DRRR-Unit-6-Other-Related-Geological-Hazards PDF

Unit 6 Other Related Geological Hazards Table of Contents Introduction 3 Essential Questions 4 Lesson 1: Ground Subsidence 5 Starting Out...

Unit 6 Other Related Geological Hazards Table of Contents Introduction 3 Essential Questions 4 Lesson 1: Ground Subsidence 5 Starting Out 5 Learn about It 5 Check Your Understanding 11 Explore Your World 12 Case Study 13 Lesson 2: Rainfall-Induced Landslide 14 Starting Out 14 Learn about It 14 Check Your Understanding 20 Explore Your World 20 Case Study 22 Lesson 3: Coastal Erosion 23 Starting Out 23 Learn about It 23 Check Your Understanding 28 Explore Your World 29 Case Study 30 Lesson 4: Bolide Impact 31 Starting Out 31 Learn about It 31 1  Check Your Understanding 35 Explore Your World 36 Case Study 37 Real World Challenge 38 Check and Reflect 40 Wrap Up 40 Bibliography 42 Glossary 43 Answers to Check Your Understanding 44 2 GRADE 11/12 |Disaster Readiness and Risk Reduction UNIT 6 Other Related Geological Hazards As an archipelagic country, the Philippines is blessed with vast coastlines or shorelines and diverse types of islands in varied sizes. These islands are made of different topographical and geophysical components. Coastlines of the country are varied, there are cliff shorelines in the northernmost and easternmost islands, beach barriers in different colors of sand are common sceneries in many places; and there are salt marshes in other parts. These coastlines are exposed to a certain type of hazard called coastal erosion. Wave height and the climatic conditions of the place could cause coastal erosion. Mountainous sides of the country bring rich biodiversity but pose the risk of natural or anthropogenic landslide. Another hazard that poses threats to human lives and properties is ground subsidence, since there are places in the country where limestone and clay are the dominant components of the bedrock. Awareness plays an important role in readiness. Valid and data-driven information should be disseminated for the preparedness of Filipinos in the context of hazards. Fig. 1. One of the numerous beaches in the Philippines. 3  Essential Questions What are the possible causes of geological hazards? How do different geological hazards affect human lives? What are the signs of impending geological hazards? How are geological maps interpreted? How do mitigation strategies aid in the prevention of loss of lives and properties? In this unit, you should be able to: discuss different geological hazards; analyze the causes of geological hazards; recognize signs of impending geological hazards; interpret geological maps; and apply mitigation strategies to prevent loss of lives and properties. Geological processes are natural processes that change the earth’s landscape. Weathering, erosion, deposition and sedimentation are examples of geological processes that can change the earth’s surface over long periods of time. Earthquake, volcanic eruption, and landslide are examples of geological processes that can change the surface abruptly. The plates that make up the earth’s crust are in constant motion. Soil is a product of weathering of rocks of different composition. 4 Certain types of areas can collapse without warning and form what is known as sinkholes. How do sinkholes develop? Think–Pair–Share: Each learner will find a pair. SCENARIO: Your community including your house is located on top of limestone. This type of rock is easily carved by underground water especially during rainy season. What do you think would be the effect of the underground current to your community, which is found on the surface of the limestone? On February 23, 2007, a massive and deep circular hole with vertical walls abruptly appeared in a street junction in one of the settlement areas in Guatemala. There were five (5) people instantly killed during the incident. Scientists called the phenomenon, a sinkhole. A sinkhole can be described as the downward movement of earth’s crust towards its gravity. It is the sinking of the ground surface above an underground void or depression. Sinkholes could be due to the collapse of an old mine or cave, and deterioration or compaction of soils and construction materials used for filling (Pittsburgh Geological Society). In the case of the 2007 Guatemala sinkhole, there was no natural reason why it happened. It occured because of the unstructured city sewerage system that eroded the uncemented volcanic ash, limestone, and other pyroclastic deposits underneath. Weeks before the appearance of the sinkhole, residents were hearing rumbling sounds underground and reported it to proper authorities. The Guatemalan government was about to conduct a geological study on the area, when the sinkhole already appeared. 5 Ground Subsidence Ground subsidence usually occurs in urban cities and many scientists consider it as anthropogenic in nature. A lot of ground subsidence, particularly sinkholes, are the result of too much groundwater extraction in urban settlements. The overexploitation of aquifers in urban settlements and adjacent areas is a worldwide concern. Big cities with millions of people inhabiting these areas need water for daily use— for drinking, bathing, cooking, laundry, and other related activities that need water. The United States Geological Survey (USGS) defined ground subsidence as the loss of surface elevation due to the removal of subsurface support. There are diverse forms of ground failure or subsidence, many are small and local in nature, while others are broad and can affect a wider area of concern. Tomoyuki Okada (2017) from his researches in the Japanese deltas noted that the same rate or amount of decrease in groundwater level is equal to the land subsidence rate in areas affected by it. Fig. 1. Composite photo of a sinkhole that appeared in Guatemala in 2007. Eric Haddox, Guatemala city sinkhole 2007 composite view, cropped, CC BY 2.0 According to the International Hydrological Programme of United Nations Educational, Scientific, and Cultural Organization (UNESCO), land surface sinking occurs in many parts of the world, particularly in densely-populated, deltaic regions, causing extremely expensive damage. Ground subsidence has resulted from natural causes, such as tectonic motion and sea level rise. Ground subsidence can also come from man-induced causes such as the heavy withdrawal of groundwater and geothermal fluids, oil, and gas; other mining activities such as extraction of coal, sulfur, gold, and other solids; and underground construction (tunneling). 6 Also, there can be other mixed causes of subsidence such as the hydro-compaction of loosely deposited sediments; oxidation, and shrinkage of organic deposits; or the development of sinkholes in karstic terrains. Fig. 2. Illustration showing how human activities like over extraction affects ground subsidence. Sinkhole is the type of ground subsidence that occurs because the rock below the land is either limestone, carbonated rocks, or salt bed that was continuously penetrated by circulating groundwater for a long time. Due to this ong time exposure to groundwater, these types of rocks can be dissolved and eventually create spaces or caverns underground. Once these underground spaces are present, sudden collapse of the land surface is inevitable. 7 Formation of Sinkholes Sinkholes form in areas that geologists call karst terrains. Areas that are described as karst terrain have bedrocks that are typically made up of limestone, dolomite, or gypsum. Those types of rocks can be dissolved by groundwater over time. The type of bedrock in karst terrains result in features like springs, caves, and sinkholes. When acidic water (from soil and air) enters a karst terrain, it easily penetrates the area and creates horizontal and vertical cracks and crevices that lead to the development of a conduit system. A conduit or an underground river forms from the pathways created by penetrating acidic water. Because of this, underground erosion and formation of underground caves may lead to the development of sinkholes. Types of Sinkholes Type Description Dissolution Dissolution can be described as the process of dissolving of rocks, sinkholes often by water or acid. This type of sinkhole forms from dissolution of the limestone or dolomite. Dissolution happens intensively where water first comes in contact with the rock surface. It can also occur where water passes through pre-existing openings, crevices or fractures in rocks. Cover-subsidenc In areas where the covering sediments contain sand and are e sinkholes permeable, cover-subsidence sinkholes can eventually develop. In areas where the covering sediments contain more clay, cover-subsidence sinkholes may still develop but may be undetected for longer periods of time. Cover-collapse Cover-collapse sinkholes occur where the covering sediments sinkholes contain a significant amount of clay. These sinkholes may develop abruptly (over a period of hours) and cause catastrophic damages. Over time, surface drainage, erosion, and deposition of sinkhole will develop into a shallower bowl-shaped depression. Human-induced Some sinkholes are associated with human activities like sinkholes groundwater pumping, construction, and land development practices. Sinkholes can also form when water diversion systems are developed for human activities. When the land is changed due to industrial activities, the weight of new materials placed on the surface can cause the collapse of the supporting material underground, causing a sinkhole. Source: Aurelio, M.A., Dianal, J.D., and Tan, C.M., (2017). Senior High School Disaster Readiness and Risk Reduction Reader. Department of Education, Bureau of Learning Resources. Pasig City. 8 Some Causes of Ground Subsidence Ground subsidence can be a result of natural processes or as effects of human activities. Aside from dissolution and diversion of natural water drainage patterns, dewatering or overdraining of organic soil and peat can shrink the materials causing the ground to subside. Compaction of soil due to natural or man-induced processes will displace air spaces, making the soil impenetrable and more susceptible to subsidence. Subterranean mining or underground mining activities including extraction of fluid minerals displaces numerous materials under the surface. A possible effect of climate change, thawing permafrost erodes not only water but other solid materials that are part of its composition. Thawing permafrost shrinks the land and affects human and natural installations above its surface. Fig. 3. Houses built on permafrost that now has signs of subsidence. Fbaudoux.ir, Maisons sur Permafrost, CC BY-SA 3.0 9 Effects of Ground Subsidence Ground subsidence can impact agricultural lands, industrial processes, and infrastructure. Farm lands, irrigation systems, and groundwater wells can be damaged or destroyed. Infrastructures that are on subsiding ground can also be damaged or destroyed. Mining areas tunnels and surrounding areas can collapse. Moreover, sudden subsidence can cause injuries and fatalities. Some Tips to Reduce Occurrence of Ground Subsidence Human activities that can result in ground subsidence can be reduced if there is proper and planned urbanization. This means that when the government plans to build infrastructures, critical facilities, and transportation systems, risk of ground subsidence should be included as part of the major considerations. Some examples that show consideration of ground subsidence in urban planning include: finding alternative sources to groundwater; avoiding building infrastructure in certain distances near land fissures; routing drainage away from fissures; and prohibiting residential zones in or near fissure areas or types of ground that have high subsidence susceptibility. As individuals, everyone is encouraged to practice water conservation so as not to contribute to ground subsidence that may result from overdraining underground water sources. Heavy withdrawal of groundwater and geothermal fluids, oil, and gas; other mining activities such as extraction of coal, sulfur, gold, and other solids; and underground construction can result in ground subsidence. 10 A. Answer the following questions. 1. What term is used to describe the area where sinkholes are formed? _____________ 2. What term is used by geologists to describe the loss of surface elevation due to the removal of subsurface support? _______________________________________________ 3. What type of sinkhole can develop abruptly (over a few hours) and cause catastrophic damages? ________________________________ 4. What process displaces air spaces, making the soil impenetrable? _________________ 5. What is another term for underground mining activities? __________________________ B. Answer the following in complete sentences. 1. What could be the detrimental effects of ground subsidence to human beings and their communities? _______________________________________________________________________________________ 2. How can you personally reduce the probability of a similar scenario in Guatemala where a massive sinkhole suddenly appeared? _______________________________________________________________________________________ 3. Why is water conservation related to the lessening of human-induced ground subsidence? _______________________________________________________________________________________ 4. How does mining contribute to ground subsidence? _______________________________________________________________________________________ C. Synthesis and Evaluation Do you think mining should be stopped since it can cause ground subsidence and formation of sinkholes? Explain your answer. _______________________________________________________________________________________ _______________________________________________________________________________________ _______________________________________________________________________________________ _______________________________________________________________________________________ _______________________________________________________________________________________ _______________________________________________________________________________________ 11 Investigate on the cause and effect of ground subsidence. In groups of four to five, create a diorama-type model to simulate ground subsidence and observe its effects. You may choose the simplest materials to construct a shoebox-sized model that can be built and used for your investigation. Note that the investigation report should be submitted one week after this task is assigned. Your model should have the following: ground/soil profile or cross section of the ground from the surface to the water table or bedrock sample human community or infrastructure on its surface cause of ground subsidence From your model, make a report with the following parts: 1. Problem/Investigation Question 2. Hypothesis 3. Prediction 4. Brief background information (on what type of ground subsidence is being investigated) 5. Procedure 6. Observations/Data gathered 7. Analysis and Conclusion 8. Recommendations for real-world planning 12 Mine Subsidence Prevention: Preventing Human and Economic Costs There can be movement of ground surfaces due to the overburden of underground mine workings. This kind of ground subsidence is also known as mine subsidence. There are cases wherein the roof of an underground mine collapses, causing the ground above to subside. There are companies such as MIRECO, based in Korea, that provide services for prevention of mine subsidence. These companies provide services such as subsidence risk assessment, ground reinforcement work, and post-management throughout the lifecycle of a mine. These services can prevent damages to people and property caused by mine subsidence. Let us investigate! What kind of problems do companies such as XYZ corporation address? Why is there a need for their type of services? How does it contribute to solutions to problems involving ground subsidence? 13 How does heavy rainfall contribute to landslides? How does the public know that there is an impending hazard brought by heavy rainfall? Who are in charge of letting the public know that a heavy rainfall may be dangerous to the community? List down at least five possible effects of a five-day torrential rain brought by the Southwest monsoon or habagat to a mountainous area. How do rainfalls induce landslide? Landslides occur anytime, anywhere. The world has witnessed devastating landslides that killed and injured thousands of people, destroyed residential and business establishments, caused billions of economic disruptions and even permanently damaged the environment. Landslides also caused the displacement of thousands of people around the world. In the Philippines, there are two infamous examples of devastating hazards in modern history: the Cherry Hills Subdivision landslide in 1999 and the Guinsaugon, St. Bernard, Southern Leyte debris avalanche landslide in 2006. These two disasters brought the above-mentioned impacts of landslides to society. Although different scientists and engineers concerned with geology have varying definitions of landslide, the United States Geological Survey or USGS, one of the leading authorities regarding geological science defines landslide as the “downslope movement of soil, rock, and organic materials under the effects of gravity and also the landform that results from such movement.” 14  Fig. 1. Illustration showing the commonly used label of the parts of a landslide. Major Types of Landslides Landslides can be categorized based on the type of materials and the movement involved. 1. Fall: A fall begins when the material on cliffs or steep slopes lose support or becomes fractured from the main rock. The materials which can be rock and soil of different sizes subsequently descend by falling, bouncing, or rolling; until they reach lower or flatter surfaces. 2. Topple: A topple happens when a block of material is detached from a steep slope such as a cliff, and moves forward and downward around a point of axis (imagine a rotating motion). Toppling can occur because of the weight of the material or due to the cracks in the mass created by water or ice. Some topples can also end up as falls or slides. 15 Fig. 2. A fall (left) involves materials descending by falling, bouncing or rolling while a materials in a topple (right) move forwards and downwards around a point of axis. 3. Slide: A slide occurs when the detached mass of materials such as rocks, soil, and sometimes organic matter move along a downward sloping surface. The volume of material increases as the mass moves downwards away from its origin. When the displaced mass is moving along a concave surface, it is called a rotational landslide or slump. Otherwise, when the mass that slides down and outward along a downward sloping surface, it is called a translational landslide. Fig. 3. Mass of materials sliding in translational slide versus a slump. 16 4. Flows: A flow occurs when materials from (usually) gentle slopes are detached and flow like a viscous liquid along a surface. Debris Flow: This is a rapid movement of slurry that is informally called mudslide is formed from water that combines materials such as rocks and soil and sometimes organic matter. Lahar flow is also known as volcanic mudflow. Lahar flows originate on the slopes of volcanoes and are a type of debris flow. Lahar mobilizes the loose accumulations of tephra (the airborne solids erupted from the volcano) and related debris. Debris avalanche: This occurs from sudden collapse of unstable slopes and the fragmented debris rapidly moves downwards along the slope. In some cases, snow and ice will contribute to the movement and if a significant amount of water is present, it can become a debris flow. Fig. 4. Debris avalanche in St. Bernard, Southern Leyte in 2006 after 10 days of heavy rains and a minor earthquake (magnitude 2.6 on the Richter scale). Earth Flow: When the flow has a high amount of silt or clay, the flow becomes a more viscous earth flow. Earth flows can range from very slow and almost imperceptible creep to rapid and catastrophic. 17 4. Spreads: This occurs when the mass of soil or rocks extends or spread laterally. This mass movement of rocks and soil can usually be observed when there is liquefaction or an earthquake. Factors that Influence Landslide Development Geological factors that influence landslide include properties of rock and soil that renders them weak or sensitive to movement. For instance, weathered and fractured materials are susceptible to landslide as they are the ones that will be most easily detached from the main material. Permeability and stiffness of materials can also be factors that will make chunks of land susceptible to landslide. Morphological factors that influence landslide include the shape of land and its slope, tectonic and volcanic activities, erosion and deposition, water, the amount of vegetation on the rock and soil surface as well as the boundaries of the land mass involved. Human factors that affect landslide include development activities that modify the geological and morphological factors of the land. Mining, excavation, building of roads and dams, irrigation, and deforestation are some of the human activities that increase the susceptibility of areas to landslides. Causes of Rainfall-Induced Landslides The three main natural causes of landslide are water (rainfall), seismic, and volcanic activity. Of those three, water due to rainfall has become an increasing trend since 1980 (UNESCAP & UNISDR, 2002). Rainfall plays an essential role in the development of landslides. Slope saturation of water is one of the leading causes of landslides in the world. Water adds disturbances to steep terrain and weak geological characteristics of certain slopes. When torrential rains hit the mountainous area, it loosens soil particles and lessens the friction of the soil. Debris flow and flooding occur simultaneously during landslides. The flooding may create a landslide due to the blocking of valleys and stream channels. These blockages hold up a large deposit of water and when it collapses, flash floods will occur. The building of solid debris due to landslides may also affect the development of stream diversion and eventually creates localized erosion in other areas. Landslides occur due to natural and human-made causes. The rise in population brings a lot of factors that can contribute to landslides. New development due to urbanization and concentration of rising population may affect the weakening of once stable slopes. The 18 building of residential and commercial structures along the slopes, and its corresponding changes like drainage system, change in the surface environment, and expansion of roads can make slopes vulnerable to landslides. Infamous Incidences of Landslides in the Philippines On August 3, 1999, Cherry Hills Subdivision in Antipolo City in Rizal province suffered from a rainfall-induced landslide due to a week-long heavy rain. The amount of accumulated rainfall in the area was equivalent to a normal month-long rainfall in August. More than fifty people were instantly killed when the landslide occurred. About four hundred houses were destroyed and buried. Another devastating landslide that occurred in the Philippines happened on February 17, 2006 at Barangay Guinsaugon, St. Bernard, Southern Leyte. After a ten-day torrential rain, a massive rock slide – debris avalanche buried the whole village and killed more than one thousand people. Saturation of water in slopes is one of the leading causes of landslides in the world. When torrential rains hit the sloping areas, it loosens soil particles and lessens the friction of the soil. Signs of an Impending Landslide Landslides can be predicted to some extent, as there are observable signs of its probable occurrences. Some changes in the physical aspects of an area, be it part of man-made structures or not, can be monitored and treated as warning signs of a possible landslide. For instance, if there are cracks or bulges on concrete or paved roads and sidewalks, broken water pipes and other underground fixtures, are some issues that have been associated with major landslide events. Movement of normally fixed structures such as fences, telephone posts and other structures that are on the ground, can also be treated as signs of a possible landslide. 19  A. Answer the following questions. 1. What type of landslide is characterized by different-sized materials descending by falling, bouncing, and rolling? ___________________ 2. What type of landslide is also known as lahar? 3-5. What are the three natural causes of landslide? _____________________________________ B. Answer the following in complete sentences. 1. How does heavy rainfall cause landslides? ___________________________________________________________________________________________ 2. How do human activities influence landslide development? ___________________________________________________________________________________________ 3. What is the difference between a flow and a spread? ___________________________________________________________________________________________ 4. What is the difference between a topple and a flow? __________________________________________________________________________________________ C. Synthesis and Evaluation What suggestions can you recommend to reduce the risk of rainfall-induced landslides? __________________________________________________________________________________________ __________________________________________________________________________________________ __________________________________________________________________________________________ __________________________________________________________________________________________ After a week of consecutive thunderstorms, a landslide occurred along a mountain road in Barangay Sto. Domingo. The mountain road is a critical route in the farm-to-market transfer of the community’s products. Several weeks after the landslide incident, efforts to clear the road are still not enough to make it passable. Aside from safety and other concerns, members of the community are already raising issues that concern their economic well-being. 20 Pretend that you are an investigative journalist assigned to write about the factors that influenced the landslide incident, and the response of the community or the government. What things will you try to find out for the article you will write? Who are the people you will interview based on the roles they have in the incident? What questions will you ask to complete the details that you need for your story? Use the table below for your answers. Source of Data What/How/Why (things you (people to interview/role Questions need to find out) in the landslide or community) 21 Mitigation Measure for Landslide Hazard The Hillis Hill Landslide area is on a west-facing slope of one of the roads in Woodland, Clark County, Washington, USA. This landslide area is part of a much larger ancient landslide that extends about 365 meters along the highway, and about 600 meters upslope from the Lewis River. Landslide Technology (LT), a geotechnical firm specializing in complex landslide and rockfall evaluations and remediations, assisted Clark County with the stabilization of Hillis Hill Slide. Hillis Hill Slide investigation and repair occurred within 1997 to 2001. The process included investigation, monitoring, and design of mitigation. It was then mitigated with a horizontal drain system that was installed in 2001, and has remained intact since then. Let us investigate! Where is the landslide located? Do you think its location influenced the landslide event? Who were the most affected in the area? What measures were done after the landslide? Do you think the stabilization will ensure that no other landslide will occur in the area? If yes, explain your reasons. If no, what do you think is a more long term solution to the problem? 22 The shape of shores vary with the tides and through time due to natural causes but changes in the coastline can also be due to human activities. How can human activities and interventions contribute to coastal erosion? Think-Pair-Share: What do you think will happen when sea levels rise? List down the possible effects of a massive and global rise in the sea level along the coastal areas. What are the factors that cause and result from coastal erosion? As an archipelago, the Philippines has vast coastlines. In more than 7 000 islands, it is blessed with different types of shorelines. It has cliff shorelines particularly in Batanes, beach and barrier systems shorelines in almost all parts of the country, and salt marshes situated across the nation. Because of this natural features of the country, it is also vulnerable to a natural phenomenon called coastal erosion. Coastal erosion involves the breakdown and removal of materials from the coastline due to wave action, tidal currents, and human activities. Coastal erosion is not just a concern in the Philippines, but it is also a global issue because 15 square-kilometers of shores are retreating annually due to sea level rising and global warming. Human interventions and developments along the shores contribute to the increase of the occurrence of coastal erosion. In real estate, lots located along the shores are one of the considered prime areas. Many houses were built along the shores without proper preventive and mitigation measures to address disaster risks brought by coastal erosion. 23 Another key factor is the construction or development of tourism infrastructure along the shores such as hotels, cabins, and other amenities that contribute to the destruction of coastal zones. In January 2018, the Department of Environment and Natural Resources (DENR) was given an order to clean-up and rehabilitate Boracay island, in Malaybalay, Aklan. The particular focus of the said order was the coastal areas of the island and address improper sewerage systems of many establishments in the island. Fig. 1. The white sand beaches of Boracay island are seen as opportunities for resorts development. The coastal area are peppered with resorts and other tourist attractions. Alexey Komarov, Boracay Island, Philippines - panoramio, CC BY 3.0 Coastal erosion can be classified either as natural or anthropogenic, temporary or long-term. Temporary erosion is reversed by a period of accretion. Episodic coastal erosion occurs for example, when strong storms leave serious effects on sandy shores. Long-term erosion results from a net retreat or recession of the coastline. The sea level rise makes a long-term and permanent retreat of the coast. 24 Types of Coastal Erosion Mechanical Erosion of Waves: The mechanical action of waves is the main erosion factor in coastal environment, through high energy waves or storms waves. In low energy conditions, the erosive action of waves is reduced; however, they still contribute significantly to the removal of weathered material. Apart from removing loose material through waves, two main results are the abrasion of rock surfaces and the pressure fluctuations induced on rocks by the waves. Weathering: Coastal cliffs and intertidal coastal platforms are exposed to alternating wetting and drying of salt spray, wave swash, tides, and rain. Subsequently, they constitute suitable environment for many physical and chemical processes of weathering. Fig. 2. Coastal erosion due to weathering, sea level fluctuations and wave action. Photograph © Andrew Dunn, 04 November 2006, Happisburgh coastal erosion, CC BY-SA 2.0 25 Bioerosion: Bioerosion is the removal of rocks and minerals through the actions of organisms. The rocks and sediments in tropical regions are more susceptible to coastal erosion, due to the large biodiversity in its marine ecosystems. Marine organisms use rocks for shelter and even as a source of their own materials. For instance, limestone substrates are involved in the biochemical and biophysical processes in corals and shelled animals. A huge factor that influences the rate of bioerosion is the spatial distribution of marine organisms along the rock surface, which is largely controlled by the available moisture that largely depends on tidal currents and wave action. Mass movements: The steep slopes of rocky shores are unstable and are prone to mass movements depending on the properties and structure of its rock composition. Factors that Influence Coastal Erosion Coastal erosion is a process that is affected by natural and man-made factors. Fig. 3. A graphical representation that shows how coastal erosion is formed. 26 Climate: Climate defines the weather conditions of an area and affects physical phenomena of coastal zones such as waves, underwater currents, and storm surges. Wind regime is related to wind waves and coastal currents. The stronger the wind, the higher the wave height. Higher waves bring more erosive actions. Lithology of rocks: The hardness of the rock, its resistance to subaerial and marine erosion affect its susceptibility or resistance to weathering and erosion. A rock’s exposure to wave activities can result to the removal of base materials from the shores. Global sea level rise: It is a natural phenomenon but can be amplified by human-induced global warming due to human development activities that contribute to making the faster warming of the earth. Global warming affects the rise in sea level and contributes to the thermal expansion of ocean water, and ice sheet melting in the Polar Regions. This unprecedented sea level rise poses a threat to coastal communities and countries around the world. The main three effects of this factor are coastal erosion, flooding of wetlands, and salt contamination of coastal aquifers. Fig. 4. The map of Florida showing the rising sea level. 27 Man-made interventions: Coastal areas are a strategic location for human activities. They can be used for military bases, recreational spaces, tourist destinations, and a real estate prime land. Due to these, coastal areas become vulnerable to the effects of these human developments. Another noteworthy human activity is sand extraction that is harmful to coastal areas and its inhabitants. Coastal erosion can be natural or anthropogenic, temporary or long-term. Human interventions and developments along the shores increase the occurrence of coastal erosion. A. Answer the following questions. 1. What natural phenomenon affects the Philippines due to its being surrounded by bodies of water? ___________________________________________ 2. What is the phenomenon that involves the landward retreat of the coastline? ___________________________________________ 3. What significant factor in coastal erosion defines the weather conditions of an area and affects its physical phenomenon? ___________________________________________ 4. What factor is described as the properties of rocks that are exposed to elements? ___________________________________________ 5. What type of erosion is caused by organisms like corals and molluscs in the ocean? ___________________________________________ B. Answer the following in complete sentences. 1. How can human-induced global warming amplify rise in sea level? _________________________________________________________________________________________ 2. How do human activities and development along the coastal areas increase the occurrence of coastal erosions? _________________________________________________________________________________________ 28  3. Why is bioerosion a more significant issue in tropical regions? _________________________________________________________________________________________ 4. How does climate affect coastal erosion? _________________________________________________________________________________________ C. Synthesis and Evaluation How can we practice sustainable development in coastal areas? _________________________________________________________________________________________ _________________________________________________________________________________________ _________________________________________________________________________________________ _________________________________________________________________________________________ _________________________________________________________________________________________ _________________________________________________________________________________________ Research about the current issues in Boracay island. Create a diagram to show how activities and infrastructure in Boracay influence coastal erosion. Then, infer impacts of coastal erosion to communities, livelihood, and overall economy of Boracay island. Finally, suggest ways to mitigate coastal erosion in particular. 29 Kiribati Challenges The Republic of Kiribati located in the Central Pacific consists of 32 low-lying coral islands and one raised coral island scattered on 3.5 square kilometers of sea. Its geographical location, island characteristics, rising population and low accessibility to services make this island republic highly vulnerable to the adverse effects of climate change and natural hazards. Most of the communities and infrastructure are situated in the coast, and residents have already lost their homes because of the rising sea level and coastal erosion. Kiribati faces drought problems especially in years with La Niña years, and this means that freshwater supply can be severely rationed. Many families are unable to access freshwater supply needed for survival, daily needs, farming, and other livelihood. Environmental degradation is having severe effects on Kiribati people. Infant mortality rates due to diarrhea are the highest in the Pacific. If there will be no means for Kiribati to adapt to environmental changes, climate change and sea level rises could cause severe economic damages in Kiribati every year, and many villages in its main atoll island of Tarawa and the most outer islands are at risk of being largely submerged. Let us investigate! What are the contributing factors to the problem at hand? Who are the families that are primarily at risk ? Why does the situation need to be addressed the soonest?? What could be the impact to surrounding communities of the problem at hand? Proposed Solution: 30 Meteor showers are anticipated by people because of the beautiful display of lights in the night sky is not an everyday occurrence. Are meteors dangerous to human beings and their settlements? Think–Pair–Share: Each learner will be assigned a partner to work with. SCENARIO: Imagine a night with a once in a lifetime massive meteor shower. After visualizing a night of meteor showers, write down what happens to a meteor when it hits the ground, or what happens to the area where the meteor lands? Are objects in space considered as hazards to the Earth? Fig. 1. The trace of a brilliant fireball that was seen in the sky above the industrial city of Chelyabinsk in Russian Federation on February 15, 2013. Alex Alishevskikh, 2013 Chelyabinsk meteor trace, CC BY-SA 2.0 31 On February 15, 2013, a small industrial city in the east of the Ural Mountains, Chelyabinsk in Russian Federation was hit by flashing light from the sky. Many of its residents saw its arrival and vehicle dashboard cameras captured the moment. After a few minutes, there was a blinding light followed by a super blast that damaged thousands of houses and buildings, vehicles, and injured more than a thousand people. Initially, nobody in Russia knew what hit Chelyabinsk, and even experts were puzzled. Nuclear watchers from the United States and National Aeronautics and Space Administration (NASA) were not able to detect nuclear detonation. It was only through the uploaded videos in social networking sites and video-sharing sites that scientists finally came to know what hit Chelyabinsk. It was a superbolide from a near-earth object (NEO). Fig. 2. An infographic from the National Aeronautics and Space Administration (NASA) showing the estimate number of near-earth objects in varying sizes. Near-Earth objects (NEOs) are used to define the rocky or metallic asteroids and icy comets found between Jupiter and Mars. These near-earth objects were made from the same materials that made up the planet in the solar system, planetesimals. These materials attract 32 each other, but there are two results from this attraction, the formation of planets and destruction, that make up clouds of fragments. The area where these fragments are located is called the asteroid belt, and these fragments are orbiting the sun. Due to some disturbances, these near-earth objects, also called Mars-crossers, can move directly to the inner solar system and could hit or impact one of the inner planets. Simply speaking, these objects may hit the earth. Bolide is a generic term used to define any celestial bodies entering the earth surface, creating a fireball. Superbolide is the term used to describe a relatively larger bolide. Once a bolide hits the earth, it could explode upon impact or create a crater formation. Bolide impact depends on the features of the foreign body that enters the earth, like its size, composition, density, and its ability to survive its entry to Earth. A stony bolide can flatten the impact site without leaving a crater formation while a metallic bolide can create a vast crater. There are bolides that enter the Earth’s surface every day. Some bolides enter during the day, and the view of them are masked by the bright sunlight; others fall in the vast uninhabited land and vast oceans. It is estimated that there are eleven thousand (11, 000) bolides in the solar system and anytime, one of those may enter our atmosphere. Bolide impact is the only natural hazard that can instantly kill billions of people or destroy human properties and economic structures that could endanger the survival of civilization. Its impacts affect the geological, geophysical, and geochemical aspects of its landing area. Superbolides can have cratering formation impacts. In natural history, superbolides increased the incidence of climate change and sea level change. Intense tectonic activities, earthquakes, and increased volcanism are also linked to bolide impacts. These environmental impacts of bolides can trigger global mass extinction and global environmental dangers. Human beings, livelihood, and the environment are all exposed to this type of hazard. Though there are satellites and space telescopes that could detect a potential asteroid or comet that could hit the earth, there are still a few ways on how humans can deflect or redirect the course of a potential bolide impact. Harris, A.W., et al (2015) listed the general approach to dealing with the NEO hazard such as to search the skies for NEOs that may strike Earth. We may carry out a deflection spacecraft mission if there is sufficient time, and there is a high probability of damaging impact or evacuate or otherwise prepare to mitigate the effects of an impact. Examples of Deflection Techniques Harris, A.W., et al. (2015) suggested several ways for Earth to avoid or mitigate the impact of bolide collision. Larger NEOs such as asteroids are hoped to be avoided by either reducing its 33 size, its speed, or changing its direction to avoid collision completely. Technologies suggested that can meet those objectives include using a laser beam to move the NEO; using large lenses or mirrors to refocus sun’s energy on an NEO, and using another object to collide with an NEO to deflect it or change its velocity. Experimental missions are being done by space agencies to prepare for bolide hazards. NASA Deep Impact mission successfully caused an impactor to collide with the nucleus of Comet 9P/Tempel 1 on July 4, 2005. Due to the large mass of the 6-km-diameter nucleus, and non-gravitational forces acting on it, it was not possible to measure a change in the comet’s trajectory resulting from the impact. Nevertheless, the mission successfully impacted its target and highlighted the complex autonomous guidance necessary to do so. Fig. 3. Artist's concept of Deep Impact from National Aeronautics and Space Administration (NASA) Deep Impact Mission in 2005. 34  Due to some disturbances, NEO can move to the inner solar system and impact one of the inner planets such as Earth. The whole planet is exposed to bolide hazards. A. Answer the following questions. 1-2. Give two examples of Near Earth Objects (NEOs).____________________________________ 2. What is the generic term used to define any celestial body entering the earth’s surface? ___________________________________________ 3. What are the rocky or metallic asteroids and icy comets found between Jupiter and Mars? ___________________________________________ 4. What does NASA stand for? __________________________________________________________ B. Answer the following in complete sentences. 1. What is the difference between a bolide and a NEO? ___________________________________________________________________________________________ 2. How will an average-sized bolide affect the environment of its landing area? ___________________________________________________________________________________________ 3. How should the governments of the world work together to address the threats of a bolide impact? ___________________________________________________________________________________________ 4. How can one bolide affect the whole planet? Cite an example of a scenario. ___________________________________________________________________________________________ 35  C. Synthesis and Evaluation What innovation can you share to eliminate all hazards coming from the asteroid belt? ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ With four other group mates, investigate the factors that cause impact craters from bolides. Design your own experiment and share your results in class at most a week after this task is assigned. Choose at least four of the following variables in your test: size, shape, mass, distance from point of impact, angle, depth of impact crater, type of landing area (solid ground, sand, water). Present your experiment following the outline below: I. Problem II. Hypothesis III. Materials and Methods IV. Variables V. Experiment Procedure VI. Analysis of Results VII. Conclusion and recommendations 36 NEOSSat: Canada's Sentinel in the Sky The Near-Earth Object Surveillance Satellite (NEOSSat), launched February 25, 2013, is the latest Canadian satellite. It is the world's first space telescope dedicated to detecting and tracking asteroids and satellites. NEOSSat circles Earth every 100 minutes, scanning space near the Sun to pinpoint asteroids that may someday pass close to the planet. NEOSSat also operates to monitor satellites and space debris as part of Canada's commitment to keeping our orbital space safe for the whole planet. NEOSSat applies the kind of technology for which Canada has already demonstrated in its very successful Microvariability and Oscillations of Stars (MOST) satellite. Let us investigate! What is the technology being introduced in this case? Where was it launched? When was it launched? Who are the ones responsible for the technology? What is the purpose of the said technology? Impact or effects of the said technology on disaster-preparedness? 37 Beach Patrol The goal is to contribute to an awareness campaign regarding hazard awareness and disaster preparedness of a civic organization. You will be part of a five - member team of student- researchers assigned to know about the lives of people living along the coastline or riverbank. Your team will develop a storyboard that will be used for a digital infomercial as part of the organization’s campaign. Your group has to interview one (1) person who has been residing near or in the coastline or riverbank for at least ten (10) years. In your interview you need to ask the following questions: How long have you been residing in the area? Can you share some of your experiences residing here in the coastline or riverbank? What are the benefits of living in this area? Are there problems you encounter that are related to your location or the general features of the area? If yes, please elaborate. How are you affected and how do you manage during the typhoon or habagat season? Do you see any changes in the coastline/riverbank as time goes by? Did the water along the coast/river rise or recede in the last ten years? Are there things you want to change along the coastline or riverbank of your community? Are there messages you want to send to the government? If so, please elaborate. You will be given a month from the date of assignment, to finish the data-gathering and the storyboard. You will present and submit your data report and your storyboard. 38 Your output will be rated according to the following rubric: Criteria Accomplished Developing Beginning (12-15 points) (6-11 points) (0-5 points) CONTENT complete data, able almost complete to there are none to to include correct complete data, able to minimal concepts in analysis of the include some concepts the data or the coastline situation in geological hazards storyboard that are from concepts in in the storyboard but related to geological geological hazards as with minimal analysis hazards reflected in the storyboard STRUCTURE has a cohesive story has a beginning, body, needs some revisions with clear theme, and ending but lacks in structure to gain beginning, body and seamless story cohesion ending STORYBOARD can capture can capture audience’s images hardly depict a PRESENTATION audience’s interest interest; not easy to story, plot and flow positively; easy to understand story flow needs revision understand story flow 39 Please put check if you can do the following statements: Check I can…...discuss the different geologic hazards....analyze the causes of geologic hazards....recognize signs of impending geological hazards....interpret geologic maps....apply mitigation strategies to prevent loss of lives and properties. Reflect I find __________________________ the most interesting because ______________________. I got ____ checks because _______________________________________________________. I need to improve on _______________________because _____________________________. I need to practice _________________________ because _____________________________. I plan to _____________________________________________________________________. 40  Over extraction or withdrawal of underground materials including fluids (groundwater, petroleum, and geothermal) can trigger ground subsistence. Human activities, development, and infrastructures can affect the occurrence of landslides. Climate defines weather conditions of an area and affect physical phenomenon of coastal zones such as waves, underwater currents, and storm surges. Wind regime is related to wind waves and coastal currents. Any near-earth object has the potential to impact the earth and can cause loss of or damage to human lives and properties. 41 Aurelio, M.A., Dianala, J.B., Tan, C.M., 2017: Senior High School Disaster Reduction and Management – Reader. First Edition. Department of Education, Bureau of Learning Resources. Pasig City. Philippines Aghai, A.K., 2015:Survey of land subsidence – case study: The Land Subsidence Formation in Artificial Recharge Ponds at South Hamadan Power Plant, northwest of Iran J. Earth Syst. Sci. 124, No. 1, February 2015, pp. 261–268 Indian Academy of Sciences" Bird, E. L., 2015: Beach Nourishment. Springer Davidson-Arnott, R., et al., 2011: Coastal Erosion and Climate Change "EARTH FISSURES." Earth Fissure Mitigation Tips. Accessed April 02, 2018. http://data.azgs.az.gov/hazard-viewer/mitigation/fissures.html. Evelpidou, N., 2015. Coastal Erosion. National and Kapodistrian University of Athens Flentje, P., & Chowhury, R., 2002: Uncertainties in Rainfall-Induced lLandslide Hazard. Quarterly Journal of Engineering Geology and Hydrogeology. Geological Society of London Government of Canada, Canadian Space Agency. "NEOSSat: Canada's Sentinel in the Sky." Canadian Space Agency Website. March 25, 2015. Accessed April 02, 2018. http://www.asc-csa.gc.ca/eng/satellites/neossat/. Grady, M.M., et al., 1998: Meteorites: Flux with Time and Impact Effects. Geological Society London, Special Publications Harris A. W., Boslough M., Chapman C. R., Drube L., Michel P., and Harris A. W. (2015) Asteroid impacts and modern civilization: Can we prevent a catastrophe? In Asteroids IV (P. Michel et al., eds.), pp. 835–854. Univ. of Arizona, Tucson Hedge, A.V., 2010: Coastal Erosion and Mitigation Methods - Global State of Art. Indian Journal of Geo-Marine Sciences Kaiho, K., et al., 2001: End-Permian Catastrophe by Bolide Impact: Evidence from A Gigantic Release of Sulfur from the Mantle. Geological Society of America 42 "Kiribati: Kiribati Adaptation Program - Phase III." World Bank. Accessed April 02, 2018. http://www.worldbank.org/en/results/2011/09/15/kiribati-adaptation-program-phase-3. Landslide Technology :: Representative Rockfall Projects. Accessed April 02, 2018. http://www.landslidetechnology.com/rockfall.htm. Ljungdahl, A., 2015: Analysis of Groundwater. Department of Earth Science, University of Gotenburg level changes and land subsidence in Gothenburg, SW Sweden" NERC. British Geological Survey Website - Page Not Found. Accessed April 02, 2018. http://www.bgs.ac.uk/research/climatechange/environment/coastal/home.html. Plani. MIRECO. Accessed April 02, 2018. http://www.mireco.or.kr/board?menuId=MENU00845&siteId=null. Popescu, M.E. & Sasahara, K. (nd) Engineering Measures for Landslide Disaster Mitigation Saunders, A. D., White, R.V., 2005: Volcanisms, Impacts and Mass Extinctions: Incredible Credible Coincidences?. Elsevier, Science Direct, Lithos Glossary Aquifer – porous and permeable rock that holds water Asteroid - rocky and metallic objects that orbit the sun, but are too small to be called planets; most of which are concentrated in the region between Mars and Jupiter called asteroid belt Avalanche - mass of materials rapidly moving down a slope Coastal erosion – is the removal of material from the coast by wave action, tidal currents, and/or activities of man, typically landward retreat of the coastline. It can also be seaward and alongshore movement of the coast Debris - loose materials such as broken pieces of rocks Drought - prolonged absence of precipitation (rain) Erosion - removal and transport of weathered materials 43 Fissure – cracks in the ground that are formed as a result of ground subsidence Ground subsidence - is the loss of surface elevation due to the removal of subsurface support Landslide – is the “downslope movement of soil, rock, and organic materials under the effects of gravity and also the landform that results from such movement” Near-earth objects (NEOs) – are used to define generally the rocky or metallic asteroids and icy comets found between Jupiter and Mars Sinkhole - hole in the ground usually caused by ground subsidence in karst terrain 44  Answers to Check Your Understanding Lesson 1: Ground Subsidence A. 1. karst terrain 2. ground subsidence 3. cover-collapse sinkholes 4. compaction 5. subterranean B. 1. examples include damaged infrastructures, injuries, fatalities 2. examples include use water wisely so as not to contribute to overdraining of aquifers 3. overdraining of groundwater can cause ground subsidence and possible formation of sinkholes 4. mining causes reduction in materials that serve as subsurface support C. Possible answer: Mineral resources are used for many industrial and consumer products so they are essential to society. However, planned mining prioritizing only essential resources and taking environmental safety and sustainability as major considerations can lessen negative effects of mining including ground subsidence. Lesson 2: Rainfall-Induced Landslide A. 1. fall 2. volcanic mudflow 3-5. (any order) water, seismic, volcanic activity B. 1. Possible answer: Slope saturation of water loosens the soil particles and lessen the friction of the soil. 2. Possible answer: Human activities modify geomorphology of the land and some of those changes (e.g. mining, deforestation, etc.) increase the susceptibility of areas to landslides. 3. Flow involves downward movement of viscous materials while spread involves extending of mass of land laterally. 4. Topple involves forward and downward movement while fall involves downward movement through falling, bouncing, or rolling. 45 C. 1. Sample answer: The Government must implement a strong policy on migration/relocation of people living within and close to landslide prone areas. Policies on minimal disturbance of areas with steep slopes can also be something to explore. Lesson 3: Coastal Erosion A. 1. rising sea level 2. coastal erosion 3. global warming 4. lithology of rocks 5. bioerosion B. 1. Human activities such as sand extraction that is harmful to coastal areas and its inhabitants. 2. The development of tourism infrastructure along the shores such as hotel, cabin, and other amenities contributes to the destruction of coastal zones. 3. Tropical region is where marine biota is abundant. 4. Winds, wave action, sea level, and temperature are factors of coastal erosion that are influenced by climate. C. 1. Proper sewage system that adheres to the environmental law and development of renewable source of energy can help in sustainable development in coastal areas. Lesson 4: Bolide Impact A. 1 and 2. (any order) asteroid, comet 3. bolide 4. Near-earth objects 5. National Aeronautics and Space Administration B. 1. Bolides are bodies from space most probably from NEOs, that enter Earth. NEOs are space bodies that are normally found in the asteroid belt but can sometimes move towards the inner solar system. 46  2. The impact of bollides on its landing area depends on many factors including its characteristics (e.g. size, shape, speed, composition, mass, etc.) and the characteristics of the landing area. 3. They should keep open communication and coordinate their DRRM efforts with all the other countries. 4. A bolide with enough energy to influence or cause other geological, hydrological, atmospheric, and biological hazards can affect the whole planet. Ex. the impact can trigger volcanic eruptions and consequently change the earth’s atmospheric composition and condition. C. Possible answers include existing or perceived future technology that can reduce asteroid size or change asteroid’s velocity or trajectory. 47