Gala University Physical Geology Lecture 2 PDF

G A L A L A U N I V E R S I T Y T H E F U T U R E S T A R T S H E R E Powered by Arizona State University Field of Basic Sciences Department of Geological Sciences T H E F U T U...

G A L A L A U N I V E R S I T Y T H E F U T U R E S T A R T S H E R E Powered by Arizona State University Field of Basic Sciences Department of Geological Sciences T H E F U T U R E S T A R T S H E R E  Field of Basic Sciences Department of Geological Sciences GES 111 Physical Geology For students from the programs of 1) Petroleum & Mining Geology, 2) Biotechnology & 3) Nanotechnology Instructor: Prof. Adel A. Surour Fall 2023  Lecture 2 Physical Geology & Geohazards  Internal vs. External Processes  How does geology affect our lives? Geology is all around us, from the sand and stones used to build the walls and roads, to the numerous minerals found in our everyday objects from laptops to smartphones, in the food we eat, in the landscape around us and their effects on our lives. Energy The majority of the electricity we use in our homes comes from fossil fuels. Fossil fuels such as coal, oil and gas are formed by the decay of living organisms from millions of years ago. Water The water we drink, the water we use to shower and the water we use to flush our toilets can come from sources above or below ground. Above ground we can use water from rivers or lakes that we can easily see but we can also find water beneath the ground. Water can sink through cracks and holes into rocks, here the water is stored in rock layers known as aquifers. This water can be reached using wells. Food and Drink The food and drink we eat depends on the soil it grows in. Soil can contain many different minerals that can affect how our food grows. The minerals present in the soil are the result of how the soil and subsoil formed. Fluoride in your toothpaste Fluoride is a naturally occurring mineral that is added to toothpaste to help protect your teeth from cavities. Calcium for your bones and teeth We know that calcium is necessary for healthy bones and teeth and we know milk and dairy products are good sources of it but where does it come from? Calcium is a mineral that can be found in the soil and this means grass contains lots of calcium too. When cows eat the grass the calcium builds up in their bodies and comes out in their milk. Minerals in our smartphones and laptops Our smartphones and laptops rely heavily on minerals such as Lithium, Cobalt and Gold. Natural Hazards The most common natural hazards all over the world are: 1) Earthquakes ​2) Landslides 3) Coastal erosion 4) Sinkholes 5) Volcanoes 6)Tsunami 7) Groundwater Flooding 1) Earthquakes Earthquakes are sudden tremors or vibrations that occur in the Earth’s crust. When tectonic plates are colliding or trying to slide past each other there is a build-up of pressure between the two plates in the Earth’s crust along what is called a fault line. This pressure is then suddenly released when the plates move at the fault line and cause a violent shaking of the earth’s surface in the form of an earthquake. Focus The point within the earth’s crust where the earthquake begins is called the focus. The focus can be tens of kilometres deep and it emits powerful shockwaves or tremors that shake the earth’s crust. As the shockwaves travel through the earth’s crust they spread out and become less powerful in much the same way as ripples in a pool spread out after a stone is thrown into the water. Epicentre The point on the earth’s surface directly above the focus is called the epicentre. The epicentre suffers the most powerful shockwaves and damage from an earthquake. Aftershocks are smaller tremors that occur after the main earthquake and can often cause weakened buildings to collapse. Seismology Seismology is the scientific study of earthquakes. The 'father of seismology' was an Irishman from Dublin called Robert Mallet. He carried out scientific studies on seismology in the mid 1800's using dynamite on Killiney Beach and is credited with inventing the words seismology and epicentre. Seismographs are instruments that are used for measuring the exact strength of an earthquake. Richter Scale The Richter Scale is used to show the strength of an earthquake and ranges from 1 to 12. Each unit on the Richter Scale is ten times more powerful than the previous one so an earthquake measuring 7 on the Richter Scale in ten times more powerful than one measuring 6. 2) Landslides Landslides occur all over the world and can cause major and destruction and loss of life in extreme circumstances. Ireland is fortunate not to be in an extreme high risk to major geohazards. Indeed, in comparison to many other countries, Ireland may be regarded as a benign environment in terms of landslide hazard. However, terrain and climate in Ireland result in landslides occurring mainly in areas with steep slopes where rock meets the surface and peat covers the terrain. 3) Coastal Erosion The power of the sea has shaped Ireland’s coast into what we can see today. Two main processes are responsible for this; erosion and deposition. Coastal erosion is the breaking down and carrying away of materials by the sea. Deposition is when material carried by the sea is deposited or left behind on the coast. Destructive Waves Coastal erosion takes place with destructive waves. These destructive waves are very high in energy and are most powerful in stormy conditions. Constructive Waves Constructive waves, on the other hand, are low energy waves that result in the build-up of material on the shoreline. 4) Sinkholes Karst landscapes are characterised by solution and voids in the bedrock and this can result in geohazards. An uneven bedrock surface, gradual ground subsidence or sudden collapse associated with subsurface voids can results in significant problems for engineering.​ 5) Volcanoes What is a Volcano? A volcano is an opening in the Earth’s crust that allows magma, ash and gasses to erupt from below the surface. It is made up of a magma chamber, a vent, a crater and a cone shaped mountain made of layers of ash and lava. Magma chamber: Magma from the Earth’s mantle collects in a large underground pool. The magma in a magma chamber is under great pressure trying to force its way upward to the surface. Vent: The magma forces its way up through the vent which is like a chimney for the volcano. There is the main vent but there can also be secondary vents on the side or flank of the volcano. These secondary vents produce secondary cones on the flank of the volcano. Crater: The crater or caldera is the bowl shaped feature on top of the volcano that the magma from the vent erupts form. What is the difference between magma and lava? Magma is molten rock below the surface of the Earth’s crust, when this molten rock reaches the surface of the earth is is then called lava. 6) Tsunami Waves A tsunami is a very large coastal wave that is most often the result of an underwater earthquake. The word tsunami comes from the Japanese meaning a ‘harbour wave’. Causes Most large tsunamis occur at convergent plate boundaries where two tectonic plates are crashing into each other. As the two plates collide one plate is forced down underneath the other. G A L A L A U N I V E R S I T Y T H E F U T U R E S T A R T S H E R E Thanks for Attention T H E F U T U R E S T A R T S H E R E