The 1815 Eruption of Mount Tambora was one of the most powerful eruptions in recorded history and is classified as a VEI-7 event. The eruption of the volcano, on the island of Sumbawa in the Dutch East Indies (present-day Indonesia), reached a climax on 10 April 1815 and was followed by between six months and three years of increased steaming and small phreatic eruptions.
The eruption column lowered global temperatures, and some experts believe this led to global cooling and worldwide harvest failures, sometimes known as the Year Without a Summer in 1816. The eruption resulted in a brief period of significant climate change that led to various cases of extreme weather. Several climate forcings coincided and interacted in a systematic manner that has not been observed since, despite other large eruptions that have occurred since the early Stone Age. Although the link between the post-eruption climate changes and the Tambora event has been established by various scientists, the understanding of the processes involved is incomplete.
Chronology of the Radiocarbon dating has established the dates of three of Mount Tambora’s eruptions before the 1815 eruption. The magnitudes of these eruptions are unknown. The estimated dates are 3910 BC ± 200 years, 3050 BC and 740 AD ± 150 years. They were all explosive central vent eruptions with similar characteristics, but the 740 AD eruption had no pyroclastic flows.
In 1812, Mount Tambora entered a period of high activity, with its climactic eruption being the catastrophic explosive event of April 1815
Mount Tambora is still active. Minor lava domes and flows have been extruded on the caldera floor during the 19th and 20th centuries.The last eruption was recorded in 1967. However, it was a very small, non-explosive eruption (VEI = 0).
There were reports of a similarly small eruption in 2011.
The 1815 VEI-7 eruption had a total tephra ejecta volume of 160 km3 (38 cu mi). It was an explosive central vent eruption with pyroclastic flows and a caldera collapse, causing tsunamis and extensive land and property damage. It had a long-term effect on global climate. This activity ceased on 15 July 1815. Follow-up activity was recorded in August 1819 consisting of a small eruption (VEI = 2) with flames and rumbling aftershocks, and was considered to be part of the 1815 eruption sequence. Around 1880 ± 30 years, Tambora went into eruption again, but only inside the caldera. Small lava flows and lava dome extrusions were formed. This eruption (VEI = 2) created the Doro Api Toi parasitic cone inside the caldera. This was the largest and most violent eruptions in the last 5000 years along with the Hatepe eruption of Lake Taupo at around 180 AD and the Tianchi eruption of Baekdu around 1000.
Archaeological evidence indicates that the 1815 eruption of Mount Tambora wiped out a culture on Sumbawa
scientific team led by a Swiss botanist, Heinrich Zollinger, arrived on Sumbawa in 1847, making an ascent to the eastern rim of the caldera with the help of a native team. Zollinger’s mission was to study the eruption scene and its effects on the local ecosystem. He was the first person to climb to the summit after the eruption. It was still covered by smoke. As Zollinger climbed up, his feet sank several times through a thin surface crust into a warm layer of powder-like sulphur. Some vegetation had reestablished itself and he saw a few trees on the lower slope. A Casuarina forest was noted at 2,200–2,550 m (7,220–8,370 ft). Several Imperata cylindrica grasslands were also found.
Resettlement of the mountain began in 1907. A coffee plantation was started in the 1930s on the northwestern slope of the mountain, in the village of Pekat. A dense rain forest, dominated by the pioneering tree Duabanga moluccana, had grown at an altitude of 1,000–2,800 m (3,300–9,200 ft). It covers an area up to 80,000 ha (200,000 acres). The rain forest was explored by a Dutch team, led by Koster and de Voogd, in 1933. From their accounts, they started their journey in a “fairly barren, dry and hot country”, and then they entered “a mighty jungle” with “huge majestic forest giants”. At 1,100 m (3,600 ft), they entered a montane forest. Above 1,800 m (5,900 ft), they found Dodonaea viscosa dominated by Casuarina trees. On the summit, they found sparse Anaphalis viscida and Wahlenbergia.
In 1896, 56 species of birds were found, including the crested white-eye. Twelve further species were found in 1981. Several other zoological surveys followed, and found other bird species on the mountain, resulting in over 90 bird species discovered on Mount Tambora. Yellow-crested cockatoos, Zoothera thrushes, hill mynas, green junglefowl and rainbow lorikeets are hunted for the cagebird trade by the local people. Orange-footed scrubfowl are hunted for food. This bird exploitation has resulted in a decline in the bird population. The yellow-crested cockatoo is nearing extirpation on Sumbawa island.
Since 1972, a commercial logging company has been operating in the area. The logging company holds a timber-cutting concession for an area of 20,000 ha (49,000 acres), or 25% of the total area. Another part of the rain forest is used as a hunting ground. In between the hunting ground and the logging area, there is a designated wildlife reserve where deer, water buffalos, wild pigs, bats, flying foxes, and various species of reptiles and birds can be found.
In 2015 the conservation area protecting the mountain’s ecosystem has been upgraded to the status of national park.
An ecosystem has developed in the caldera formed by the 1815 eruption. This ecosystem has been largely uninfluenced by human beings because of its isolation.
In October 2013, a German research team (Georesearch Volcanedo Germany, GRV) carried out the first lengthy expedition into this 1300m deep caldera. The GRV team and a team of native helpers climbed down the inner southern wall under extreme conditions. They climbed down from 2430m to 1340m altitude to reach the caldera floor. The team stayed within the Tambora caldera for nine days, researching the caldera floor. Very few people had reached the caldera floor before this, as descending the steep walls is difficult and dangerous, subject to earthquakes, landslides and rockfalls. Moreover, only relatively short stays on the caldera floor had been possible due to logistical problems, so that extensive studies had been impossible.
The investigation program of Georesearch Volcanedo on the caldera floor included researching the visible effects of the smaller eruptions which had taken place on the caldera floor since 1815, temperature measurements (air, soil, gases), gas measurements, studies of flora and fauna, and measurement of weather data. Especially striking was the relatively high activity of Doro Api Toi (Gunung Api Kecil means “small volcano”) in the southern part of the caldera and the gases escaping under high pressure and loud noises on the lower north-east wall.
In July 2014, the same research team from Georesearch Volcanedo Germany carried out a further expedition into the Tambora caldera, spending over 12 days continuing and expanding on their research of the previous year.
In August 2015, 200 years after the big eruption, the team of Georesearch Volcanedo Germany (GRV) and a team of native helpers followed the route used by Zollinger and explored this area for the first time since 1847. Even though there were no geographic coordinates of Zollinger’s ascent, the GRV team followed Zollinger’s descriptions and his historical-drawn map.
The ascent of Mount Tambora from the east coast of the Sanggar peninsula up to the eastern rim was a particular challenge in both 2015 and 1847. The lengthy distance to be travelled on foot, the difficult terrain, the high daily temperatures, the usual water shortage in this region in August and the high demand of drinking water during such an expedition required a detailed logistical preparation.
Indonesia’s population has been increasing rapidly since the 1815 eruption. As of 2006, the population of Indonesia has reached 222 million people, of which 130 million are concentrated on Java. A contemporary volcanic eruption as large as Tambora’s 1815 eruption would cause catastrophic devastation with likely many more fatalities. Therefore, volcanic activity in Indonesia is continuously monitored, including that of Mount Tambora.
Seismic activity in Indonesia is monitored by the Directorate of Volcanology and Geological Hazard Mitigation, Indonesia. The monitoring post for Mount Tambora is located at Doro Peti village. They focus on seismic and tectonic activities by using a seismograph. Since the 1880 eruption, there has been no significant increase in seismic activity. However, monitoring is continuously performed inside the caldera, especially around the parasitic cone Doro Api Toi.
The directorate has defined a hazard mitigation map for Mount Tambora. Two zones are declared: the dangerous zone and the cautious zone. The dangerous zone is an area that will be directly affected by an eruption: pyroclastic flow, lava flow and other pyroclastic falls. This area, including the caldera and its surroundings, covers up to 58.7 km2 (22.7 sq mi). Habitation of the dangerous zone is prohibited. The cautious zone includes areas that might be indirectly affected by an eruption: lahar flows and other pumice stones. The size of the cautious area is 185 km2 (71 sq mi), and includes Pasanggrahan, Doro Peti, Rao, Labuan Kenanga, Gubu Ponda, Kawindana Toi and Hoddo villages. The river Guwu at the southern and northwest part of the mountain is also included in the cautious zone.