed producing hot pyroclastic flows that cascaded down the mountain and towards the sea on all sides of the peninsula wiping out the village of Tambora Loud explosions were heard until the next evening 11 April The veil of ash spread as far as West Java and South Sulawesi while a "nitrous odor" was noticeable in Batavia The heavy tephra-tinged rain did not recede until 17 April Analysis of various sites on Mount Tambora using ground-penetrating radar has revealed alternations of pumice and ash deposits covered by the pyroclastic surge and flow sediments that vary in thickness regionally