Four separate eruptions have occurred from vents within the present collapse structure, which formed from eruption of the 2800 km 3 youngest toba tuff ytt at 74 ka. Eruption of the three older toba tuffs alternated from calderas situated in northern and. The feeder system of the toba supervolcano from the slab. Distribution of magma beneath the toba caldera complex, north. These new determinations, in conjunction with previous ages for the two oldest tuffs at toba, establish the chronology of four eruptive events from the toba caldera complex over the past 1. A large magmatic sill complex beneath the toba caldera this copy is for your personal, noncommercial use only. A large magmatic sill complex beneath the toba caldera science. The enigmatic origin and emplacement of the samosir island.
We used ambientnoise seismic tomography below the toba caldera in northern sumatra to observe the anisotropy that we interpret as the. Abstract the toba caldera in indonesia is one of the most remarkable volcanic features formed during quaternary geologic time. Stratigraphy of the toba tuffs and the evolution of the. Distribution of magma beneath the toba caldera complex, north sumatra, indonesia, constrained by threedimensional p wave velocities, seismicity, and gravity.
These data indicate that samosir island, the upper surface of which was the floor of the caldera that collapsed 74 ka during the young toba tuff eruption, was submerged beneath lake level 900 m a. In light of this, it seems likely that by the time of the toba event, modern humans had already developed a suite of riskmanagement. The toba caldera is the site of the largest pleistocene eruption at 74,000 years ago, yet the magmatic plumbing system remains poorly understood. Volcanology ascentmechanismoflargemagmavolumesthrough. Petrogenesis of the toba tuffs, sumatra, indonesia. Eruption of the three older toba tuffs alternated from calderas situated in northern and southern. Ten samples from the toba caldera complex were collected from four different groups eight samples from three distinct lava domeflow regions around toba caldera and. The two lines marked aa0 and bb0 note the locations of the cross sections shown in. Converted wave imaging of the toba caldera, indonesia. Post caldera lavas at the toba caldera, sumatra,indonesia. Post74 ka activity at toba caldera, sumatra, indonesia. P and s velocity structure beneath the toba caldera complex northern sumatra from local earthquake tomography 5 10 15 20 25 ivan koulakov 1, 2.
Available online xxx abstract the toba caldera in indonesia is one of the most remarkable volcanic features formed during quaternary geologic time. The mass it threw out was 100 times greater than the largest volcanic eruption in recent history. It made a sizable contribution to the 100x30 km caldera complex. The supereruption of toba, did it cause a human bottleneck. Eruptive history of earths largest quaternary caldera. Stratigraphy of the toba tuffs and the evolution of the toba caldera. Figure 3 from the toba caldera complex semantic scholar. The toba caldera complex, north sumatra, indonesia, was the source of one of earth s largest rhyolite ashflow eruptions at 0. The lake is located in the middle of the northern part of the island of sumatra, with a surface elevation of about 900 metres 2,953 ft, the lake stretches from 2. Toba catastrophe theory wikimili, the best wikipedia reader. The steepwalled caldera contains lake toba, the largest volcanic lake on the planet. The toba caldera complex in northern sumatra was the site of 4 caldera forming eruptions in the past 1. It had an estimated volcanic explosivity index of 8 described as apocalyptic.
At a depth of 5 km, the high v p v s patterns are rather small in size 715 km and coincide with. A melt inclusion study of the middle and oldest toba tuffs. Pdf distribution of magma beneath the toba caldera complex. A large magmatic sill complex beneath the toba caldera. Graduate thesis or dissertation investigating timescales. Beneath the toba caldera and other volcanoes of the arc, we observe relatively moderate for volcanic areas negative p and svelocity anomalies that reach 18 per cent in the uppermost layer, 1012 per cent in the lower crust and about 7 per cent in the uppermost mantle. Erupting at least 2800 km3 of magma in a single event 74,000 years ago, it. The 100x30km topographic depression sits astride a broad region of uplift in the nw extension of the sunda arc. A large magmatic sill complex beneath the toba caldera k.
If you wish to distribute this article to others, you can order highquality copies for your following the guidelines here. Its rich history of research for over a century has yielded important information on the physical volcanology of silicic calderas and supereruptions, geochemical evolution of silicic magma bodies, and geophysical imaging of active subvolcanic systems. Geological society of america abstracts with programs 28, 32. Resurgent tobafield, chronologic, and model constraints. Beneath the toba caldera, we observe a very high value of v p v s that reaches 1.
The toba supereruption was a supervolcanic eruption that occurred about 75,000 years ago at the site of presentday lake toba in sumatra, indonesia. Grey shading is the outline of the composite caldera. We have estimated the possible macromechanical properties of such media via the modeling of seismic velocities in random layered structures 15, 21. The toba caldera complex in northern sumatra is a 100 3 30 km topographic depression of several overlapping calderas resulting from four major eruptions during the quaternary e.
Chesner department of geologygeography, eastern illinois university, charleston, il 61920, united states article info article history. Discover the toba caldera in ronggur nihuta, indonesia. Distribution of magma beneath the toba caldera complex. A supervolcano is a large volcano that has had an eruption with a volcanic explosivity index vei of 8, the largest recorded value on the index. The model presented here for the formation and evolution of the toba caldera complex, utilizes the contributions of many researchers who have sought to explain the origin of the kesselbruch basin generated by collapse along arcuate faults for the past 117 years. A volcanic ash layer occurs just above the australasian microtektite layer, which some authors suggest is from a supereruption of the toba caldera complex. Frontiers resurgent tobafield, chronologic, and model. Pdf distribution of magma beneath the toba caldera. Site of the largest volcanic eruption in the last 25 million years, one which may have nearly wiped out humanity altogether.
Caldera walls rise steeply 4001200 m above the 1700 sq km lake, which is one of the worlds deepest, with a maximum depth of 530 m. This could be an indicator of a dominant effect of melting in the origin of seismic anomalies in the crust and uppermost mantle beneath the toba caldera. P and s velocity structure beneath the toba caldera. The lake is about 100 kilometres long, 30 kilometres 19 mi wide, and up to 505 metres 1,657. S9 can be explained by a large layered intrusion complex that is dominated by horizontally oriented sills. The toba caldera complex of northern sumatra, the largest quaternary caldera on earth, has generated three voluminous and compositionally similar rhyolitic tuffs, viz. The anisotropy below 7 km in depth appears to be due to a layered magmatic intrusion dominated by horizontally oriented sills. Toba is situated along the crest of this regional feature. Toba catastrophe simple english wikipedia, the free. Luehr2 and wandono 4 1institute of petroleum geology and geophysics, sb ras, prospekt akademika koptuga, 3, novosibirsk, 630090, russia. Distribution of magma beneath the toba caldera complex, north sumatra, indonesia, constrained by threedimensional p wave velocities, seismicity, and gravity data. Rhyolite caldera complexes volcano world oregon state. It is based upon the identification, distribution, geochemistry, and.
They are usually so explosive when they erupt that they end up collapsing in on themselves rather than building any tall structure george walker has termed such structures inverse volcanoes. Joint body and surface wave tomography applied to the toba. P, s velocity and vpvs ratio beneath the toba caldera. Department of geology and geography, eastern illinois university. Carbon14 dating, lake sediments, toba caldera, resurgence, numerical modeling, magmatic. Because the previously known tuktuk and samosir fault lava domes occur near the base of a major resurgent dome fault, they appear associated with resurgent uplift, and dating them could provide constraints on the timing of resurgence. Erupting at least 2800 km3 of magma in a single event. The toba caldera in indonesia is one of the most remarkable volcanic features formed during quaternary geologic time. The toba caldera ronggur nihuta, indonesia atlas obscura.
The eruption left a caldera 100 kilometers 62 miles long, 29 kilometers 18. The toba caldera complex of northern sumatra, indonesia fig. The toba caldera on the indonesian island of sumatra is the newest resurgent caldera, created roughly 74,000 years ago by the largest volcanic eruption in the last 25 million years. Toba caldera complex, north sumatra, indonesia, modified after knight et al. The radial anisotropy within the middle crust below the toba caldera fig. Rhyolite caldera complexes are the most explosive of earths volcanoes but often dont even look like volcanoes. Beneath the toba caldera and other volcanoes of the arc, we observe relatively moderate for volcanic areas negative p. Lake toba is a large natural lake in sumatra, indonesia occupying the caldera of a supervolcano. The toba catastrophe theory holds that this event caused a global volcanic winter of six to ten years and possibly a 1,000yearlong cooling episode. This massive eruption ejected 2,800 cubic kilometers 1,740 cubic miles of debris. Available online xxx abstract the toba caldera in indonesia is one of the most remarkable volcanic. Australasian microtektites and associated impact ejecta in.
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