Effects of the 1815 Tambora Eruption
to the Atmosphere and Climate
Dampak Erupsi Tambora 1815
terhadap Atmosfir dan Iklim
Igan S. Sutawidjaja
Geological Agency, Jln. Diponegoro 57 Bandung
ABSTRACT
The eruption of Tambora Volcano on the island of Sumbawa in 1815 is generally considered as the largest and most violent volcanic event in recorded history. The cataclysmic eruption occurring on 11 April 1815 was initiated by a plinian eruption on 5 April and killed more than 92,000 people in Sumbawa and nearby Lombok. It is well-known as the largest eruption in historical time. This event has an unprecedented impact on the Earth’s atmosphere as huge quantities of erupted ash and volcanic aerosols inferred with incoming solar radiation to the earth, causing global climate changes for one to two years. These changes were particularly well documented in temperate latitudes of the Northern Hemisphere. This catastrophic eruption was documented by a handful of British resident agents, a sea captain, and an army officer who were scattered in the Indonesian Archipelago. The aerosol cloud spread rapidly around the Earth in about three weeks and attained global coverage by about one year after the eruption. This caused dramatic decreases of the amount of net radiation reaching the Earth’s surface. Effects on the climate were an observed surface cooling in the Northern Hemisphere of up to 0.4 to 0.7o C, equivalent to a hemispheric-wide reduction in net radiation of 6 watts per square meter and a cooling of perhaps as large as -0.6oC over large parts of the Earth in 1816 and caused the year without a summer.
Keywords: Tambora volcano, volcanic ash, volcanic aerosol, climatic effect
SARI
Erupsi Gunung api Tambora di Pulau Sumbawa pada 1815 dianggap sebagai kejadian terbesar dan terdahsyat dalam catatan sejarah. Erupsi kataklismik yang terjadi pada 11 April 1815 diawali dengan erupsi plinian pada 5 April dan membunuh lebih dari 92.000 jiwa di sekitar Sumbawa dan Lombok. Erupsi ini terkenal sebagai letusan terbesar dalam kurun sejarah. Kejadian ini mempunyai dampak
yang tidak diketahui sebelumnya terhadap atmosfir bumi yaitu menghasilkan sejumlah besar abu
dan aerosol vulkanik, yang menutup radiasi sinar matahari terhadap bumi, sehingga menyebabkan perubahan iklim dunia dalam satu sampai dua tahun. Perubahan ini terdokumentasi baik di belahan
bumi bagian utara. Erupsi katastrofik ini juga tercatat oleh beberapa aparat residen, kapten laut, dan
perwira angkatan darat Inggris yang saat itu berada di sekitar Kepulauan Indonesia. Awan aerosol menyebar secara cepat ke sekeliling bumi dalam waktu tiga minggu, dan menutupi sekeliling dunia dalam 1 tahun setelah erupsi. Hal ini menyebabkan penurunan dramatis sejumlah jaringan radiasi yang mencapai permukaan bumi. Dampak perubahan iklim tersebut teramati dengan adanya penurunan
suhu permukaan di belahan utara mencapai 0,4o sampai 0,7o C, yang ekuivalen dengan reduksi luas
belahan dalam jaringan radiasi sebesar 6 watt per meter persegi, dan pendinginan sebesar -0,6o C
pada area yang luas di permukaan bumi pada tahun 1816, sehingga menimbulkan kehilangan musim panas pada tahun itu.
Figure 1. Locality map of Tambora Volcano in Sumbawa Island occupying most of the Sanggar peninsula northern part of Sumbawa Island.
INTRODUCTION
The Tambora Volcano situated in the northern part of Sumbawa Island occupies the Sanggar Peninsula (Figure 1). Eruption of the Tambora Volcano in 1815 is generally considered as the largest and most violent volcanic event in recorded history. The estimated loss of life in Sumbawa and nearby Lombok are about 92,000 and the volume of the erupted tephra has been estimated to be about 150 km3 (Stothers, 1984; Self et al., 1984; Sigurdsson and Carey, 1989). The ash fall was recorded at least 1,300 km from the source and the sound of the explosions was heard to 2,600 km in distance. A region extending up to 600 km west of the volcano was plunged into darkness up to three days. Stothers (1984) noted that tsunami of
Figure 2. Pyroclastic stratigraphy of the 1815 Tambora eruptive products at Tambora village. Dates to the right of the stratigraphic column indicate the inferred timing of the different eruptive phases based on historical reports. EJECTA OF 1815: VOLUMES
There are six layers could be distinguished surrounding the volcano and the volumes of the whole layers have been calculated; the lowest consisting of phreatomagmatic ash fall as the first product of the 1815 Tambora eruptive sequence is a gray, silty to sandy ash fall layer, which was distributed to the west of the volcano. It is 1-10 cm thick on the western flank of Tambora and eastern of Moyo Island and the volume of this layer is 0,09 km3. The second layer is a
plinian tephra fall, a pale-gray-green Plinian pumice fall deposit overlies the first layer and extends over a wide area to the west of Tambora. The layer is typically 10 to 30 cm thick on the slopes of the volcano and has a volume of 1.18 km3. The third layer
is a tephra fall containing sandy to silty pumice ash fall. The contact between the
two layers is sharp at proximal sites but becomes increasingly gradational at sites more than 50 km from the source. The unusual dispersal of this ash both to the east and west of Tambora may be a reflection of plume dispersal in both high- and low-altitude winds with the opposite polarity. The volume of the third layer is 0.32 km3.
The fourth layer is a Plinian tephra fall as the coarsest and most extensive of all the early fall deposits from the 1815 Tambora activity. The thickness of this layer is in excess of 20 cm over the entire western flank of Tambora, and the isopach of the fall deposit is strongly symmetrical to the volcano, elongated to the west. Closer to the volcano, however, the thickness remains relatively constant in the range of 25 to 30 cm and the volume of the deposit is about 3.02 km3. In these areas the pumice fall is
overlain by a surge deposit (Figure 2), and
Surface
Pyroclastic flow 1 - 4 meters
April 10 - 11
Pyroclastic surge April 10
Pre-April 5 April 5 April 5 - 10 April 10 Plinian pumice fall
Phreatomagmatic ash fall
Plinian pumice fall
Phreatomagmatic ash fall
Basement rock 2
1
it is believed that here the pumice fall has been eroded during passage of the surge (Sutawidjaja et al, 2006).
Volumes of the four early tephra deposits of the 1815 eruptive sequence have been determined from a combination of isopach maps and an extrapolation technique proposed by Sigurdsson (1989). Plots of isopach area versus isopach thickness were constructed for each of the fall layers. On plots of this type, tephra fall data can usually be subdivided into two linear segments (Sigurdsson, 1989) and the volume of a deposit can be found by integrating the area under the lines between two preselected thickness limits. For the Tambora deposits, the upper line segment has been adjusted so that the slope is the same as a line used by Wilson (1980) to calculate the volume of Taupo ultra-Plinian layer. This line when extrapolated to a thickness of 1 micron yielded the same volume as that determined
independently for the Taupo deposit by crystal-glass fractionation calculations (Wilson, 1980). The volume of the Tambora fall deposits were calculated with a lower integration thickness limit of one micron and an upper thickness limit based on proximal thickness measurements. Because it was not possible to subdivide the first and third layers at all localities, especially in the distal sections, only the bulk volume of the complete sequences has been calculated. With the exception of the first layer, about 70% of the volume of the fall deposits lies outside of the mapped area (Figure 3). The total volume of tephra deposited during the first through the fourth events was 4.6 km3 (DRE).
The large fragments of pumice thus are confined to the surrounding areas, while the finer ash particles were transported over a large area of the eastern Indonesia by the wind, which was primarily from the
E and NE during the days of the eruption. Sigurdsson (1989) calculated that the distribution of pyroclastic flows on the slopes of Tambora was estimated in total deposition area on land of 820 km2 and
874 km2 for pyroclastic flows and surges,
respectively, and all of the exposures show that pyroclastic flow deposits overlain surge deposits. The flows exceed a total thickness of 20 m, but the average is about 7 m, indicating a minimum subaerial volume of 5.7 km3.
Junghuhn (in Stothers, 1984) calculated the amount of material ejected by 1815 Tambora eruption, at 318 km3 of tephra fall
and pyroclastic flow deposits. The ash was several meters thick close to the volcano; in Lombok Island at 90 minutes distances from Tambora, 70 cm thick; in Banyuwangi, East Java, 210 minutes away from the volcano, 20 cm thick. Junghuhn draws a circle with a radius of 210 minutes around Tambora and assumes that the average thickness of the ash within this circle was 60 cm. But because the wind was mainly from the E, and the finer material was there for largely carried to the W (Lombok, Bali and Banyuwangi), the assumption that sixty centimeters of ash fell everywhere is too high for the areas for the areas situated E, N, and S of Tambora. Javasche Courant reported that the ash layer was only 0,1 m thick in Bima, 60 km E of the volcano; and only 0.03 m in Makassar, 270 km N of Tambora. According to Simkin and Fiske (1983) Junghuhn’s calculation therefore give apparently much too high. It is more likely that the ash deposit with an average thickness of 60 cm, only fell in a rectangle of approximately 150 minutes wide and 300 minutes long, with Tambora located close to the eastern end of this rectangle. Simkin and Fiske (1983) then obtain: J = 2/3 x 150 x 300 x (1855 x 1855)
km3/109 = 103 km3. If it takes another 50%
for the material falling outside of it, which
definitely is high, then Simkin still obtains 150 km3.
EJECTA OF 1815: ITS ATMOSPHERIC EFFECTS
Radiative forcing the climate system by stratospheric aerosols depends on the geographic dist aerosol distribution, altitude, size distribution, and optical depth of the aerosols, but tropospheric temperatures are most strongly dependent on the total optical depth (Lacis et al., 1992). This cloud injected about 25 Mt of SO2 into the stratosphere, and this SO2 immediately began to convert into H2SO4 aerosols to the stratospheric aerosol layer. Using a forcing in the model equivalent to a global mean of about 0.15 based on conditions appropriate for the Pinatubo cloud yielded a model radiative forcing at the tropopause of -4 W/m2 (Hansen et al.,
1992). This study shows that the temperature anomaly after Tambora is about -0.4 to -0.7 degrees cooler than the average over a large part of the Earth (Stothers et al., 1984). Certainly, in terms of widespread impact, due to its equatorial location, the early summer date of eruption, and the resulting global spread of the aerosol cloud, the peak optical depth attained by the widespread aerosol cloud, estimated to be >1.0 in northern latitudes is six month after the eruption. The Tambora aerosol cloud that enveloped the Earth from the end of April 1815 to late 1816 (Figure 4) is the largest that followed by the approximately 10 km3 Krakatau eruption
CONCLUSIONS
The 1815 eruption of Tambora produced
about 318 km3 of dacitic magma, and this
is the largest volume in historical time. Eruption columns rising above the vent reached in excess of 33 to 43 km in altitude and emplaced a giant umbrella cloud in the middle to upper stratosphere that attained a maximum dimension of over 1,000 km in diameter, and this cloud injected about
25 Mt of SO2 into the stratosphere. The aerosol cloud and ash materials spread rapidly around the globe in about three weeks and attained the global coverage one year after the eruption caused the year without a summer. Effect to the climate is the cooling in the Northern Hemisphere as large as -0.7oC over large parts of the Earth
in 1815-1816.
Global impact of Tambora eruption was profound to the people in the Northern
a
Figure 4. Schematic diagram how the aerosol cloud and ash materials spread rapidly around the globe in about three weeks and attained global coverage 1 year after the eruption caused the year without a summer(Courtesy Discovery Channel).
Tabel 1. Comparison of Volcanic Aerosol ejected from the Volcanoes
Volcano Location Age (Megaton)Aerosol Reference
Tambora Indonesia 1815 40-60 Stothers, 1984
Krakatau Indonesia 1883 30-50 Rampino and Self, 1982
El-Chichon Mexico 1982 17 Rampino and Self, 1984
Hemisphere that starved to death because they lost their summer during the year, and the volcanic aerosols changed the climate. For the next large volcanic eruptions, these aerosols will produce acid rain, endangering skin and irritation of eyes.
ACKNOWLEDGMENTS
This paper is compiled from the fieldwork data and
secondary data. The author thanks colleagues who supported to write this paper.
REFERENCES
Hansen, J., Lacis, A., Ruedy, R., and Sato, M., 1992. Potential climate impact of the Mount Pinatubo eruption. Geophysical Research Letter, 19, p.215-218.
Lacis, A., Hansen, J., and Sato, M., 1992, Climate forcing by stratospheric aerosols. Geophysical Research Letter, 19, p.1607-1610.
Newhall, C.G. and Punongbayan, R.S., 1996. Fire and mud, eruptions and lahars of Mt. Pinatubo, Philippines. University of Washington Press, Seattle and London, 1126pp.
Rampino, M.R. and Self, S., 1982. Historic eruptions of Tambora (1815), Krakatau (1883), and Agung
(1963), their stratospheric aerosols and climatic impact. Quaternary Research, 18, p.127-143.
Rampino, M.R. and Self, S., 1984. The atmospheric effects of El Chichon. Scientific American, 250, p.48-57.
Self, S., Rampino, M., Newton, M., and Wolff, J., 1984. Volcanological study of the great Tambora eruption of 1815. Geology, 12, p.659-663.
Sigurdsson, H. and Carey, S., 1989. Plinian and co-ignimbrite tephra fall from the 1815 eruption of Tambora volcano. Bulletin of Vulcanology, 51, p.243-270.
Simkin, T. and Fiske, R.S., 1983. Krakatau 1883, the volcanic eruption and its effects. Smithsonian Institution Press, Washington D.C.
Stothers, R.B., 1984. The great Tambora eruption in 1815 and its aftermath. Science, 224, p.1191-1198.
Sutawidjaja, I.S., Sigurdsson, H., and Abrams, L., 2006. Characterization of Volcanic Deposits and Geoarchaeological Studies from the 1815 Eruption of Tambora Volcano. Journal Geologi Indonesia, 1(1), p.49-57.
