Supervolcanic

But scientists say the Toba supervolcanic eruption, which took place some 74,000-75,000 years ago in an area that is now home to Lake Toba in Sumatra, Indonesia was one the largest known VEI 8 volcanic eruptions ever to take place on Earth.

Earthquakes and increased geothermal phenomena don't necessarily point to a pending supervolcanic eruption.