Geothermal energy is an important source of energy in -- (sunny/volcanically-active) places.

Explanation

**Step-by-Step Solution:**

1. **Understanding Geothermal Energy**: Geothermal energy refers to the heat that is stored beneath the Earth's surface. This heat originates from the Earth's inner core, which can reach temperatures of about 12,000 degrees Celsius.

2. **Formation of Geothermal Energy**: The intense heat from the Earth's core can cause the tectonic plates in the upper layer of the Earth to crack. When these cracks occur, magma (which is molten rock) can rise to the surface.

3. **Volcanic Activity**: The rising magma can lead to volcanic eruptions. When a volcano erupts, it releases heat and energy that can be harnessed for various uses.

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