Test 3 Ch. 10-12

Primary waves, also known as P-waves, are the fastest seismic waves and therefore have the highest velocities. These waves are compressional waves that travel through solids, liquids, and gases. They are the first waves to be detected during an earthquake and can move through the Earth's interior in a straight line. Primary waves have the ability to travel through both solid and liquid layers of the Earth, making them faster than secondary waves and surface waves.

The San Andreas strike-slip fault in California is the boundary between the North American and Pacific plates. This fault is characterized by horizontal movement, where the two plates slide past each other in opposite directions. The San Andreas fault is well-known for its frequent seismic activity and has been responsible for several major earthquakes in the region.

The Mercalli Scale is a scale that rates the structural damage due to an earthquake. It ranges from I to XII, with I representing minimal damage and XII representing total destruction. The scale is based on observations of the effects of an earthquake on buildings, structures, and the environment. It takes into account factors such as shaking intensity, ground rupture, and the impact on human-made structures. By assigning a rating to the observed damage, the Mercalli Scale provides a qualitative measure of the earthquake's intensity and its impact on the built environment.

The dense core of Earth is thought to consist predominantly of iron. This is based on scientific evidence such as seismic data and the Earth's magnetic field. Iron is a common element in the Earth's crust and mantle, and it is believed to have sunk to the core during the planet's formation. The high density of iron makes it the most likely candidate for the core's composition. Additionally, experiments and simulations have supported the hypothesis that iron is the primary component of Earth's core.

An earthquake is a natural phenomenon characterized by a rapid release of energy stored in deforming rocks, causing them to move and creating vibrations that propagate through the Earth. This release of energy can result in violent shaking of the ground, posing a significant environmental hazard that can cause damage to many human-made structures. Therefore, all of the given options accurately describe different aspects of an earthquake.

By observing earthquake waves, scientists have been able to study the behavior of these waves as they travel through the Earth. These waves travel at different speeds and are affected by the different layers of the Earth. By analyzing the patterns and characteristics of these waves, scientists have been able to determine that the Earth has a core, a mantle, and a crust. The way the waves refract and reflect off these layers provides evidence for the existence of these distinct layers within the Earth's structure.

The Richter scale is logarithmic, meaning that each whole number increase represents a tenfold increase in the amplitude of the seismic waves and approximately 31.6 times more energy release. Therefore, a 6.5 magnitude earthquake releases approximately 30 times more energy than a 5.5 magnitude earthquake.

Liquefaction refers to the tendency for a foundation material to lose its internal cohesion and fail mechanically during earthquake shaking. This occurs when saturated or partially saturated soil temporarily loses its strength and behaves like a liquid, leading to ground failure and potential damage to structures. Liquefaction is a common phenomenon in areas with loose, water-saturated soils, and it can have significant impacts on the stability and safety of infrastructure during seismic events.

Since the earthquake occurs directly under the South Pole, the seismic waves would travel in all directions, including towards the North Pole. However, S waves cannot pass through the liquid outer core of the Earth, so they would not be detected at the North Pole. On the other hand, P waves can travel through both solid and liquid mediums, so they would be detected at the North Pole. Therefore, the seismic station at the North Pole would receive P waves from this quake but not S waves.

Brittle deformation occurs in rocks that are colder because at lower temperatures, rocks are more rigid and less able to undergo plastic deformation. On the other hand, ductile deformation occurs at high temperature where energy is higher because at elevated temperatures, rocks become more malleable and can undergo plastic deformation without fracturing.

The core of the Earth is made of iron and nickel. This is supported by scientific evidence and studies that have been conducted on the Earth's composition. The iron-nickel core is believed to be responsible for generating the Earth's magnetic field.

Since the seismic station is located at the North Pole and the earthquake occurs directly under the South Pole, the S waves would not be able to travel through the Earth's core to reach the North Pole. However, P waves can travel through both solids and liquids, so they would be able to reach the seismic station. Therefore, the correct answer is that the seismic station would receive P waves from this quake, but no S waves would be detected.

The arrival times of P and S waves can be used to determine the distance between a seismological recording station and the earthquake source. P waves, or primary waves, are the fastest seismic waves and arrive at the recording station first. S waves, or secondary waves, are slower and arrive after the P waves. By measuring the time difference between the arrival of P and S waves, scientists can calculate the distance based on the known speed of the waves. This information is crucial for understanding the location and intensity of an earthquake.

Bedrock is the most stable foundation material during earthquake shaking because it is a solid, dense, and rigid rock that is not easily affected by ground shaking. Unlike water-saturated, unconsolidated moist soil, and sand and mud, which are more prone to liquefaction and shifting during an earthquake, bedrock provides a strong and stable base for structures, minimizing the risk of damage or collapse.

Seismic waves are vibrations that travel through the Earth's interior, and they provide valuable information about its structure and composition. By studying the behavior of seismic waves as they travel through different layers of the Earth, scientists can infer the properties of these layers, such as their density, temperature, and composition. This information helps us understand the structure of the Earth's interior, including the core, mantle, and crust. Thus, seismic waves are a crucial tool in our quest to gain knowledge about the Earth's interior.

The words "dome," "anticline," and "basin" all refer to geological formations or structures, while "thrust fault" is a type of fault in which rocks are pushed together. The other three terms describe different types of geological features, while "thrust fault" describes a specific type of fault. Therefore, "thrust fault" does not fit the pattern of the majority of words/phrases.

Plastic deformation refers to the permanent change in shape of a material without fracturing. This process occurs when the material is subjected to stress beyond its elastic limit. High temperatures facilitate plastic deformation as they increase the mobility of atoms and allow for easier movement of dislocations within the material's crystal structure. At low temperatures, the material becomes more brittle and is more likely to fracture rather than undergo plastic deformation. Medium temperatures may still allow for some plastic deformation, but high temperatures are generally more favorable for this process. Therefore, plastic deformation mainly occurs under high temperatures.

A syncline is a type of fold in rock layers where the strata dip toward the axis. In other words, the layers of rock are folded downwards, forming a U-shape. This is in contrast to an anticline, where the strata dip away from the axis. Synclines are often found in areas of compression and can be a result of tectonic forces. They are important in geological studies as they provide insights into the deformation and folding of rock layers over time.

Cooler temperatures would favor brittle deformation over plastic deformation because at lower temperatures, rocks are more likely to be rigid and less ductile. This means that they are more prone to fracturing and breaking rather than undergoing plastic deformation, which involves the rocks bending and flowing. In contrast, warmer temperatures promote plastic deformation as they increase the rocks' ductility and ability to deform without fracturing.

On a typical seismogram, surface waves will show the highest amplitudes. This is because surface waves are the slowest and most destructive seismic waves that travel along the Earth's surface. They cause the most shaking and are responsible for the majority of the damage during an earthquake. P waves and S waves, also known as body waves, travel through the Earth's interior and have lower amplitudes compared to surface waves. Therefore, surface waves exhibit the highest amplitudes on a seismogram.

The Richter magnitude scale is a measure of the energy released during an earthquake. It quantifies the seismic energy based on the amplitude of seismic waves recorded by seismographs. It does not directly measure the extent of building damage caused by the earthquake. The scale is logarithmic, meaning that each whole number increase on the Richter scale represents a tenfold increase in the amplitude of the seismic waves and approximately 31.6 times more energy release. Therefore, the Richter magnitude scale is primarily used to compare the relative size or strength of different earthquakes rather than assessing the damage they cause.

A low angle reverse fault is a type of thrust fault where the hanging wall moves up and over the footwall at a shallow angle. This type of fault is characterized by compression forces causing the rocks to deform and the hanging wall to move upward. The angle of the fault plane is less than 45 degrees, distinguishing it from a steep angle reverse fault. This fault type is commonly associated with mountain building and can result in the uplift of rock layers.

A horizontal and a vertical seismograph are used so that a full range of motion of the earthquake waves can be observed. By using both types of seismographs, we can capture the horizontal and vertical components of the seismic waves. This allows us to accurately measure the amplitude and direction of the waves, providing a comprehensive understanding of the earthquake's characteristics.

Tsunamis are characterized by their relatively small amplitudes compared to their very long wavelengths. This means that while they may not appear to be very tall or noticeable in terms of height, they can extend over a large distance and have a significant impact on coastal areas. This is why they can be particularly dangerous, as their low height may not be indicative of the destructive force they can carry.

The majority of words/phrases in the given list are natural disasters or geological events, such as tsunami, liquefaction, and seiches. However, fire does not fit this pattern as it is not a natural disaster or geological event.

The asthenosphere is located in the upper mantle. This region is characterized by its semi-fluid state, where the rock is hot and under high pressure. It lies beneath the lithosphere, which includes the crust and the uppermost part of the mantle. The asthenosphere plays a crucial role in plate tectonics, as it is the layer where convection currents occur, causing the movement of the Earth's tectonic plates.

Jointing in rocks refers to the presence of fractures or cracks that separate blocks of rock without any displacement. These fractures are roughly parallel to each other and do not show any movement or offset between the blocks. Jointing is a common characteristic in many types of rocks and can occur due to various factors such as cooling and contraction, tectonic stresses, or weathering. It provides important information about the mechanical properties and behavior of rocks, as well as their potential for fluid flow and deformation.

A transform fault is a type of fault that occurs when two tectonic plates slide past each other horizontally. This movement is known as strike-slip motion. Transform faults are commonly found at the boundaries between tectonic plates, where they accommodate the lateral movement of the plates. Unlike other types of faults, such as dip-slip or reverse faults, transform faults do not involve vertical displacement or the creation of new crust. They are characterized by the absence of significant seismic activity and are often associated with features like offset rivers and linear valleys.

When an earthquake occurs, energy radiates in all directions from its source. The term "focus" refers to the exact point within the Earth's crust where the earthquake originates. It is the location where the seismic waves start to propagate and spread outwards. The term "epicenter" refers to the point on the Earth's surface directly above the focus, where the earthquake is typically felt the strongest. The term "inertial point" and "seismic zone" are not commonly used in earthquake terminology.

The mechanism by which rocks store and eventually release energy in the form of an earthquake is called elastic rebound. This refers to the process where rocks deform and accumulate stress along a fault line until they reach their elastic limit. Once the stress exceeds this limit, the rocks snap back into their original shape, releasing the stored energy and causing an earthquake. The term "seismic rebound" is not commonly used and "fault displacement" and "stress fracture" do not specifically describe the process of energy storage and release in earthquakes.

High temperature and high confining pressure should favor folding rather than faulting because at high temperatures, rocks become more ductile and are more likely to deform plastically. Additionally, high confining pressure helps to evenly distribute the stress on the rocks, allowing them to deform more easily without fracturing. This combination of high temperature and high confining pressure promotes folding, which is a type of ductile deformation where rocks bend and fold instead of breaking along faults.

In a normal fault, the hanging wall moves up. This type of fault occurs when tensional forces cause the hanging wall to move upward relative to the footwall. The fault plane is inclined, with the hanging wall above the footwall. This movement is a result of the stretching and thinning of the Earth's crust.

The lithosphere is defined as a rigid layer of crustal and mantle material. This layer is characterized by its rigidity and is composed of both crustal and mantle rocks. It is the outermost layer of the Earth and is broken into several tectonic plates. These plates float on the semi-fluid asthenosphere beneath them. The lithosphere plays a crucial role in plate tectonics and is responsible for the formation of mountains, earthquakes, and volcanic activity.

A strike-slip fault is characterized by horizontal movements of the two blocks, with little to no vertical movement. In this type of fault, the blocks slide past each other horizontally, parallel to the fault line. This is different from a dip-slip fault, where the movement is primarily vertical, and from oblique slip faults, where there is a combination of both vertical and horizontal movements. Stick-slip is not a type of fault, but rather a phenomenon that occurs when friction causes the blocks to stick and accumulate stress before eventually slipping and releasing energy in the form of an earthquake.

The correct answer is Moho. The Moho, also known as the Mohorovičić discontinuity, is the boundary between the Earth's crust and mantle. It was named after the Croatian seismologist Andrija Mohorovičić, who discovered this boundary in 1909. The Moho is characterized by a significant increase in seismic wave velocity, marking the transition from the solid crust to the more ductile and flowing mantle beneath.

The correct answer suggests that the diameter of Earth's core and the nature of the outer core were discovered through the analysis of the P-wave and S-wave shadow zones. This means that scientists observed how seismic waves travel through the Earth and noticed differences in their paths and velocities, which provided insights into the structure and composition of the core. By studying these shadow zones, scientists were able to infer the size and characteristics of Earth's core.

The average composition of the continental crust is most similar to granite. Granite is a common type of rock found in the continental crust and is composed mainly of quartz, feldspar, and mica. Basalt, on the other hand, is a type of rock found in the oceanic crust and has a different composition. Peridotite is a type of rock found in the Earth's mantle and is not part of the continental crust. Iron, while present in the Earth's crust, is not the main component of the continental crust.

A horst is an uplifted block bounded by two normal faults. Normal faults occur when the hanging wall moves downward relative to the footwall, resulting in the block being uplifted. In the case of a horst, two normal faults are present on either side of the block, causing it to be uplifted. This geological feature is commonly found in areas of tectonic activity, where tensional forces cause the crust to stretch and create normal faults.

The correct answer is "An elongate dome cored by Proterozoic igneous and metamorphic rocks." This means that the Black Hills region in South Dakota is characterized by a dome-shaped geological structure composed of igneous and metamorphic rocks from the Proterozoic era. The term "cored" implies that these rocks form the central part or core of the dome.

A formation is a recognizable, mappable, rock unit of known age. Formations are distinct layers of rock that have similar characteristics and are typically named based on the location where they were first identified. They can be mapped and correlated across different areas, allowing geologists to understand the geological history and make predictions about the rock layers in a particular region. Formations are an important tool in stratigraphy, the study of rock layers and their relationships, and they help to establish a chronological framework for understanding Earth's history.

A deeply eroded structural basin would exhibit strata oriented in roughly circular outcrop patterns. This is because erosion would have removed the outer layers of the basin, leaving behind the older, more resistant strata in the center. As a result, the remaining strata would appear in a circular pattern when viewed from above.

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In a normal fault, the hanging wall block above an inclined fault plane moves downward relative to the other block. This is because normal faults occur when the hanging wall block drops down relative to the footwall block due to tensional forces pulling the blocks apart. As a result, the hanging wall block moves downward while the footwall block remains relatively stationary or moves upward.

The correct answer is that a sliver of continent west of the fault is moving northward with the Pacific plate. This means that the tectonic movement at the San Andreas Fault is causing a portion of the landmass on the west side of the fault to move in a northward direction along with the Pacific plate. This movement is a result of the relative motion between the Pacific plate and the North American plate, which is responsible for the formation and activity of the San Andreas Fault.

The majority of words/phrases in the given list are types of faults that occur in the Earth's crust. Normal fault, reverse fault, and thrust fault are all types of faults that involve the movement of rock layers along a fault plane. However, a strike-slip fault is a different type of fault where the rocks on either side of the fault plane move horizontally past each other. Therefore, strike-slip fault does not fit the pattern of the other three types of faults.

Seamounts are underwater mountains that are formed by volcanic activity on the ocean floor. They are not limited to the Pacific Ocean basin, as they can be found in various ocean basins around the world. Seamounts are not oceanic trenches, which are deep, narrow depressions in the ocean floor. They are also not submarine canyons found near Australia. The correct answer is that seamounts are volcanoes that form on the ocean floor.

The given statement "oceanic crust is enriched in potassium, sodium, and silicon" is not true. Oceanic crust is actually enriched in iron, magnesium, and calcium, while continental crust is enriched in potassium, sodium, and silicon. This is due to the differences in the composition and formation of these two types of crust. Continental crust is primarily made up of granite, which is rich in potassium, sodium, and silicon, while oceanic crust is mainly composed of basalt, which is rich in iron, magnesium, and calcium.

The P-wave shadow zone is largely the result of refraction of P waves crossing the mantle-outer core boundary. P waves are seismic waves that can travel through both solid and liquid materials. However, when they encounter a boundary between different materials, they can change direction or speed, a phenomenon known as refraction. In the case of the mantle-outer core boundary, the P waves undergo refraction, causing them to bend away from the shadow zone. This results in a region on the opposite side of the Earth from the earthquake where P waves are not detected, known as the P-wave shadow zone.

Oceanic ridges are elevated compared to the surrounding ocean floor because the newly formed lithosphere is hotter and therefore less dense than the surrounding rocks. As the lithosphere is being created at the oceanic ridges through seafloor spreading, it is still hot and less dense compared to the older lithosphere. This buoyant, less dense lithosphere rises and pushes up the overlying rocks, resulting in the elevation of the oceanic ridges.

Basins are large circular downwarped structures. They are characterized by their concave shape, with the center being lower than the surrounding areas. Basins often form due to tectonic forces, such as the subsidence of crustal blocks or the collapse of volcanic calderas. They can also be formed by the erosion of softer rocks, creating a depression in the landscape. Basins are important geological features as they can accumulate sediments and form reservoirs for water, oil, and gas.