How was Toba volcano formed?
The 35 x 100 km Toba volcano, the Earth’s largest Quaternary caldera, was formed during four major Pleistocene ignimbrite-producing eruptions beginning at 1.2 million years ago. Resurgent doming formed the massive Samosir Island and Uluan Peninsula structural blocks after the YTT eruption.
What types of tectonic boundaries experience volcanism?
Volcanoes are most common in these geologically active boundaries. The two types of plate boundaries that are most likely to produce volcanic activity are divergent plate boundaries and convergent plate boundaries. At a divergent boundary, tectonic plates move apart from one another.
Why is Lake Toba geologically significant?
Lake Toba is the site of a supervolcanic eruption estimated at VEI 8 that occurred 69,000 to 77,000 years ago, representing a climate-changing event. It is the largest-known explosive eruption on Earth in the last 25 million years.
Was Mount Toba a supervolcano?
The Youngest Toba eruption was a supervolcanic eruption that occurred around 75,000 years ago at the site of present-day Lake Toba in Sumatra, Indonesia. It is one of the Earth’s largest known explosive eruptions. The Youngest Toba eruption is the most closely studied supervolcanic eruption.
What are the three main tectonic settings for volcanism on Earth?
As summarized in Chapter 3, magma is formed at three main plate-tectonic settings: divergent boundaries (decompression melting), convergent boundaries (flux melting), and mantle plumes (decompression melting). The mantle and crustal processes that take place in areas of volcanism are illustrated in Figure 4.4.
What is a tectonic setting?
Tectonic Settings: Plate tectonics is the large scale movement of Earth’s crust, and results in a number of distinct geologic settings.
What is the measured uplift at Toba?
An average rate of uplift was calculated at ~1.9 cm/year, although an arbitrary duration of 1000 years could be used to suggest rates of 100 cm/year (Phillips et al., 2007 end of their page 10).
What type of plate boundary is Lake Toba?
[2] The Toba caldera is located in north Sumatra, Indonesia. It is part of the volcanic arc associated with the subduction of the Australian Plate beneath the Southeast-Asian Plate. The subduction zone, and the Sumatra Fault, a right lateral strike-slip fault which marks the plate boundary, are seismically active.
Where do volcanoes form in a subduction zone?
Composite volcanoes form at subduction zones, either on ocean-ocean convergent boundaries (left) or ocean-continent convergent boundaries (right). Both shield volcanoes and cinder cones form in areas of continental rifting. Shield volcanoes form above mantle plumes, but can also form at other tectonic settings.
Can a shield volcano form above a mantle plume?
Shield volcanoes form above mantle plumes, but can also form at other tectonic settings. Sea-floor volcanism can take place at divergent boundaries, mantle plumes and ocean-ocean-convergent boundaries. [SE, after USGS (http://pubs.usgs.gov/gip/dynamic/Vigil.html)]
How are mantle and crustal processes related to volcanism?
The mantle and crustal processes that take place in areas of volcanism are illustrated in Figure 4.4. At a spreading ridge, hot mantle rock moves slowly upward by convection (cm/year), and within about 60 km of the surface, partial melting starts because of decompression.
