Earthquakes and Earth’s Interior Chapter 8 Earthquakes and Earth’s Interior

Section 8.1 What is an Earthquake?

What is an earthquake? An earthquake is the vibration of Earth produced by the rapid release of energy. Example: 1906 San Francisco Earthquake. Earthquakes usually occur when rocks under stress suddenly shift along a fault. Stress: A force that can change the size and shape of rocks. Fault: Fractures in the Earth where movement occurred. The area along a fault where slippage first occurs is called the focus of an earthquake. The point on the earth’s surface directly above the focus is called the epicenter. When an earthquake occurs, seismic waves radiate outward in all directions from the focus.

What is an earthquake?

A fault is A place on Earth where earthquakes cannot occur. A fracture in the Earth where movement has occurred. The place on Earth’s surface where structures move during an earthquake. Another name for an earthquake.

An earthquake’s epicenter is The place on the surface directly above the focus. A spot halfway between the focus and the surface. The spot below the focus. Any spot along the nearest fault.

When an earthquake occurs, energy radiates in all directions from its source, which is called the Epicenter. Focus. Fault. Seismic Center.

Earthquakes are usually associated with Violent weather. Faults. Large cities. The east coast of North America.

What is an earthquake? Geologists explain many earthquakes by the elastic rebound hypothesis. This hypothesis states that when the stress in rocks becomes to great, they fracture, separate, and spring back to their original shape, or rebound. As they fracture and slip into new positions, rocks along a fault release energy in the form of vibrations called seismic waves.

What is an earthquake?

Which of the following causes earthquakes? Elastic Rebound. Richter Scale. Release of Heat. Frictional Heating.

The hypothesis that explains the release of energy during an earthquake is called the Richter Hypothesis. Moment Magnitude Hypothesis. Vibration Hypothesis. Elastic Rebound Hypothesis.

Most earthquakes are produced by the rapid release of which kind of energy stored in rock subjected to great forces? Chemical Thermal Elastic Mechanical

During an earthquake, the ground surface Moves only in a horizontal direction. Moves only in a vertical direction. Can move in any direction. Does not move.

What is an earthquake? This release of energy often increases the stress in other rocks along the fault, causing them to fracture and spring back. This reaction is the reason that major earthquakes are usually followed by a series of smaller tremors called aftershocks. These aftershocks are usually much weaker than the main earthquake, but they can sometimes destroy structures weakened by the main quake.

What is an earthquake? Small earthquakes called foreshocks often come before a major earthquake. These can happen days or even years before the major quake. The San Andreas Fault is the most studied fault system in the world. Studies have shown that displacement has occurred along segments that are 100 to 200-kilometers long (63 to 125-miles). Some segments move slowly, which is known as fault creep. Other segments regularly slip and produce small earthquakes. Some segments stay locked and store elastic energy for hundreds of years before they break and cause great earthquakes.

The adjustments of materials that follow a major earthquake often generate smaller earthquakes called Foreshocks. Surface waves. Aftershocks. Body waves.

Major earthquakes are sometimes preceded by smaller earthquakes called Aftershocks. Focus shocks. Surface waves. Foreshocks.

The slow continuous movement that occurs along some fault zones is referred to as Slip. Creep. Fracture. A foreshock.

Small foreshocks that precede a major earthquake occur From the day of the major earthquake to days after the earthquake. Only on the day of the major earthquake. Days or years before the major earthquake. Only on the day before the major earthquake.