YOU WERE LOOKING FOR: Geology Test Answers
What are the major types of faults? Normal Faults: Vertical movement, footwall goes up, tension, causes lengthening. Reverse Fault: Vertical movement, footwall goes down, compression, causes shortening. What is the difference between an anticline...
Particle move parallel to direction of wave travel. Move through solid, liquid or gas. S Wave secondary sheer - shear waves, slower than p waves, second to arrive at seismic station, particles move perpendicular to direction of wave travel, move...
Increased it by loading Earth's crust through construction of large reservoirs; by disposal of liquid waste in deep disposal wells, which raises fluid pressure in rocks and causes movement along fractures; and by setting off underground nuclear explosions. What are somee of the major effects of earthquakes? They include violent ground motion accompanied by fracturing, which may shear or collapse large building, bridges, dams, tunnels, and other structures.
Other effects include liquefaction, landslides, fires, and tsunamis. What are some of the precursory phenomena likely to assist us in predicting earthquakes? Based on previous patterns and frequency of earthquakes as well as by monitoring the deformaation of land, the release of radon gas, and existing seismic gaps. A potential problem of predicting earthquakes is that their pattern of occurence isoften variable, with clusterring of events seperated by longer periods of time with reduced activity. What are the major goals of earthquake hazard reduction programs? Includes recognition of active faults and Earth materials sessitive to shaking and development of improved ways to predict, control, and adjust to earthquakes, including designing features to withstand them better. Education of public. Modified Mercalli - the measure of the intensity of an earthquake, based on the severity of shaking as reported by observers and varies with proximity to the epicenter. Richter - shake maps based on a dense network of seismographs can quickly show areas where potentially damaging shaking occurs.
What is viscosity, and what determines it? Viscosity is the runniness of lava. Low viscosity- thin and runny High Viscosity- thick and pasty, doesn't flow far. Viscosity is influenes by the temperature and composition. List the major types of volcano and the types of magma associated with each. List the major types of volcano and their eruption style. Why do they erupt the way they do? Activity of volcanoes due to silica content and viscosity.
Shapes of volcanoes are due to different viscosities. Shield- Common rock type is basalt an characteerized by nonexplosive lava flows. Composit or Strato- composed of andesite rock and characterised by explosive eruptions and lava flows. Basaltic lava- dark, low viscosity, very runny. Cinder cone - vent where lava comes out and solidifies in air. Caldera - completly exploded, left with whole in ground.
Domes - composed of rhyolite rock and highly explosive. Differenciate between ash falls, lateral blasts, and ash flows. Pyroclastic hazards include volcanic ash falls, which may cover large areas with carpets of ash; ash flows, or hot avalanches which move fast down the side of a volcano, and lateral blasts which can be very destructive. What is the relationship between plate tectonics and volcanoes? Directly, most volcanoes are located at plate boundaries, where magma is produced as spreading or sinking plates intereract with other Earth material.
How do lava tubes help move magma far from the erupting vents? What is the relationship between the Hawaiin Islands and the hot spot below the big island of Hawaii? Why are caldera eruptions so dangerous? They are violent, but rare, present a danger for millions of years. List the primary and secondary effects of volcanic eruptions. What are some of the methos that have been attempted to control lava flows? Hydraulic chilling and the construction of walls have been used in attempts to control lava flows. How are volcanic eruptions able to produce gigantic mmudflows? Mudflows are generated when melting snow and ice or percipitation mixes with volcanic ash.
Devastating What are some of the possible methods of forecasting volcanic eruptions? Monitoring of seismic activity, thermla, magnetic, and hydrologic properties, and topographic changes, with ocmbined knowlege of the recent geolgic history of volcanoes results in forecasting of activity. Forecasting has generally been acurate in Hawaii and the Phillipeans. What are the main ways that materials on a slope may fail? Classify: Material and motion Material- rock, earth, debri Motion movement slide plane transitional: along a plane or slide vs.
What is the safety factor, and how is it defined? Is the ratio of resisting forces to driving forces; a ratio greater than one means that the slope is stable; a ratio less than 1 indicates potential slope failure. Differenciate between rotational slide slumps and translational slides and shallow slips. Transitional slides occur along a plane. Rotational occur on a curved escarpment or they slump.
Very low grade regional metamorphism Mica-garnet schist A rock that is rich in aluminum, which includes most clay-bearing rocks. Medium-grade regional metamorphism A rock enriched in ferromagnesian minerals, such as basalt. Medium- to high-grade regional metamorphism. Marble Regional or contact metamorphism. Chapter 8 1. Xenoliths of basalt within a granite must be older than the granite according to the principle of inclusions. A useful index fossil must have survived for a relatively short period e. William Smith was familiar with the different diagnostic fossils of the rocks of England and Wales and was able to use them to identify rocks of different ages.
The last age of the Cretaceous is the Maastrichtian Chapter 9 1. P-waves can pass through a liquid and travel approximately twice as fast as S-waves which cannot pass through a liquid. P-wave velocity decreases at the core-mantle boundary because the outer core is liquid. The mantle gets increasingly dense and strong with depth because of the increasing pressure. The key evidence for mantle convection is that the rate of temperature increase within the mantle is less than expected and this can only be explained by a mantle that is mixing by convection.
The mechanism for convection is the transfer of heat from the core to the mantle. The isostatic relationship between the crust and the mantle is dependent on the plastic nature of the mantle. In the area of the Rocky Mountains the crust is thickened and pushed down into the mantle. In Saskatchewan the crust is thinner and does not extend as far into the mantle. During the Pleistocene glaciation British Columbia was pushed down by glacial ice and mantle rock flowed slowly out beneath the ocean floor.
Now that the land area is rebounding, that mantle rock is flowing back and the offshore areas are subsiding. Chapter 10 1. The evidence used by Wegener to support his idea of moving continents included matching continental shapes and geological features on either side of the Atlantic; common terrestrial fossils in South America, Africa, Australia, and India; and data on the rate of separation between Greenland and Europe. In the late 19th century the trans-Atlantic paleontological matchups were explained by assuming that there must have been land bridges between the continents at some time in the past, or that terrestrial organisms had floated across the ocean on logs. Continental crust is lighter than oceanic crust and cannot sink low enough into the mantle to become an ocean although this can happen over limited areas, and commonly does happen along coastal areas of continental plates.
Prior to , ocean depths were measured by dropping a weighted line over the side of ship. Echo sounding techniques were developed at around that time and that greatly facilitated the measurement of ocean depths. Temperature increases quite rapidly with depth in the crust, but much less so in the mantle, and this implies mantle convection. Paleomagnetic studies showed that old rocks on the continents had different pole positions than they do today, and also that they were progressively more different with time past. This implied either that the poles had moved or that the continents had moved. It was also found that the apparent polar wandering paths for different continents were different, and this supported the concept that the continents had moved.
The trenches associated with subductions zones are the deepest parts of the oceans. It was and still is assumed that high heat flow exists where mantle convection cells are moving hot rock from the lower mantle toward the surface, and that low heat flow exists where there is downward movement of mantle rock. Earthquakes are consistently shallow and relatively small at ocean ridges. At ocean trenches earthquakes get increasingly deep in the direction that the subducting plate is moving. The earthquakes near to surface can be very large, while those at depth tend to be small. In the Hess model new crust was formed at ocean ridges and then was consumed back into the mantle at the trenches. The spreading ridge is shown as a yellow line. A mantle plume is a column of hot rock not magma that ascends toward the surface from the lower mantle. It is hypothesized that mantle plumes ascend as much as 10 times faster than the rate of mantle convection.
In this case there is no faulting, and it is known as a fracture zone. Tectonic plates are made up of crust and the lithospheric rigid part of the underlying mantle. The mantle part ensures that the very different oceanic and continental crust sections of a plate can act as one unit. A mantle plume beneath a continent can cause the crust to form a dome which might eventually split open. Several mantle plumes along a line within a continent could lead to rifting. Subduction does not take place at a continent-continent convergent zone because neither plate is dense enough to sink into the mantle. The divergent boundaries are blue, the convergent boundaries are black with teeth on them, and the transform boundaries are red. The motion directions are shown with black arrows see map for names of plates.
The sense of motion on the Queen Charlotte Fault is shown with red arrows. Continental rifting is taking place along the East Africa Rift, and sea floor has recently been created in the Red Sea and also in the Gulf of California. Over the next 50 million years California is likely to split away from the rest of North America along the San Andreas Fault and then move north toward Alaska. The accumulation of sediment at a passive ocean-continent boundary will lead to the depression of the lithosphere and could eventually result in the separation of the oceanic and continental parts of the plate and the beginning of subduction. Chapter 11 1. An earthquake is the shaking caused by the release of energy that takes place when rocks under stress within Earth break and then the two sides slide past each other. Rocks under stress will deform elastically until they reach the point where the stored elastic energy exceeds the rock strength.
At that point the rock breaks and an earthquake is produced. The rupture surface is the surface over which there is displacement of rock during an earthquake. The magnitude of an earthquake is proportional to the area of the rupture surface and the average amount of displacement over that surface. An aftershock is any earthquake that is considered to have been caused by a previous earthquake as a result of the transfer of stress from the original earthquake. Episodic slip on the middle part of the Cascadia subduction zone decreases stress within that area, but some of that stress is transferred to the locked zone up dip along the plate boundary, there increasing the level of stress on the locked part. Magnitude is the amount of energy released by an earthquake. Each earthquake has only one magnitude, although there are different ways of measuring it, and they may give slightly different results. Intensity is a measure of the amount of damage done or what people felt.
Intensity varies depending on the distance to the epicentre and the type of rock or sediment underlying an area. An M7. The map shows a subduction boundary. The depth of earthquakes increases inshore to the east from the location of the subduction zone. The dash-dot line shows approximately where the plate boundary is situated. The plate on the left Nazca Plate is moving east and the one on the right South America Plate is moving west. This is the eastern coast of South America around Peru and Chile. Both divergent and transform boundaries are associated with mid-ocean ridges.
Most earthquakes take place on the transform boundaries. Unconsolidated sediments, especially if they are saturated with water, can lose strength when subjected to earthquake shaking. This can cause buildings to subside or tilt. Unconsolidated sediments can also amplify the vibrations of an earthquake. Gas lines and electrical transmission wires are typically damaged during an earthquake, and this can lead to serious fires. A large subduction earthquake greater than M7. The Parkfield earthquake showed that we cannot rely on foreshocks to predict earthquakes, or on any of the many other parameters that were being carefully measured around Parkfield in the years leading up to the quake. We should know about the history of past large earthquakes, the typical locations of small earthquakes, the types of geological materials beneath the surface especially soft water-saturated sediments , the types of infrastructure that is present, and the various ways that people can be evacuated from an area or assistance can be brought in.
Forecasting involves estimating the risk of an earthquake happening in a region within a period of time usually expressed in decades. Prediction involves stating that an earthquake is likely to happen at a certain location on a specific day or month or year in the future. With our current state of knowledge of earthquakes, prediction is not possible. Chapter 12 1. Convergent plate boundaries are the most likely to contribute to compression, divergent boundaries to extension, and transform boundaries to shearing, however all of these stress regimes can exist at any one of these boundaries. When elastic strain takes place the rock can rebound to its original shape.
When there is plastic strain the rock will be permanently deformed. Stronger rocks are more likely than weaker ones to deform elastically. Rock that is hot is more likely to deform plastically. Clay-bearing rocks are more likely to deform plastically when they are wet. If stress is applied quickly, the rock is more likely to break than if it is applied slowly. The axial planes are shown with dashed red lines. Volcanic rocks cool quickly at surface and the resulting reduction in volume can easily lead to fracturing. In a normal fault the rock above the fault moves down with respect to the lower rock. This normally indicates extension. In a reverse fault the rock above the fault is pushed up, which indicates compression. Most faults near transform boundaries are strike-slip faults, meaning that there is horizontal motion along the fault.
Chapter 13 1. A trellis drainage pattern typically forms on sedimentary rock that has been tilted and eroded 4. Many of the streams in the southwestern part of Vancouver Island flow to the ocean as waterfalls because the land has been uplifted relative to sea level over the past several thousand years. The fastest water flow on a straight stretch of a stream will be in the middle of the stream near the surface.
Kamal Omosanya Time Allowed: 3hrsGeneral instructions: 1 All answers must be written in the space provided and turned in at the end of the exam. Section A All all questions in this section. How would you explain the differences between thrust fault and Reverse faults? Are their kinematics in any way similar to Normal faulting and Strike Slip? In what way has the knowledge of fault kinematics and dynamics influence the field of Plate Tectonics. Using the well data provided below, plot a lithology section through each of the borehole in Fig 1. Attempt a genetic and geometrical classification of the structures. Based on your knowledge of the anatomy of folds, classify folds using 3D diagrams. Question: Geological events are predictable, and their effects can be minimised when fully understood.
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