Understanding Earthquakes

Study Notes

Occur when there is a sudden release of energy in the Earth's lithosphere, usually at the boundary between two tectonic plates
This energy release creates seismic waves that can cause the ground to shake, sometimes violently
Earthquakes can be classified into three types:
- Tectonic earthquakes: result from the movement of tectonic plates
- Volcanic earthquakes: result from volcanic activity
- Collapse earthquakes: result from the collapse of underground caverns or voids

Areas where two or more tectonic plates meet and interact
There are three types of plate boundaries:
1. Divergent boundaries: where two plates are moving apart, new crust is formed, and magma rises to the surface
2. Convergent boundaries: where two plates are moving towards each other, resulting in subduction or collision
3. Transform boundaries: where two plates are sliding past each other horizontally, without creating or destroying crust

The theory that the continents have moved over time and were once joined together in a single supercontinent
Evidence for continental drift includes:
- Fit of the continents: the continents fit together like a puzzle
- Similarity of rock formations: similar rock formations are found on different continents
- Fossil evidence: fossils of the same age and species are found on different continents

Occurs when magma from the Earth's interior rises to the surface, resulting in eruptions
Volcanic activity is often associated with plate boundaries, particularly at:
- Subduction zones: where one plate is being pushed beneath another
- Divergent boundaries: where two plates are moving apart
Types of volcanic activity:
- Shield volcanoes: gently sloping volcanoes with a broad base
- Stratovolcanoes: tall, conical volcanoes with a narrow base

The process by which new oceanic crust is created at mid-ocean ridges
Occurs when magma rises to the surface and solidifies, pushing the older crust apart
Evidence for seafloor spreading includes:
- Magnetic striping: rocks on either side of a mid-ocean ridge have alternating magnetic polarity
- Age of the oceanic crust: rocks on the ocean floor get progressively older with distance from the mid-ocean ridge

Sudden release of energy in the Earth's lithosphere occurs at the boundary between two tectonic plates
Energy release creates seismic waves, causing the ground to shake
Three types of earthquakes: tectonic, volcanic, and collapse

Areas where two or more tectonic plates meet and interact
Three types of plate boundaries:
- Divergent: plates moving apart, new crust formed, and magma rises to the surface
- Convergent: plates moving towards each other, resulting in subduction or collision
- Transform: plates sliding past each other horizontally, without creating or destroying crust

Theory that continents have moved over time and were once joined together in a single supercontinent
Evidence for continental drift:
- Fit of the continents: they fit together like a puzzle
- Similarity of rock formations: similar rock formations on different continents
- Fossil evidence: fossils of the same age and species on different continents

Occurs when magma from the Earth's interior rises to the surface, resulting in eruptions
Often associated with plate boundaries, particularly at:
- Subduction zones: one plate being pushed beneath another
- Divergent boundaries: plates moving apart
Two types of volcanic activity:
- Shield volcanoes: gently sloping with a broad base
- Stratovolcanoes: tall, conical with a narrow base

Process by which new oceanic crust is created at mid-ocean ridges
Occurs when magma rises to the surface and solidifies, pushing older crust apart
Evidence for seafloor spreading:
- Magnetic striping: rocks on either side of a mid-ocean ridge have alternating magnetic polarity
- Age of the oceanic crust: rocks on the ocean floor get progressively older with distance from the mid-ocean ridge