Plate Boundaries, Volcanoes, and Earthquake Impacts

Types of Plate Boundaries

1) Constructive or Divergent

Two plates are moving apart from each other. New magma rises to the surface to fill the gap and cools to form basalt. Lava forms volcanoes and rift valleys.

2) Destructive or Convergent

Two plates are moving towards each other. Usually, an oceanic plate sinks below the other and it is destroyed in the subduction zone. Sediments on the sea bed between the two plates are compressed and folded to form the world’s highest mountain ranges.

The friction from the plate movement makes the rocks melt, and this produces volcanoes. Earthquakes are frequent since the ground shakes from the forced movement of rock.

3) Conservative

Two plates move against each other. This may be in the same direction but at different speeds. Stress built up causes sudden plate movements. Friction caused by rock rubbing against rock forms earthquakes.

Negative Impacts on People

The shockwaves have damaged buildings; pillars supporting bridges and roads collapse, and people are killed or injured.

Primary and Secondary Effects

Primary effects are those caused by the earthquake shock itself. Secondary effects are those that happen in the minutes, hours, and days after the earthquake.

Volcanoes and Their Negative Impacts

People living on the volcano’s slopes can be in great danger. Most dangerous volcanoes erupt suddenly without warning. People are killed by:

• Rocks, volcanic bombs, and ash, since they may rain on top of them.
• Lava flows can be so fast that people don’t have time to move.
• Poisonous gases and fumes may drift over populated areas.
• Heat may melt snow on mountain tops, which sets off mudflows that sweep houses and people away.

Warning Signs of Volcanic Eruptions

Volcanoes can give some warning signs, such as:

• Temperature increases in the crater.
• Increased amounts of steam and gases come out of the crater.
• Small earthquake shocks felt in the surrounding area.

Factors Affecting Earthquake Destruction

The size of an earthquake affects the amount of destruction and the number killed. There are other factors:

• The number of people living close to the epicenter.
• The quality of construction of buildings.
• How well prepared the people and emergency services are.