Inner Earth, Magmatism, and Metamorphism Handout PDF

**LESSON 2: INNER HEAT AND FORMATION OF MAGMA** **EARTH'S INTERNAL HEAT** Heat energy plays a vital role in our planet. It is one of the extreme factors in what makes the world livable. If you think of a volcano, you know Earth must be hot inside. The heat inside of our planet moves continents, bu...

**LESSON 2: INNER HEAT AND FORMATION OF MAGMA** **EARTH'S INTERNAL HEAT** Heat energy plays a vital role in our planet. It is one of the extreme factors in what makes the world livable. If you think of a volcano, you know Earth must be hot inside. The heat inside of our planet moves continents, build mountains and causes earthquakes, but where does all this heat inside the earth come from? Sources of heat in our planet can be identified as: **1. Primordial heat** - During the early formation of the Earth, the internal heat energy that gradually gathered together by means of dispersion in the planet during its few million years of evolution is called ***Primordial heat***. - The major contribution of this internal heat is the **accretional energy** -- the energy deposited during the early formation of a planet. **2. Radiogenic heat**. - the **thermal energy** released as a result of spontaneous nuclear disintegration is called ***Radiogenic Heat***. - It involves the disintegration of natural radioactive elements inside the earth -- like Uranium, Thorium and Potassium. - Uranium, with atomic number of 92 is a special kind of element because when it decays, heat (radiogenic) is produced. **HOW MAGMA IS FORMED?** What is Magma? **Magma** is composed of semi-liquid hot molten rocks located beneath the Earth, specifically in the melted mantle rock and oceanic plate. This molten state, when solidified, creates igneous rocks found on the surface of the Earth. - **Magma** and **lava** are both molten rocks. However, they differ in location. - **Magma** is found in the magma chamber of the volcano while **lava** is found on the surface of earth once the volcano erupts. - **Magmatism** is a process under the earth's crust where formation and movement of magma occur. - These happen in the lower part of the Earth's crust and in the upper portion of the mantle, known as **asthenosphere.** - **Heat, water and pressure** influence the formation of magma Composition of magma **The magma present in the lower crust and upper mantle of the Earth is formed or generated through the process of partial melting.** **Partial melting- a process where different minerals in rock melt at different temperature and pressure. Another factor being considered in this process is the addition of volatile materials such as water and carbon dioxide.**  **Melting in the mantle requires one of three possible events to occur:** 1. **AN INCREASE IN TEMPERATURE:** **Conduction in mantle happens when heat is transferred from hotter molten rocks to the Earth's cold crust.** **This process is known as heat transfer. As magma rises, it is often hot enough to melt the rock it touches. It happens at convergent boundaries, where tectonic plates are crashing together.** ***Rocks are composed of minerals. These rocks start to melt once the temperature in the lower crust and upper mantle increases or exceeds the melting point of minerals. The temperature of mantle is around 1200 degrees Celsius. Rock minerals such as quartz and feldspar begin to partially melt at around 650-850 degrees Celsius.*** **2. A DECREASE OF PRESSURE:** **Mantle rocks remain solid when exposed to high pressure. However, during convection, these rocks tend to go upward (shallower level) and the pressure is reduced. This triggers the melting of magma. This is known as *decompression melting*. This process occurs at the Mid-Ocean Ridge, an underwater mountain system.** **3. ADDITION OF VOLATILES:** **When water or carbon dioxide is added to hot rocks, *flux melting* occurs. The melting points of minerals within the rocks decrease. If a rock is already close to its melting point, the effect of adding these volatiles can be enough to trigger partial melting. It occurs around subduction zones.** **3 Types of magma:** 1\. [Basaltic](https://www.britannica.com/science/basalt) (or mafic) magma predominates in nonexplosive volcanic eruptions. It is a high-temperature magma (1,200 °C \[about 2,200 °F\]) characterized by flowing lava, and it is made up of about 45--55 percent [silica](https://www.britannica.com/science/silica) (SiO~2~) by weight. 2\. [Rhyolitic](https://www.britannica.com/science/rhyolite-rock) magmas are characteristic of the most explosive eruptions, which also produce ash falls and pyroclastic flows. The temperature of rhyolitic (or felsic) magma is much lower (750--850 °C \[about 1,400--1,560 °F\]), but its silica content is higher, ranging from about 65 to 75 percent by weight.  3\.. [Andesitic](https://www.britannica.com/science/andesite) magma is intermediate in temperature (800--1,000 °C \[about 1,470--1,830 °F\]) and silica content. **LESSON 3: Changes in Mineral Components and Texture of Rocks (Metamorphism)** ***[Metamorphism]*** is the change that takes place within a body of rock as a result of it being subjected to conditions that are different from those in which it is formed. It is from the Greek word **["meta" means change and "morphe" means form.]** **METAMORPHIC ROCK** is formed at the surface of the Earth through the process of metamorphism with recrystallization of minerals in rocks due to changes in pressure and temperature conditions. The three main factors/agents of metamorphism include heat, pressure and chemically active fluids. - The heat perhaps is the most important factors because it provides the energy to drive the chemical changes which results in the recrystallization of minerals. The heat increases as the depth increases. - Pressure just like heat, also increases with depth, and the buried rocks are subjected to the force or stress. Heat and pressure cause physical changes to buried rocks. - Chemically active fluids enhanced the metamorphic process. Usually, the common fluid which helps the chemical activity is water containing ions in solution. As the rocks buried deeply, the water is forced out of the rock and becomes available to aid in chemical reactions. **\ Sea Floor Spreading\ \ **According to this theory, hot, less dense material from below the earth's crust rises towards the surface at the mid-ocean ridge. This material flows sideways carrying the seafloor away from the ridge, and creates a crack in the crust. The magma flows out of the crack, cools down and becomes the new seafloor.  Overtime, the new oceanic crust pushed the old oceanic crust far from the ridge. It allows the creation of new bodies of water. When an oceanic plate and a continental plate collide, a subduction zone occurs.\ **[Subduction]** -- Process by which the ocean floor sinks beneath a deep-ocean trench and back into the mantle **Findings that Support the Sea floor Spreading Theory\ 1.** Rocks are younger at the mid-ocean ridge.\ 2. Rocks far from the mid-ocean ridge are older.\ 3. Sediments are thinner at the ridge.\ 4. Rocks at the ocean floor are younger than those at the continents.\ 5. Magnetic reversal **Magnetic reversal** is also called as "flip" of the earth. This is due to the change in the direction of flow in the outer core.\ So when magnetic reversal occurs, there is also a change in the polarity of rocks. This is why there is magnetic stripes in the ocean floor. The stripes on both sides are of equal size and polarity which seemed to be mirror images across the ocean ridge which indicates that the seafloor is spreading. **Structure and evolution of the ocean basin** **Continental shelf** The continental shelf is part of the continental crust. It is the part of a continent that is underwater. The continental shelf is located in shallow water. The continental shelf extends roughly 330 to 600 feet from land and gradually slopes out to sea. If you have stepped off the sand on a beach and into ocean water, you have walked on the continental shelf. **Continental slope** The continental slope borders the continental shelf. Like the continental shelf, the continental slope gradually slopes out to sea, causing the water to get deeper. The continental slope\'s decline is much steeper than the continental shelf, and can even appear to drop off completely in some places. The continental slope is about 200,000 miles long and ranges from 330 to 10,500 feet deep. **Continental rise** Following the continental slope is the continental rise. In these places, ocean and continental sediments build up to form large gently-sloping masses that rise up in some places. **Mid-ocean ridge** Mid-ocean ridges, also called *oceanic ridges*, are chains of mountains on the ocean floor. Often these mountains are volcanic. About 50,000 miles of oceanic ridges make up the ocean floor. **Trench** Oceanic trenches are formed by moving plates that are a part of the Earth\'s crust. These moving plates are called* tectonic plates*. As these plates move, deep valleys can form underwater. These underwater valleys are called *trenches* and range in depth from 24,000 to 36,000 feet. Trenches are mostly unexplored territory because their depth prevents scientists from visiting them. **Seamount** Seamounts are ocean volcanos. **Guyot** Guyots are flattop ocean volcanos. **Stages of Ocean Basin Evolution** ----------------------------------- ***[The Wilson Cycle]*** explains the process of the opening (beginning) and the closing (end) of an ocean. 1^st^: **Embryonic** -------------------- ** example:  Great Rift Valley, Eastern Africa** 2^nd^: **Juvenile** ------------------- ** example:   Red Sea** 3^rd^: **Mature** ----------------- -broad ocean basin widens, trenches develop and subduction begins -ocean basin with continental margins **example:  Atlantic ocean** 4^th^: **Declining** -------------------- -subduction eliminates much of sea floor and oceanic ridge -island arcs and trenches around basin edges **example:    Pacific Ocean** 5^th^: **Terminal** -------------------             -narrow ocean basin, possibly shallowing because of sediment input young mountain ranges along flanks - Narrow irregular seas with young mountains **          example:    Mediterranean Sea, Persian Gulf** 6^th^: **Suturing** ------------------- ** example:   Himalayas and Tibetan Plateau** **LESSON 4: MOVEMENT OF PLATES AND FORMATION OF FOLDS AND FAULTS**  **Transform Plate Boundary** -It is also called as strike slip fault boundary, the plates slide past each other horizontally. This is a type of boundary that cuts through California, the well-known San Andreas Fault. The San Andreas fault zone, which is about 1300 km long and is tens of kilometer wide, slice through two thirds of the length of California. Along with it, the Pacific Plate has been for 10 million years, at an average rate of about 5cm/yr (Pavico and Faraon, 2007, 193). **Convergent Plate Boundary** -The heavier oceanic crust sinks below the lighter continental crust. It happens along convergent boundaries where plates are moving toward each other and sometimes one plate sink under another (subduction). Marianas Trench marks where the fast-moving Pacific Plate converges against the slower moving Philippine Plate. This boundary is often sits of major volcanoes such as Mount Fuji in Japan. In a collision of two pieces of oceanic crust, the result is a chain of volcanic islands, of which Indonesia is a prime example. Where oceanic crust collides with a plate carrying continent, the result is a chain of volcanoes on the continent such as the Cascade of volcanic chain in Pacific Northwest of the US and the Andes Mountains of South America. When two continental crusts collide, the result is a range of mountains such as Himalayan Mountain yr (Pavico and Faraon, 2007, 193-194). **Divergent Plate Boundary** -Divergent Plate Boundaries are boundaries where the earth's tectonic plates are moving apart. For most part, these boundaries are located on the ocean floors, where they form a continuous chain of volcanic mountains and rift called mid-ocean ridges that extend throughout the earth's oceans. MidAtlantic Ridge is good example which runs down the middle of the Atlantic Ocean. As the plates move apart, magma wells up to fill the space between them, and this is why divergent plate boundaries are the sites of volcanic activity. It is also a set where the earth's crust is growing (Pavico and Faraon, 2007, 194). Plates move relative to each other and to fixed location in the mantle of the Earth. The absolute motion of the plates can lead to the formation of strings of volcanoes. On the other hand, their relative motion can lead to the different types of plate boundaries. If three plates meet in one place, they form a triple junction (Kasten 2012, 241) Currently, the size of oceans and shape of continents are changed due to the movement of plates. Because of the movement of plates in North and South America, Pacific Ocean is becoming smaller. However, the Atlantic Ocean is becoming larger as North and South America move away from Europe and Africa. The Himalayas Mountains are becoming taller. The plate that includes Australia is now beginning to collide with the plate that includes Southeast Asia. India's plate is also colliding with Asia while Australia is moving farther away from Antarctica (Kasten 2012, 241). **THE FOLDING AND FAULTING OF ROCKS** **FOLDING** - The horizontal movement of the earth's crust results in folding **FAULTING** - The vertical movement of the earth's crust involves uplift or subsidence of crust along the lines of weakness. - The rapid movement causes the ground to shake and vibrate, resulting in earthquake. **3 TYPES OF STRESS** There are 3 types of stress that can affect rocks, resulting in 3 different types of fault. 1\. **TENSION**- also called EXTENSION -rocks are being pulled apart (stretches) and creates valley 2\. **COMPRESSION**- rocks are being pulled together and creates mountains 3\. **SHEARING**- rocks slide past each other resulting in strike-slip fault causing the rocks to break resulting in earthquake **TYPES OF FAULTS** **1. Normal fault** - **Tension in Earth's crust pulls rock apart, causing normal faults.** - **In a normal fault, the fault is at an angle, so one block of rock lies above the fault while the other block lies below the fault.** - **The block of rock that sits over the fault is called the hanging wall.** - **The rock that lies under the fault is called the footwall.** - **When movement occurs along a normal fault, the hanging wall slips downward.** - **Normal faults occur where plates diverge, or pull apart.** **2. Reverse faults** - **Compression in Earth's crust pushes rock together, causing reverse faults.** - **A reverse fault has the same structure as a normal fault, but the blocks move in the opposite direction.** - **The rock forming the hanging wall of a reverse fault slides up and over the footwall.** **3. Strike-slip fault** - **In places where plates move past each other, shearing creates strike-slip faults.** - **In a strike-slip fault, the rocks on either side of the fault slip past each other sideways, with little up or down motion.** **LESSON 10: ROCK LAYERS** The idea behind the concept that the Earth is billions of years old originated in the work of James Hutton. Hutton concluded that there are forces that changes the landscape of the Earth in the past. This conclusion is based on his observation in the geological processes that were taking place in his farm. His Principle of Uniformitarianism states that the current geologic processes, such as volcanism, erosion, and weathering are the same processes that were at work in the past. This idea was refined by other geologists that although the process of the past and the present are the same, the rates of this process may vary over time. The Earth's history was studied using the different records of past events preserved in rocks. The layers of rocks are like the pages in our history book How are rock layers formed? Stratified rocks, also known as derivatives rock, maybe fragmental or crystalline. These rocks are products of sedimentary processes. These are made of visible layers of sediments. The formation on rock layers depend on its stratigraphy and stratification.  Stratigraphic Laws Stratigraphic laws are basic principles that all geologists use in decoding or deciphering the spatial and temporal relationships of rock layers. These includes the following: ***Original Horizontality, Lateral Continuity, Superposition, Cross Cutting, Law of Inclusions and the Law of Faunal Succession.***  **LESSON 11: CORRELATION OF ROCK LAYERS** One of the evidences used by geologist in tracing the history of the Earth was with the identifications and the correlations of rock layers. Rock layers were subjected to alteration due to different geologic processes that act or apply on it. Such forces could result to tilting, uplifting, compression, and subductions of rock layers. These rock layers have the tendency to be separated from each other. One way of how these rock layers are identified is with the utilization of correlation. Why do geologists need to correlate rock layers? The history of earth is preserved in its rock layers. Unfortunately, no single location on earth has a continuous set of layers due to erosion or ceased deposition. Instead, geologists study rock sequences at many different places around the world, measure the depth of the layers, record what kind of rock is in each layer, and see if there are any fossils present. Geologists represent the layers of rock by drawing a picture of the sequence -- this is called a **stratigraphic column.** Geologists need to correlate rocks from one place to another to get more complete record of Earth's history over time. They try to determine the relative age of widely separated strata or rock layers. They used correlation trying to fit together sedimentary strata in different places just like a cut-out puzzle. How do geologists correlate rock layers? The process of showing that rocks or geologic events occurring at different locations are of the same age is called **correlation**. Geologists have developed a system for correlating rocks by looking for similarities in composition and rock layer sequences at different locations The geological technique of correlation provides information that have taken in Earth's history at various time that occurred. There are different methods in correlating rock layers, these includes: 1\. Rock types and its characteristics color, texture, hardness, composition or its mineral content the harder and more densely packed the particles are, the older the rock and the deeper the layer it came from. 2\. Index fossil also known as guide fossils or indicator fossils, are fossils used to define and identify geologic periods (or faunal stages) 3\. Bed rock a deposit of solid rock that is typically buried beneath soil and other broken or unconsolidated material (regolith). made up of igneous, sedimentary, or metamorphic rock, and it often serves as the parent material for regolith and soil. How to match correlated rock layers? Matching of rock layers may be determined by merely looking at its features. Look at the three columns of rock layers below. Let us determine how they are correlated.  After matching correlated rock layers, we can determine the relative age of each layer according to the law of superposition. Limestone in location A is the oldest and limestone in location C is the youngest rock layer. While those rock layers having the same composition, textures, and fossil content were considered as rock layers with the same age. In matching up rock layers, superposition and cross-cutting are helpful. When rocks are touching one another, the lateral continuity rock layers aid to match up with the layers that are nearby. Geologists then match, or correlate, the different shorter sequences to create a geological column that spans further back into earth's past. Correlations involve matching a particular rock unit in one exposure with its counterpart at a different locality. By correlating various rock vulnerability separated by great distances, geologic maps can be constructed and the original geographical extent of the rocks can be estimated. Types of Correlation A\) **Physical Correlation** is accomplished by using number of criteria such as color, texture, and types of minerals contained within a stratum which make it possible for geologists to classify a particular stratum specifically. B\) **Fossil Correlation** is a principle that geologists use to determine the age of rock. It uses fossil with unique characteristics, such as geologically short lifespan and easily identifiable features and use this information to estimate the age of a rock layer in other areas that contain the same type of fossil or group of fossils There are fossils which are used to date the layers of rock that they are found in. Fossils that can be used in this way are called **index fossils**, and rock layers with the same index fossils in them can be correlated. Criteria to be considered in identifying index fossils includes: 1\. The fossilized organism must be easily recognizable and it must be easy to identify because of its uniqueness. 2\. Fossils must be geographically widespread, or found over large areas so that it can be used to match rock layers separated by huge distances. 3\. Fossils must have lived for only a short time, so that it appears in only horizontal layer of sedimentary rocks. **LESSON 12: RELATIVE AND ABSOLUTE DATING** **Relative Age** Prior to absolute age measurements, geologist used field observations to determine the relative ages. They used simple principle in order to get the relative ages. The following are the principles used by the geologists: The **principle of original horizontality** is based on the observation that sediment usually accumulates in horizontal layers. Tectonic forces tilted or folded rocks into an angle after it was formed. The **principle of superposition** states that sedimentary rocks become younger from bottom to top. This is because younger layers of the sedimentary always accumulates at the top of the layers. In figure 4, rocks number 5 are oldest and rocks in 1 are the youngest. The **principle of crosscutting** relationships is based on the fact that rocks must exist before anything else happened like intrusions or dike cutting across rocks. In figure 5, the cut rock layers are older than the rock that cuts across them. The **principle of faunal succession** states that species succeeded one another through time in a definite and recognizable order and that the relative ages of sedimentary rocks can be therefore recognized from their fossils. The absence or the presence may be used to give a relative age of the sedimentary where they are found. The **principle of lateral continuity** explained that layers of sediment are continuous. Layers with same rocks but separated by a valley or erosion are initially continuous. **Absolute Age** Since change is the only thing that is permanent, the measurement of absolute age or exact date became a challenging task to the scientists. But they found a natural process that occurs at constant rate and accumulates its record of the radioactive decay of elements in rocks. Radioactive elements decay because they are composed of unstable isotopes that decompose spontaneously. Each atom has a certain probability of decaying at any time. It has half-life or time for it to decompose into half. Radioactivity is not affected by geologic process and easily measured in the laboratory. Aside from those, daughter isotopes accumulate in rocks. The longer the rock exists, the more daughter isotopes accumulate. The process of determining the absolute ages of rocks and minerals by measuring the relative amounts of parent and daughter isotopes is called radioactive dating. e.g. a form of uranium changes (decays) to lead In the above example, the parent element is uranium (U) and the daughter element is lead (Pb). Again, the process of radioactive decay can be used for dating rocks because: ***Radioactive decay proceeds at a constant, regardless of changes in conditions such as temperature, pressure, or the chemical environment.*** Here are the commonly used radioactive isotopes in radioactive dating:  Half-Life It is almost impossible to say when the last of the parent atoms will decay, but the time taken for half the atoms to decay is comparatively easy to predict. The half-life of a radioactive decay process is the time taken for half the original parent atoms to decay. The length of half-life is a unique feature of each decay process. The half-life of the uranium is 713 million years. This means that if an igneous rock contained 1000 atoms of U-235 when it solidified: After 713 million years, it would contain 500 atoms of U-235 and 500 atoms of the daughter element for the decay process, Pb-207. The proportion of parent atoms/daughter atoms present in an igneous rock gives the age of the rock --- or the number of million years since the rock solidified. **LESSON 13: GEOLOGIC TIME SCALE** Deposition of sediments contribute to reshaping the surface of the Earth. Deposits are laid down by different environmental factors such as volcanic eruption, erosion, weathering debris of rocks (clay and silts) and even all its fossil content and historical information. Earth history including its rock strata, the rock study, and discovery, as well as the fossils, are engraved in one of the most important materials known as geologic record. The geologic time scale is the "calendar" for events in Earth's history. The importance of geologic time scale is, it serves as a standard timeline used to describe the age of rocks, fossils, and the events that formed them. It is a device which is of great help to the science of geology and it is owed to the explorations and studies recorded by geologists. Knowing about how life began in the past, the events, and principles behind the Earth's history enables us to conform with the alterations or consequences that we might encounter or experience in the near future. As a part of the new generation, we should be appreciative and accept that all things that are present in our time were the outcomes of the Earth's history. Since the beginning, geologists have been studying the Earth to unwrap the secrets of the past. They have been analyzing rock samples gathered from different continents in the world including its layers and its correlation with the fossils. This helps in relating the sequence of events in the Earth's history which is clearly presented in the geologic time scale. The geologic time scale is divided into a series of time intervals which are equal in length. These time intervals are different from that of a clock. They are divided according to the significant events in the history of Earth such as the mass extinction of a large population of fauna and flora.  **Relative and Absolute Dating** Scientists first developed the geologic time scale by studying rock layers and index fossils. The information gathered by the scientists placed the Earth rock strata in order by relative age. Geologic time is often discussed in two forms: relative time and the absolute time. Relative time is a subdivision of the Earth's geology in a specific order based upon the relative age relationships (commonly, vertical or stratigraphic position). Relative time can be established usually on the basis of fossils. On the other hand, absolute time refers to the numerical ages in millions of years or some other measurement. These are obtained by radioactive dating methods performed on appropriate rocks. Relative time can be referred to as the physical aspects found in rocks while the absolute time refers to the measurements taken upon those to determine the actual time it expired. The time scale is depicted in its traditional form with the oldest at the bottom and the youngest at the top. **Things to Ponder:** Geologic time scale is a timeline that illustrates Earth's past. Geologic time scale describes the order of duration of major events on Earth for the last 4.6 billion years. Geologic time scale was developed after the scientist observed changes in the fossils and rocks going from oldest to youngest sedimentary rocks. Geologic time scale was divided into four divisions which include the Eons, Era, Period, and Epoch. Eons is the largest division in the geologic time scale. Relative dating or age is the order of the rocks from oldest to youngest. Relative dating does not determine the exact age of rock or fossils but does learn which one is older or younger than the other. Relative age of rocks based on the order gives its physical division in the geologic time scale. Absolute dating or age measures the amount of radioactive elements in rocks to give the ages to each division of time in the geologic time scale. Absolute time refers to the numerical ages in millions of years or some other measurement. **LESSON 14: GEOLOGICAL PROCESSES** How do geological processes occur? Geological processes are naturally occurring events that directly or indirectly impact the geology of the Earth. Examples of geological processes include events such as plate tectonics, weathering, earthquakes, volcanic eruptions, mountain formation, deposition, erosion, droughts, flooding, and landslides. Geological processes affect every human on the Earth all of the time, but are most noticeable when they cause loss of life or property. These threatening processes are called natural disasters. How about Geologic Hazards? A geologic hazard is an extreme natural event in the crust of the earth that poses a threat to life and property, for example, earthquakes, volcanic eruptions, tsunamis (tidal waves) and landslides. It is a large-scale, complex natural events that happen on land. These hazards can cause immense damage, loss of property, and sometimes life. Geologic hazards can play a significant role when infrastructure is constructed in their presence. The unpredictable nature of natural geologic hazards makes identifying, evaluating, and mitigating against them a unique challenge. Geologic processes and hazards are events which occur irregularly in time and space and cause negative impact on man and the environment. Earthquakes, volcanic eruptions, tsunamis (tidal waves), and landslides are the geologic hazards.  Earthquake is one of the most violent natural phenomena. According to the number of victims and destructive force, it exceeds all other natural disasters. Earthquakes also happen under the ocean and can cause tsunamis. Earthquakes and volcanic eruption can trigger landslides, especially in areas with water saturated soils, a common characteristic of Cascadia. Landslides may result in falling rocks and debris that collide with people, buildings, and vehicles. There were earthquakes that happened in the Philippines which were noticeably strong such as magnitude 6.9 in October 2019 which hit southern Philippines. Another one was 6.1 magnitude that struck the Island of Luzon in April of 2019. Recently, multiple earthquakes were felt when Taal Volcano erupted early in 2020. Listed below are the hazards caused by an earthquake: **A. Ground shaking is one of the hazards resulting from earthquake, volcanic eruption, and landslides. Ground shaking is both a hazard created by earthquakes and the trigger for other hazards such as liquefaction and landslides. Ground shaking describes the vibration of the ground during an earthquake.** **B. Surface faulting is displacement that reaches the earth\'s surface during slip along a fault. It commonly occurs with shallow earthquakes; those with an epicenter less than 20 km. Surface faulting also may accompany aseismic creep or natural or man-induced subsidence.** **C. A landslide is defined as the movement of a mass of rock, debris, or earth down a slope. Landslides are a type of \"mass wasting,\" which denotes any down-slope movement of soil and rock under the direct influence of gravity. The term \"landslide\" encompasses five modes of slope movement: falls, topples, slides, spreads, and flows.** **D. Liquefaction describes the way in which soil liquefies during ground shaking. Liquefaction can undermine the foundations and supports of buildings, bridges, pipelines, and roads, causing them to sink into the ground, collapse, or dissolve.** **E. Tsunamis are giant waves caused by earthquakes or volcanic eruptions under the sea. It can injure or kill many people and cause significant damage to buildings and other structures. The speed of tsunami waves depends on ocean depth rather than the distance from the source of the wave. Tsunami waves may travel as fast as jet planes over deep waters, only slowing down when reaching shallow waters.** What are volcanoes? Volcanoes can be exciting and fascinating, but are also very dangerous. Any kind of volcano can create harmful or deadly phenomena, whether during an eruption or a period of dormancy. Volcanoes are natural systems and always have some element of unpredictability. What about volcanic eruption? A volcanic eruption occurs when magma is released from a volcano. Volcanic eruptions are major natural hazards on Earth. Volcanic eruptions can have a devastating effect on people and the environment. These are the hazards caused by volcanic eruption: **A. Tephra consists of pyroclastic fragments of any size and origin. It is a synonym for \"pyroclastic material.\" Tephra ranges in size from ash (64 mm).** **B. A pyroclastic flow is a dense, fast-moving flow of solidified lava pieces, volcanic ash, and hot gases. Pyroclastic flows form in various ways. A common cause is when the column of lava, ash, and gases expelled from a volcano during an eruption loses its upward momentum and falls back to the ground. Another cause is when volcanic material expelled during an eruption immediately begins moving down the sides of the volcano. Pyroclastic flows can also form when a lava dome or lava flow becomes too steep and collapses.** **C. Lahar is an Indonesian term that describes a hot or cold mixture of water and rock fragments that flows down the slopes of a volcano and typically enters a river valley. Lahars are extremely dangerous especially to those living in valley areas near a volcano. Lahars can bury and destroy manmade structures including roads and bridges.** **D. A flood is an overflow of water that submerges land that is usually dry. Floods can look very different because flooding covers anything from a few inches of water to several feet.** **E. Lava domes are formed by viscous magma being erupted effusively onto the surface and then piling up around the vent. Like lava flows, they typically do not have enough gas or pressure to erupt explosively, although they may sometimes be preceded or followed by explosive activity. The shape and size of lava domes varies greatly, but they are typically steep-sided and thick.** **F. Poisonous gases, the gases that are released during a volcanic eruption, come from deep within the Earth. The largest portion of gases released into the atmosphere is water vapor.** The Philippines has suffered from an inexhaustible number of deadly typhoons, earthquakes, volcanic eruptions and other natural disasters. This is due to its location along the Ring of Fire, or typhoon belt -- a large Pacific Ocean region where many of Earth's volcanic eruptions and earthquakes occur. Taal Volcano, on the island of Luzon in the Philippines, is the country\'s second most active volcano. It boomed to life on January 12,2020, Sunday afternoon, spilling volcanic ash. Taal Volcano sent a massive plume of ash and steam spewing miles into the sky and pushed red-hot lava out of its crater, prompting the evacuation of thousands of people and the closure of Manila\'s airport. Hundreds of earthquakes were noted while the volcano was erupting. Flashes of lightning lit up the plume, lending the scene an otherworldly appearance. **LESSON 15: GEOLOGICAL HAZARDS** The Philippines is an archipelago that is made up of 7641 islands and home to world-renown natural wonders and pristine water bodies. The country is in a unique location because it rests in the Pacific Typhoon Belt and Pacific's earthquake and volcano Ring of Fire. The Ring of Fire is a home to over 75% of the world's active and dormant volcanoes. Because of its geographic location, the Philippines is among the greatest hazard and disaster-prone countries in the world. The Philippines is no stranger to natural hazards. Every year, thousands to millions of Filipinos are extremely affected by all forms of hazards such as earthquakes, typhoons, and volcanic eruptions. These natural hazards may result in multiple disasters. **Geologic Process** Geological processes can be described as natural forces that shape the physical makeup of a planet. These forces cause movements of plates in the Earth's crust, the area where humankind lives. As these processes occur from time to time, it poses continuous source of hazards to people, community and society. **Hazards** A hazard is a phenomenon caused by natural or human forces which poses threat to humans, animals, properties and environment. For instance, since the Philippines is located within the Ring of Fire, the country experiences many earthquakes and volcanic eruptions compared to other countries. Making the country one of the most hazard-prone countries in the world. Hazards can be classified as to natural and anthropogenic. Natural: Earthquakes, volcanic eruptions, landslides and tsunamis (climate and weather related hazards) Anthropogenic: Deforestation, mining and climate change (man-made) **Hazard Map** It is a map that illustrates the areas that are exposed or prone to a particular hazard. They are used for natural hazards such as landslides, flooding, volcanic eruption and tsunami. It is also used to mitigate the potential negative effects of these hazards. Now, you have learned that geologic location is the major reason why the Philippines is a hazard-prone country. The Philippine government partnered other private institutions to reduce the risk of hazards through producing hazard maps that are publicly available. For example, the partnership of news networks with the Philippine Institute of Volcanology and Seismology (PHIVOLCS). This partnership shares valuable and scientific information which increases the public's understanding on geologic hazards and risks associated with it. Another is Manila Observatory, a private non-stock and non-profit research institution with the help of the Department of Environment and Natural Resources (DENR. This partnership produced hazard maps that show vulnerability of the country to environmental disasters.  **Landslide** is the movement of rock down a slope where human activities play an important role in speeding up or triggering its occurrences. Landslide is an occurrence in which soil, rocks and vegetal debris are transported suddenly or slowly down a slope due to insufficient stability. It may happen when there is continuous rainfall, earthquakes and/or volcanic eruption accompanied by a very loud noise. Landslide can be resulted from the failure of the materials to make up the hill slope, and get driven by the force of gravity. Landslide is also known as landslips, slumps or slope failure. Listed below are some of the human activities that speed up or trigger landslide: **a. Overloading slopes** **b. Mining which uses explosives underground** **c. Excavation or displacement of rocks.** **d. Land use such as modification of slopes by construction of roads, railways, buildings, houses, etc.** **e. Quarrying which includes excavation or pit, open to the air, from which building stone, slate, or the like is obtained by cutting, blasting, etc.** **f. Land pollution which is the degradation of earth's land surface, exploitation of minerals and improper use of soil by inadequate agricultural practices.** **g. Excavation which pertains to exposure, processing, and recording of archaeological remains** **h. Cutting Trees that can lead to deforestation and may encourage landslide** Due to these human activities, several effects of landslides were noted. These cause property damage, injury and death and adversely affect a variety of resources. For example, water supplies, fisheries, sewage disposal systems, forests, dams and roadways can be affected for years after a slide event. The negative economic effects of landslides include the cost to repair structures, loss of property value, disruption of transportation routes, medical costs in the event of injury, and indirect costs such as lost timber and lost fish stocks. Water availability, quantity and quality can be affected by landslides. Geotechnical studies and engineering projects to assess and stabilize potentially dangerous sites can be costly. Are we prepared in case of landslides? These are some precautionary measures to observe and follow in preparing for landslides: **a. Stay alert and awake. Many debris-flow fatalities occur when people are sleeping.** **b. If you are in areas susceptible to landslides and debris flows, consider leaving if it is safe to do so.** **c. Listen for any unusual sounds that might indicate moving debris, such as trees cracking or boulders knocking together.** **d. If you are near a stream or channel, be alert for any sudden increase or decrease in water flow and for a change from clear to muddy water.** **e. Be especially alert when driving. Bridges may be washed out, and culverts overtop.** **f. Be aware that strong shaking from earthquakes can induce or intensify the effects of landslides**. **LESSON 16: HYDROMETEOROLOGICAL HAZARDS** The Philippines has a tropical and maritime climate. Annually, the country is visited by an average of 20 typhoons, five to nine of which are highly destructive. The Philippines is situated in the Pacific typhoon belt thus, the country is highly prone to hydrometeorological hazards. Oftentimes, multiple hazards occur simultaneously. **Hydrometeorological hazards** - They are brought by extreme meteorological and climate phenomena that includes tropical cyclones, thunderstorms, tornado (ipo-ipo) drought, and floods. 1\. Tropical cyclones Tropical cyclones are known in various names depending on the country where you live. In the Western North Pacific around the Philippines, Japan, and China the storms are known as typhoons, while in the North Atlantic Ocean and the Eastern North Pacific they are referred to as hurricane. Here are the top five destructive typhoons to ever hit the country: Typhoon Haiphong (1881), Typhoon Haiyan (Yolanda) (2013), Tropical storm Thelma (Uring) (1991), Typhoon Bopha (Pablo) (2012), and Typhoon Angela (1867). 2\. Monsoons A monsoon is a seasonal wind and rains pattern, and the word "monsoon" believed to be originated from the Arabic word mawsim (season), via Portuguese and the Dutch monsun. There are two known monsoons in the Philippines that occur every year: Summer Southwest (Habagat) and Winter Northeast Monsoon (Amihan). 1\. Amihan: brings cloudless skies and nippy mornings during the dry season (October to late March) 2\. Habagat: brings heavy rains and some deadly typhoons (June to September) 3\. Floods Flood is as an abnormal progressive rise in the water level of a stream that may result in the over-flowing by the water of the normal confines of the stream. A flood can vary in size, speed of water, and duration. 4\. Tornado (Ipo-ipo) A tornado is a narrow, violently rotating column of air that extends from a thunderstorm to the ground. The main cause of tornadoes are thunderstorms though tornadoes are not common in the Philippines, still it can occur at any time of the year. **LESSON 16: COASTAL PROCESSES AND HAZARDS** **Coastal processes** are unavoidable occurrences driven by nature and amplified by human action. They cause damage to the shorelines through coastal erosion, submersion, and saltwater intrusion. **What is coastal erosion?** Erosion is the wearing away of the land by the sea. This often involves [[destructive waves]](http://www.geography.learnontheinternet.co.uk/topics/waves.html#destructive) wearing away the coast.\ There are five main processes which cause coastal erosion. These are corrasion, abrasion, hydraulic action, attrition and corrosion/solution. **1. Corrasion **is when waves pick up beach material (e.g. pebbles) and hurl them at the base of a cliff. **2. Abrasion **occurs as breaking waves which contain sand and larger fragments erode the shoreline or headland**. **It is commonly known as the sand paper effect. 3\. When waves hit the base of a cliff air is compressed into cracks. When the wave retreats the air rushes out of the gap. Often this causes cliff material to break away. This process is known as **hydraulic action**. **4. Attrition** is when waves cause rocks and pebbles to bump into each other and break up. **5. Corrosion/solution** is when certain types of cliff erode as a result of weak acids in the sea. **Coastal Protection** - **Coastal protection** involves methods and structures that prevent coastal erosion and submersion. Examples of these structures are **seawalls**, **gyrones**, and **breakwaters**. - **Beach nourishment** and installation of small walls made of **sandbags** are other methods of coastal protection. - Reducing coastal erosion involves methods that minimize the erosion already occurring on the coasts. - **Beach dewatering**, **construction of buildings in a safe distance** from the water, **ban of mining activities**, and **maintaining plant cover** are some examples of ways to reduce coastal erosion. - Coping with saltwater intrusion involves three major steps: **monitoring and assessment**, **regulation**, and **engineering structures**.