Chapter 10 Vocabulary Quiz (Earthquakes)

An aftershock refers to a smaller earthquake that occurs after a larger earthquake, typically in the same area. It is caused by the adjustment of the Earth's crust following the main earthquake. Aftershocks can continue for days, weeks, or even months after the initial earthquake, gradually decreasing in frequency and intensity. These smaller tremors are considered aftershocks because they are directly related to the main seismic event and are a natural consequence of the stress redistribution in the Earth's crust.

An earthquake refers to the shaking of the Earth's crust due to the release of energy. This release of energy can occur due to various reasons, such as tectonic plate movements, volcanic activity, or even human-induced causes like mining or reservoir-induced seismicity. The sudden release of energy causes vibrations that propagate through the Earth, resulting in the shaking and trembling that we associate with earthquakes. These seismic events can vary in magnitude and can have significant impacts on the affected regions, including damage to infrastructure, loss of lives, and changes in the landscape.

The epicenter is the point on the Earth's surface directly above the focus of an earthquake. When an earthquake occurs, the energy is released from the focus, which is the point within the Earth where the earthquake originates. The epicenter is the location on the surface that is closest to the focus and experiences the highest levels of shaking. It is the point where the seismic waves first reach the surface, causing the most damage and where scientists typically measure and record earthquake data.

A tsunami is a large ocean wave that is caused by an underwater earthquake, landslide, or volcanic eruption. These events can displace a significant amount of water, creating powerful waves that can travel across the ocean at high speeds. Tsunamis can cause widespread destruction and loss of life when they reach coastal areas. They are different from regular ocean waves because they have much longer wavelengths and can travel across the entire ocean basin.

A seismogram is a recording of an earthquake made by a seismograph. It is a graphical representation that shows the intensity and duration of the seismic waves produced by the earthquake. The seismograph detects and measures the ground motion caused by the earthquake and records it on a seismogram. This allows scientists to analyze and study the characteristics of the earthquake, such as its magnitude, location, and depth.

The focus refers to the point within the Earth where an earthquake originates. It is the exact location where the first movement occurs, generating seismic waves that propagate outward. The focus can be at varying depths within the Earth's crust, and its size and intensity determine the magnitude and impact of the earthquake on the surface.

Body waves are waves of energy that travel through the interior of the Earth, originating from the focus of an earthquake. These waves can be further classified into two types: P-waves and S-waves. P-waves, also known as primary waves, are compressional waves that travel faster and can pass through solids, liquids, and gases. S-waves, also known as secondary waves, are shear waves that travel slower and can only pass through solids. Both P-waves and S-waves are examples of body waves, as they travel through the body of the Earth rather than on its surface.

A seismograph is an instrument used to detect and record seismic waves caused by earthquakes. It consists of a stationary base and a suspended mass, which remains relatively motionless during normal conditions. When an earthquake occurs, the ground shakes, causing the base to move while the suspended mass remains in its original position due to inertia. This relative motion is recorded by a pen attached to the suspended mass, creating a graphical representation called a seismogram. By analyzing the seismogram, scientists can determine various properties of the earthquake, such as its intensity, duration, and location.

P waves, also known as primary waves, are a type of body wave that travel through the Earth and cause the rock materials to be squeezed and stretched as they pass through. These waves are the fastest seismic waves and can travel through both solids and liquids. P waves are characterized by their compressional motion, where particles move back and forth in the same direction as the wave's propagation. They are the first waves to be detected by seismographs during an earthquake and provide valuable information about the Earth's interior.

S waves, also known as secondary waves, cause particles of rock to travel at right angles to each other. These waves are responsible for the side-to-side and up-and-down motion during an earthquake. Unlike P waves, which are compressional waves that travel through solids, liquids, and gases, S waves can only travel through solids. Their ability to move particles perpendicular to the direction of wave propagation makes them slower than P waves and causes them to arrive at seismic stations after the initial P wave.

Magnitude is a measure of the amount of energy released during an earthquake. It is a numerical value that represents the size or strength of an earthquake. The magnitude scale is logarithmic, meaning that each whole number increase on the scale represents a tenfold increase in the amplitude of the seismic waves. Therefore, a higher magnitude indicates a more powerful earthquake with greater energy release.

A seismic gap refers to an area along a seismically active fault where no earthquake activity has occurred for a significant period of time. This can be explained by the concept of elastic strain accumulation. As tectonic plates slowly move and build up stress along a fault line, eventually the stress becomes too great and is released in the form of an earthquake. However, in a seismic gap, the stress has not been released yet, indicating that a significant earthquake is likely to occur in the future. This makes seismic gaps important for earthquake forecasting and understanding the seismic activity in a region.

A fault is a break in the lithosphere where movement has occurred. It is a fracture in the Earth's crust where rocks on either side have moved relative to each other. Faults can occur due to tectonic forces, such as when two plates collide or slide past each other. The movement along a fault can result in earthquakes, as the stress built up along the fault is released suddenly. Faults are important in understanding the Earth's tectonic activity and studying the distribution of earthquakes.

Surface waves are a type of seismic waves that travel along the Earth's surface. They are slower than body waves and cause the most damage during an earthquake. Surface waves can be divided into two types: Love waves and Rayleigh waves. Love waves move in a side-to-side motion, while Rayleigh waves move in an elliptical, rolling motion. These waves are responsible for the shaking and destruction experienced during an earthquake.

Liquefaction refers to a temporary state in which loose soil and rock materials behave like a liquid. This phenomenon usually occurs during or after an earthquake when the ground experiences intense shaking. The shaking causes the soil particles to lose contact with each other, resulting in a loss of strength and stiffness. As a result, the soil behaves like a liquid, which can lead to the sinking, tilting, or sliding of structures built on top of it. Liquefaction can cause significant damage to buildings, infrastructure, and other human-made structures.