Understanding Earthquakes and Their Causes

Study Notes

What is an Earthquake?

Millions of earthquakes happen annually, but most are too small to be felt.
The USGS reports approximately 20 earthquakes annually in the United States.
Earthquakes originate from the movement of tectonic plates within the Earth's upper mantle and crust.
Plate movement occurs in three primary ways: subduction, lateral sliding, and spreading.
Subduction involves plates colliding, with one sliding beneath the other, often forming mountains or causing plate destruction.
Lateral sliding happens when plates move alongside each other, creating frictional forces.
Spreading occurs when plates move apart, leading to the ascent of molten rock that cools and solidifies, forming new crust.
The Pacific Ring of Fire is the primary source of approximately 90% of earthquakes, and is also an area of numerous active volcanoes.

Measuring Earthquakes

Earthquakes can cause significant surface damage and trigger secondary disasters, including avalanches, landslides, and tsunamis.
The point on the Earth's surface directly above the earthquake's origin is the epicenter.
Seismographs measure and detect the vibrations generated by earthquakes.
Earthquake magnitude is a numerical measurement of strength. Moderate earthquakes register around 5.5, while major earthquakes exceed 8.0.
Earthquakes below magnitude 2.5 are typically not felt but can be recorded.

Seismologists

Seismologists are scientists who study earthquakes.
A homemade seismograph can be constructed to illustrate earthquake dynamics.
The home seismograph experiment involves shaking a cardboard box and observing how a marker attached to a string mimics the movement of a seismograph during an earthquake.

Description

This quiz explores the phenomenon of earthquakes, including their causes, how they are measured, and their impact on the Earth's surface. Learn about tectonic plate movements and the significance of the Pacific Ocean's Ring of Fire in earthquake occurrence. Test your knowledge of these natural disasters and their characteristics.