Lake Toba in the context of "Volcanic lake"

A supervolcano is a volcano that has had an eruption with a volcanic explosivity index (VEI) of 8, the largest recorded value on the index. This means the volume of deposits for such an eruption is greater than 1,000 cubic kilometers (240 cubic miles).

Supervolcanoes occur when magma in the mantle rises into the crust but is unable to break through it. Pressure builds in a large and growing magma pool until the crust is unable to contain the pressure and ruptures. This can occur at hotspots (for example, Yellowstone Caldera) or at subduction zones (for example, Toba).

The Toba (also known as Toba Batak) people (Batak Toba: ᯅᯖᯂ᯲ ᯖᯬᯅ) are one of the sub-ethnic groups of the Batak people, found mainly in North Sumatra, Indonesia. The general term "Batak" is sometimes used to refer to the Batak Toba people, for one thing because the Toba people are the largest sub-group of the Batak ethnicity, for another because they tend to self-identify as merely Batak instead of "Toba" or "Toba Batak", contrary to the habit of the Mandailing, Angkola, Karo, Simalungun and Pakpak communities who commonly self-identify with their respective sub-groups. Religiously, they predominantly adhere to Protestantism of Christianity.

The Toba people are found in Toba Regency, Humbang Hasundutan Regency, Samosir Regency, North Tapanuli Regency, Central Tapanuli Regency (with Sibolga and its surrounding regions), and part of Dairi Regency. The Batak Toba people speak the Toba Batak language and are centered on Lake Toba and Samosir Island within the lake. Batak Toba people frequently build in traditional Batak architecture styles which are common in Samosir. Cultural demonstrations, performances, and festivities such as Sigale Gale are often held for tourists.