Earthquakes occur when tectonic plates shift beneath the Earth's surface, causing the ground to shake and sometimes displace. Large offshore earthquakes can displace the seabed enough to create tsunamis. Earthquakes may also trigger landslides or volcanic eruptions in rare cases. Volcanic eruptions happen when gas and magma build up underground, releasing lava, rocks, and ash during more explosive eruptions. Eruptions with less gas and thicker magma tend to be less dramatic and result in lava flows from the vent.

1. Volcanoes and earthquakes
At the Earth's surface, earthquakes manifest
themselves by shaking and sometimes
displacement of the ground. When the
epicenter of a large earthquake is located
offshore, the seabed may be displaced
sufficiently to cause a tsunami. Earthquakes
can also trigger landslides, and occasionally
volcanic activity.

2. Volcanoes and earthquakes

3. Volcanoes and earthquakes
When thick magma and large amounts of gas
build up under the surface, eruptions can be
explosive, expelling lava, rocks and ash into the
air. Less gas and more viscous magma usually
mean a less dramatic eruption, often causing
streams of lava to ooze from the vent.

4. Volcanoes and earthquakes