Physical Science Module 6

A fault is the correct answer because it refers to the boundary between two sections of rock that can move relative to one another. Faults occur due to the movement and displacement of the Earth's tectonic plates, resulting in earthquakes and the formation of various landforms. This term is commonly used in geology to describe the fractures or breaks in the Earth's crust where rocks on either side have moved horizontally, vertically, or laterally.

The correct answer is Dynamo Theory & Rapid-Decay Theory. Dynamo Theory suggests that the earth's magnetic field is generated by the motion of molten iron in its outer core. This motion creates electric currents, which in turn create the magnetic field. Rapid-Decay Theory, on the other hand, proposes that the earth's magnetic field is gradually weakening and will eventually reverse its polarity. This theory is based on the observation that the strength of the magnetic field has been decreasing over time.

Sedimentary rock is formed when sediments are cemented together through chemical reactions, resulting in a hardened rock. Sediments are typically made up of fragments of other rocks, minerals, and organic materials that have been weathered and eroded. Over time, these sediments accumulate and are compacted under pressure, causing them to solidify into sedimentary rock. This type of rock is often found in layers or strata and can contain fossils, providing valuable information about Earth's history.

Plastic rock refers to a type of rock that exhibits properties between those of a liquid and a solid. This means that it can deform and flow like a liquid under certain conditions, but also retain its shape like a solid. The term "plastic" in this context does not refer to the material commonly known as plastic, but rather to the rock's ability to undergo plastic deformation. This behavior is often observed in certain types of metamorphic rocks, such as schist or gneiss, which can be easily molded or bent without breaking.

The earth's magnetic field is caused by electrical flow in the core. The core of the earth is made up of molten iron and nickel, which creates a flow of electric current due to the movement of these metallic elements. This electrical flow generates a magnetic field around the earth, which is essential for protecting the planet from harmful solar radiation and for navigation purposes. The flow of electric current in the core is influenced by various factors, including the rotation of the earth and the convection currents within the core.

Scientists have observed seismic waves in order to learn about Earth's interior. Seismic waves are vibrations that travel through the Earth's layers during an earthquake. By studying the behavior of these waves, scientists can gather information about the composition, density, and structure of the Earth's interior. Seismic waves help scientists understand the different layers of the Earth, such as the crust, mantle, and core, and provide valuable insights into processes like plate tectonics and the formation of earthquakes.

Pangaea is the correct answer because many scientists believe that all the continents were once connected as a single landmass called Pangaea. This theory is supported by the matching shapes of the continents' coastlines, similarities in geological formations, and the distribution of fossils across different continents. Pangaea started to break apart around 200 million years ago, eventually forming the continents we know today.

The point on the surface of the earth directly above an earthquake's focus is called the epicenter. This is the location where the seismic waves generated by the earthquake reach the surface first. It is typically the area that experiences the greatest shaking and damage. By studying the distribution of earthquakes and their epicenters, scientists can better understand the underlying faults and tectonic activity in a region.

If a region of the earth has a lot of volcanic activity, it is expected to have volcanic and domed mountains. Volcanic mountains are formed by the accumulation of volcanic materials such as lava, ash, and pyroclastic debris. These mountains are typically steep and have a conical shape. Domed mountains, on the other hand, are formed by the uplift of large areas of rock due to the intrusion of magma beneath the Earth's surface. They have a rounded shape and are often associated with volcanic activity. Therefore, in a region with significant volcanic activity, it is reasonable to expect the presence of both volcanic and domed mountains.

The earth's magnetic field plays a vital role in protecting our planet from harmful cosmic rays emitted by the sun. These cosmic rays consist of high-energy particles that can be detrimental to life on Earth, causing genetic mutations and increasing the risk of cancer. The magnetic field acts as a shield, deflecting and trapping most of these cosmic rays, preventing them from reaching the surface. This protection is crucial for the preservation of life on our planet.

The region which is very near a boundary between two plates is more likely to have the greatest earthquake activity. Earthquakes occur when there is a release of energy along fault lines, which are often found near plate boundaries. The movement and interaction of tectonic plates at these boundaries create more stress and friction, leading to a higher likelihood of earthquakes. In contrast, the region near the middle of a plate experiences less movement and interaction between plates, resulting in lower earthquake activity.

The Rapid-Decay Theory is the most scientifically valid theory because it suggests that something is decaying quickly. This implies that there is a process of rapid deterioration or breakdown occurring. In a scientific context, theories are considered valid when they are supported by evidence and can be tested and replicated. Therefore, the Rapid-Decay Theory aligns with the scientific method by proposing a phenomenon that can be observed and studied.

The Moho, also known as the Mohorovičić discontinuity, is a boundary between the Earth's crust and mantle. It marks the transition from the solid, rigid crust to the semi-solid, ductile mantle. Therefore, the correct answer is Crust/Mantle.

A powerful deep-water ocean current carving out the trench over thousands of years is not the most likely cause because sonar measurements would not detect the movement caused by a current. The Soviet's submarine torpedoing the area during testing is not a likely cause because it would not result in a deep trench. Plate collision causing both plates to buckle is also not the most likely cause as it would result in a mountain range rather than a trench. Therefore, the most likely cause is plate separation, which would cause the plates to move away from each other and create a trench.

The Richter scale is logarithmic, meaning that each whole number increase on the scale represents a tenfold increase in the amplitude of the seismic waves and approximately 31.6 times more energy released. Therefore, if the original earthquake measures 6 on the Richter scale and the aftershock measures 4, the original earthquake released 10^2 times more energy than the aftershock. 10^2 is equal to 1,024, so the correct answer is that the original earthquake was 1,024 times more energetic than the aftershock.