Why Do Volcanoes Erupt? | A2 ESL Science Reading Passage

Use this A2-B1 ESL science reading passage to learn why volcanoes erupt. It includes key vocabulary, reading comprehension questions, and answers for English learners.

Volcanoes erupt when magma, gas, and pressure build up under Earth's surface.

Reading Level

A2-B1

Word Count

292 words

Reading Passage

A volcano is an opening in Earth's surface. Sometimes hot melted rock, gas, and ash come out of this opening. This event is called an eruption.

Deep under the ground, some rock is so hot that it melts. This melted rock is called magma. Magma can collect in spaces under a volcano.

Magma often contains gases. As more magma and gas build up, pressure can grow. You can think of pressure like air inside a balloon. If the pressure becomes too strong, the balloon may burst. In a volcano, strong pressure can push magma upward.

Magma looks for a weak place to escape. It may move through cracks in the rock. When magma reaches Earth's surface, it is called lava. Lava can flow down the sides of a volcano.

Some eruptions are quiet, with lava moving slowly. Other eruptions are explosive. Explosive eruptions can send ash, rock, and gas high into the air. The type of eruption depends on the magma, gases, and pressure inside the volcano.

Volcanoes often form near the edges of tectonic plates. These plates are huge pieces of Earth's outer layer. When plates move, they can create places where magma rises.

Volcanoes can be dangerous, but they also help shape Earth. Over time, lava can cool and become new rock. Some islands and mountains were made by volcanoes.

Magma and gas create pressure that can push lava out of a volcano.

Key Vocabulary

Word	Meaning	Example
volcano	an opening in Earth's surface where hot material can come out	The volcano erupted at night.
magma	hot melted rock under Earth's surface	Magma can collect under a volcano.
pressure	force made when something pushes against something else	Pressure pushed the magma upward.
lava	hot melted rock that comes out of a volcano	Lava flowed down the mountain.
eruption	an event when material comes out of a volcano	The eruption sent ash into the sky.

Reading Comprehension Questions

1. What is a volcano?
2. What is magma?
3. Why can pressure grow under a volcano?
4. What is magma called when it reaches Earth's surface?
5. How can volcanoes help shape Earth?

Answers

1. A volcano is an opening in Earth's surface.
2. Magma is hot melted rock under Earth's surface.
3. Pressure can grow when magma and gases build up.
4. Magma is called lava when it reaches Earth's surface.
5. Lava can cool and become new rock, helping form land, islands, and mountains.

Short Summary

Volcanoes erupt when magma, gas, and pressure build up under Earth's surface. The material escapes through weak places and can come out as lava, ash, and gas.

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