Geophysical hazards Flashcards
What are geophysical hazards and what processes do they encompass?
Geophysical hazards refer to natural events resulting from the Earth’s internal processes. These include earthquakes, volcanic eruptions, and mass movements such as landslides, rockslides, debris flows, and mudflows. These hazards can have devastating impacts on human life, infrastructure, and the environment.
Describe the eruption of Mount Marapi on December 3, 2023. What were its effects?
On December 3, 2023, Mount Marapi erupted on the Indonesian island of Sumatra, producing an ash plume that reached heights of 3,000 meters. The eruption deposited significant amounts of volcanic ash in surrounding districts, leading to the tragic death of twenty-three hikers found near the volcano’s crater. This event highlights the dangers associated with volcanic activity in populated areas.
What are the three types of tectonic plate boundaries and their associated geological activities?
- Converging Boundaries: Tectonic plates move towards each other (→ ←), causing intense geological activity such as earthquakes and volcanic eruptions due to subduction or collision.
- Divergent Boundaries: Plates move apart (← →), leading to the formation of new crust through volcanic activity and frequent earthquakes as magma rises to fill the gap.
- Transform Boundaries: Plates slide past each other horizontally (↔), primarily resulting in earthquakes without significant volcanic activity.
What recent seismic activity has been observed in Iceland and its implications?
Since October 24, 2023, Iceland has experienced a series of earthquakes on the Reykjanes peninsula, indicating a high probability of an impending volcanic eruption. Evacuations have occurred in anticipation of potential hazards. The Fagradalsfjall volcano has erupted three times since 2021, creating new landscapes known as cooling craters.
Explain the structure of the Earth and its geological history.
The Earth consists of three main layers: a solid inner core made primarily of nickel and iron, a semi-solid mantle composed of molten rock, and a thin solid crust where humans reside. The crust is comparable in thickness to a piece of paper relative to the entire planet’s size. The first land masses emerged around 2.5 billion years ago, with Pangea forming later as a supercontinent. The movement of tectonic plates driven by superheated magma continues to shape Earth’s surface.
What types of volcanoes exist and what are their characteristics?
- Shield Volcanoes: Broad and gently sloping; formed by low-viscosity basaltic lava that flows easily over great distances (e.g., Mauna Loa in Hawaii).
- Composite Volcanoes (Stratovolcanoes): Steep-sided and characterized by alternating layers of lava flows and ash; often associated with explosive eruptions (e.g., Mount St. Helens).
- Cinder Cone Volcanoes: Smallest type; built from ejected lava fragments that solidify before falling to the ground; typically have steep slopes (e.g., Paricutin in Mexico).
What are primary and secondary hazards associated with volcanic eruptions?
Primary hazards include:
- Lava Flows: Molten rock that erupts from a volcano; can destroy everything in its path but moves slowly enough for evacuation in many cases.
- Ash Fall: Volcanic ash can travel hundreds of kilometers from the eruption site, causing respiratory issues for humans and animals, damaging crops, and collapsing roofs.
- Volcanic Gases: Emissions such as carbon dioxide and sulfur dioxide can be hazardous to health and contribute to climate change.
Secondary hazards include:
- Lahars: Mudflows formed when volcanic ash mixes with water from rainfall or melting snow; they can travel rapidly down river valleys.
- Rock Avalanches: Occur when volcanic structures collapse due to instability; can cause significant destruction.
Describe different types of magma and their implications for volcanic eruptions.
- Basaltic Magma: Forms at constructive boundaries; low viscosity allows for fluid lava flows; results in less explosive eruptions.
- Andesitic Magma: Intermediate silica content leads to moderate viscosity; can cause explosive eruptions.
- Rhyolitic Magma: High silica content results in high viscosity; often leads to highly explosive eruptions due to trapped gases.
Magma composition influences eruption style: basaltic eruptions tend to be less violent compared to rhyolitic eruptions.
What is liquefaction during an earthquake? Provide an example.
Liquefaction occurs when saturated soil loses its strength due to shaking during an earthquake, behaving like a liquid rather than solid ground. This phenomenon can lead to buildings sinking or tilting dangerously. A notable example is the Christchurch earthquake on February 22, 2011, where liquefaction caused extensive damage to infrastructure.
How do human activities contribute to geophysical hazards? List specific activities and their impacts.
Human activities such as mining disturb geological structures, while dam construction adds weight to faults that may trigger seismic events. Fracking increases seismicity by injecting high-pressure fluids into rock formations, altering stress levels in faults. Urbanization can also lead to increased runoff and erosion that destabilizes slopes.
What are the characteristics and impacts of lava flows as a primary volcanic hazard? Provide an example.
Lava flows are molten rock that erupts from a volcano and can travel several kilometers from the vent, depending on the viscosity of the magma. Basaltic lava flows are typically less viscous and can move at speeds up to 40 km/h. While they can destroy buildings and infrastructure, they usually move slowly enough to allow for evacuation. A significant example occurred during the 2014-2015 eruption of Kilauea in Hawaii, where lava flows threatened the town of Pahoa, causing evacuations and property damage
Describe pyroclastic flows and their associated risks. Include a historical example.
Pyroclastic flows are fast-moving currents of hot gas, ash, and volcanic rock that can reach speeds of up to 700 km/h and temperatures exceeding 600 °C. They are among the deadliest volcanic hazards due to their speed and density, capable of incinerating everything in their path. A historical example is the eruption of Mount Vesuvius in 79 AD, which buried the cities of Pompeii and Herculaneum under pyroclastic material, resulting in thousands of deaths.
What are the effects of ash fall as a primary volcanic hazard? Provide an example of its impact.
Ash fall consists of fine particles ejected during an eruption that can blanket large areas, leading to respiratory issues, damage to crops, and structural collapse due to weight accumulation on roofs. The 2010 eruption of Eyjafjallajökull in Iceland produced an ash cloud that disrupted air travel across Europe for several weeks, affecting millions and causing significant economic losses.
Explain volcanic gas emissions as a primary hazard and provide a notable incident.
Volcanic gases such as carbon dioxide, sulfur dioxide, and hydrogen sulfide can be released during eruptions, posing health risks to humans and animals. In extreme concentrations, these gases can lead to fatalities. A tragic incident occurred at Lake Nyos in Cameroon in 1986 when a sudden release of carbon dioxide from the lake suffocated approximately 1,700 people and thousands of livestock in nearby villages.
What are lahars, how do they form, and what is a significant example?
Lahars are volcanic mudflows created when volcanic ash mixes with water from rainfall or melting snow/ice. They can flow rapidly down river valleys, causing destruction far from the volcano. An example is the lahars generated by the eruption of Mount Pinatubo in the Philippines in 1991, which caused extensive damage to surrounding communities and infrastructure.
Describe jökulhlaups and their consequences with an example.
Jökulhlaups are glacial outburst floods that occur when volcanic eruptions beneath glaciers melt large volumes of ice rapidly. These floods can sweep away everything in their path. A notable instance was during the 2010 Eyjafjallajökull eruption in Iceland when melting ice caused jökulhlaups that destroyed roads and bridges.
What is acid rain resulting from volcanic eruptions? Provide an example of its effects.
Acid rain forms when sulfur dioxide emitted during an eruption reacts with water vapor in the atmosphere to create sulfuric acid. This can damage crops, forests, aquatic ecosystems, and infrastructure. An example is the acid rain resulting from the eruption of Mount St. Helens in Washington State in 1980, which adversely affected local agriculture and water quality.
How do landslides relate to volcanic activity? Provide a historical case study.
Landslides can occur due to volcanic activity when unstable slopes fail under the weight of accumulated ash or during explosive eruptions. They can also transform into lahars if water is involved. The Mount St. Helens eruption in May 1980 triggered massive landslides that devastated over 600 km² of forested land. These flashcards provide detailed information on various hazards associated with volcanic activity while including historical examples for better understanding and context.
What is the significance of the Earth’s crust and its relationship to human habitation?
The Earth’s crust is the outermost layer where humans live, and its thickness is comparable to that of a piece of paper relative to the entire planet. Beneath the crust lies the molten mantle, which cannot be accessed by humans due to extreme temperatures that would incinerate any material. The crust’s stability is crucial for human settlements, as geological processes beneath can lead to hazards like earthquakes and volcanic eruptions.
How does the movement of tectonic plates drive geological changes?
The movement of tectonic plates, driven by superheated magma from the mantle, causes shifts in land masses over geological time. Approximately 220 million years ago, these movements shaped the current configuration of continents. Evidence of this movement is seen in similar fossil records across different continents, indicating that they were once connected.
What types of seismic waves are generated during an earthquake? Describe their characteristics.x
- Primary Waves (P-waves): Fastest seismic waves, traveling through solids and fluids; characterized by alternating compressions and dilations.
- Secondary Waves (S-waves): Slower than P-waves, only travel through solids; involve transverse motion perpendicular to wave direction.
- Love Waves: Surface waves causing horizontal shaking; largest amplitude at the surface.
- Rayleigh Waves: Cause elliptical rolling motion similar to ocean waves; penetrate deeper but have lower speed than Love waves.
What factors increase a slope’s susceptibility to mass movement?
Several factors contribute to slope instability:
- Water: Increases weight and acts as a lubricant for materials.
- Erosion Processes: Coastal or river erosion can weaken slopes.
- Gradient of Slope: Steeper slopes are more prone to failure.
- Rock Type: Soft rocks like mudstone are more susceptible than hard rocks like limestone.
- Vegetation Removal: Lack of vegetation reduces soil stability as roots help anchor sediments.
How do human activities contribute to geophysical hazards? Provide specific examples.
Human activities such as mining can destabilize geological structures, while urbanization alters natural drainage patterns, increasing flood risks. For instance, dam construction adds significant weight to fault lines, potentially triggering earthquakes. Fracking has been linked to increased seismic activity due to high-pressure fluid injections into rock formations.
How does water influence slope stability and contribute to mass movement?
Water adds weight to the materials on a slope, increasing the overall load and reducing the frictional resistance that holds the slope together. When water saturates the soil, it can lead to a significant decrease in shear strength, making it easier for materials to slide downwards. Additionally, water can create hydrostatic pressure within soil layers, which destabilizes them further. For example, heavy rainfall can trigger landslides by saturating the ground, as seen during intense storms in regions like California.
What role does erosion play in increasing slope susceptibility to landslides?
Erosion processes, such as those caused by rivers or coastal waves, can undercut the base of a slope, making it steeper and less stable. Continuous erosion removes support from the bottom of slopes, leading to an increased likelihood of failure. For instance, coastal erosion along cliffs can lead to significant landslides during storms or high tides.
Explain how the steepness of a slope affects its susceptibility to mass movement.
The angle of a slope is critical; steeper slopes have a higher gravitational force acting on them, which increases the potential for mass movement. Any alteration that increases steepness—such as road construction or natural erosion—can lead to instability. For example, landslides are more common on slopes exceeding 30 degrees because gravity exerts a stronger pull on loose materials.
How does rock type and structure influence slope stability?
Different types of rocks have varying degrees of resistance to weathering and erosion. Soft rocks like mudstone are more susceptible to failure compared to hard rocks like granite. The arrangement of rock layers also matters; impermeable layers can trap water above them, leading to increased pore pressure and potential sliding. For instance, landslides often occur in areas with sedimentary rock formations that are easily eroded.
What impact does vegetation have on slope stability?
Vegetation plays a crucial role in stabilizing slopes by anchoring soil with root systems, reducing erosion, and absorbing excess water. The removal of vegetation—due to deforestation or wildfires—can significantly increase susceptibility to mass movement by destabilizing the soil structure. For example, areas affected by wildfires often experience increased landslide activity during subsequent rain events due to loss of root support.
How do human activities contribute to increased mass movement risks?
Human activities such as construction, mining, and land clearing can destabilize slopes by altering natural drainage patterns and increasing weight on vulnerable areas. For instance, grading roads on steep hillsides can create unstable conditions that lead to landslides during heavy rainfall or seismic activity. Urbanization often leads to increased runoff and reduced vegetation cover, further exacerbating the risk.
What is social vulnerability and what factors contribute to it?
Social vulnerability refers to the inability of individuals, organizations, and societies to withstand adverse impacts from hazards due to inherent characteristics of social interactions, institutions, and cultural values. It is linked to the well-being of individuals and communities and includes aspects such as literacy levels, education, peace and security, access to basic human rights, good governance, social equity, positive traditional values, customs, ideological beliefs, and collective organizational systems. For example, during flooding events, vulnerable groups such as children, the elderly, and people with disabilities may struggle to protect themselves or evacuate.
How does economic vulnerability affect disaster resilience? Provide an example.
Economic vulnerability is determined by the economic status of individuals and communities. Poorer populations are more susceptible to disasters because they often lack resources to build resilient structures or implement protective measures. For instance, families living in squatter settlements may be unable to afford housing in safer areas, making them more vulnerable to hazards.
What constitutes environmental vulnerability? Provide an example.
Environmental vulnerability involves natural resource depletion and degradation. Key aspects include the sensitivity of ecosystems to external pressures such as pollution and climate change. For example, wetlands like the Caroni Swamp are vulnerable to increasing salinity from seawater intrusion and pollution from stormwater runoff containing agricultural chemicals.
What is the Pressure Release Model in understanding vulnerability?
The Pressure Release Model identifies a progression of vulnerability based on root causes at the macro scale—such as economic development, infrastructure, and governance—coupled with dynamic pressures that impose limitations on society. For instance, rural poverty may drive migration to cities, overwhelming urban resources and leading to informal housing in hazardous locations. This can result in social unrest during crises due to a lack of community cohesion and effective governance.
What trends indicate increasing vulnerability to natural hazards in the future?
Despite improvements in disaster forecasting and building resilience, trends suggest that vulnerability may increase due to factors like an aging population and rapid urbanization near coastlines. For example, assessments indicate a 2 in 3 chance of a magnitude 6.7 or larger earthquake occurring in California’s San Francisco Bay area within the next 30 years.
How do geographical factors influence vulnerability to natural hazards?
Geographical factors play a crucial role in determining risk levels associated with natural hazards. Areas prone to multiple hazards—such as the Philippines with its typhoons, volcanoes, and earthquakes—experience heightened vulnerability due to their environmental conditions. Additionally, low-lying regions like Bangladesh are more susceptible to flooding due to high rainfall or snowmelt.
What defines a disaster according to geophysical hazards?
A disaster occurs when a hazard impacts a vulnerable population resulting in at least 10 fatalities and affecting over 100 individuals while prompting requests for international assistance.
List factors that affect geophysical hazard impacts.
Factors influencing geophysical hazard impacts include:
- Time of Day: The timing of an event can affect population exposure; for example, nighttime earthquakes may catch people unprepared.
- Degree of Isolation: Remote locations may face challenges in receiving timely aid.
- Slope: Steep slopes can exacerbate landslide risks.
- Location: Proximity to coastlines increases tsunami risk.
- Soil Type: Certain soil types are prone to liquefaction during earthquakes.
What factors contributed to the risk during the 2004 Indian Ocean tsunami?
Key factors included low altitude where most of the population lived at sea level, making them highly vulnerable when the tsunami struck. The direction of the wave also played a critical role in determining impact severity.
Describe physical factors influencing risk during the Nyiragongo eruption in 2021.
The slope gradient facilitated lava flow downhill through populated areas. The presence of valleys affected lava movement patterns, while locations of volcanic plumes influenced where lava would travel.
What physical factors contributed to risk during the Haiti earthquake in 2010?
The slope gradient influenced building stability; vegetation loss increased susceptibility; liquefaction was exacerbated by proximity to water bodies; and high groundwater levels further destabilized structures during shaking.
Explain how local geographical factors impact vulnerability during natural hazards.
Local geographical factors such as topography significantly influence risk levels from hazards. For instance:
- Steep unconsolidated soils are more prone to landslides.
- Low coastal plains are at risk from tsunamis.
- Sand-based sediments are susceptible to liquefaction.
What is the relationship between urbanization and vulnerability to natural hazards?
Urbanization can exacerbate vulnerability as rapid population growth in cities often leads to informal housing in hazardous areas. This migration can overwhelm city resources, resulting in inadequate infrastructure and services. For example, new arrivals in urban areas may lack social networks, leading to isolation and increased risk during crises.
How does the timing of a disaster impact its effects on a population? Provide an example.
The timing of a disaster can significantly influence its impact. For instance, the L’Aquila earthquake in Italy occurred at 3:32 AM when most residents were asleep, limiting their ability to respond quickly. If the earthquake had struck during the school day, it is believed that the casualties would have been much higher due to vulnerable school infrastructure.
What geographical factors influenced the response to the 2009 L’Aquila earthquake?
L’Aquila benefited from its proximity to Rome, allowing for a rapid mobilization of emergency services and resources. The quick response included establishing temporary shelters and initiating search and rescue operations within hours of the earthquake.
Describe the challenges faced by remote areas during natural disasters using Greenland as an example.
In June 2017, a landslide in Nugaatsiaq, Greenland, caused a tsunami that washed away houses and resulted in fatalities. The remote location posed significant challenges for response efforts due to sparse population, limited local resources, and difficult access for boats or vehicles. The municipality’s vast geographical area made timely aid delivery extremely challenging.
What were the impacts of the 2015 Nepal earthquake on infrastructure and humanitarian response?
The 7.9 magnitude earthquake in Nepal caused extensive destruction of infrastructure, with many areas becoming inaccessible by road. Humanitarian agencies faced logistical challenges in delivering aid due to damaged roads and landslides. Emergency response units were deployed via helicopter to remote locations like Rasuwa, where local hospitals were severely impacted.
How do local geological factors affect vulnerability during geophysical hazards?
Local geological factors such as soil type, slope gradient, and topography play critical roles in determining vulnerability. For example, steep unconsolidated soils are more likely to fail during heavy rainfall or seismic activity, while low-lying coastal areas are at higher risk from tsunamis due to their elevation relative to sea level.
What were the consequences of the Nyiragongo eruption for the city of Goma?
The Nyiragongo eruption resulted in significant destruction within Goma, with approximately 15% of the city’s buildings destroyed by lava flows. The airport was heavily impacted, losing two-thirds of its operational capacity. The chaotic evacuation led to approximately 120,000 people becoming homeless as they fled the advancing lava.
What secondary health hazards arose after the Nyiragongo eruption?
Following the Nyiragongo eruption, secondary health hazards included outbreaks of diseases such as malaria and cholera. However, due to a pre-existing presence of humanitarian agencies in the region due to ongoing conflict, these outbreaks were largely mitigated.
Discuss how the Eyjafjallajökull eruption affected global air travel and economy.
The Eyjafjallajökull eruption led to a massive ash cloud that disrupted air travel across Northern Europe for six days. This closure affected approximately 5 million travelers worldwide and resulted in an estimated loss of $200 million per day for the aviation industry. Additionally, sectors reliant on timely shipping—such as fresh produce and pharmaceuticals—faced significant supply chain disruptions.
What are the characteristics and hazards associated with the stratovolcano eruption in the Democratic Republic of Congo on July 4th?
The eruption occurred in a region characterized by fractures of tectonic plates and constant seismic activity related to the East African Rift between the Nubian and Somalian plates. The steep nature of the volcano led to rapid lava flows, exacerbating hazards. Vulnerabilities included low-income communities (LIC) with weak hazard protection and inadequate infrastructure.
What were the impacts of the stratovolcano eruption in the Democratic Republic of Congo?
The eruption resulted in 197 fatalities and left 24,000 children out of school. In response to the disaster, schools and communities established evacuation processes for emergencies. Employment rates surged from 80% to 95%, while acid rain caused by volcanic gases led to agricultural losses and contaminated drinking water. The World Health Organization (WHO) provided vaccines during a measles outbreak following the eruption.
Describe the Eyjafjallajökull eruption, including its geological context and primary hazards.
Eyjafjallajökull is a shield volcano located at a divergent plate boundary between the Eurasian and North American plates along the Mid-Atlantic Ridge. The primary hazard was an ash cloud generated by explosive interactions between hot magma and glacial water.
What secondary hazards arose from the Eyjafjallajökull eruption?
Secondary hazards included glacial outburst floods, lahars (volcanic mudflows), and rockslides resulting from melting ice interacting with volcanic activity
What vulnerabilities were present during the Eyjafjallajökull eruption?
High preparedness characterized this event, with numerous volcanic researchers monitoring activity. They detected small earthquakes leading up to the eruption. Temporary Internally Displaced Persons (IDP) shelters were established for 800 individuals, and families were well-prepared for evacuation.
What were the economic impacts of the Eyjafjallajökull eruption?
The aviation industry lost approximately $200 million per day due to flight cancellations caused by the ash cloud. The total cost to Iceland for managing the eruption’s impacts was estimated at $7.5 million. The Icelandic Red Cross registered all inhabitants in nearby areas within two hours, providing accommodation and support during a declared state of emergency.
What were the causes of the Guinsaugon landslide in the Philippines?
The Guinsaugon landslide was triggered by heavy rainfall from typhoons, deforestation practices such as slash-and-burn methods, and a small earthquake with a magnitude of 2.6. The mountainous terrain contributed to instability.
Discuss vulnerabilities associated with the Guinsaugon landslide.
Landslides frequently occur in this region; however, residents were unprepared for such an event. The landslide struck a rural area, complicating aid delivery efforts due to difficult access.
What were the impacts of the Guinsaugon landslide?
The landslide resulted in 1,126 deaths over a 4 km area, widespread vegetation destruction, soil erosion, and contamination of water supplies. International aid focused on repairing structures, building new houses for affected families, reforestation efforts, and establishing emergency care through field hospitals.
What factors contributed to the Mocca mudflow disaster?
The Mocca mudflow was caused by heavy rainfall (130 mm), flash flooding, landslides, overflowing rivers (Mocoa, Sangoyaco, Mulatto), steep relief, and ineffective land management policies. Mass deforestation exacerbated vulnerability by removing roots that stabilize land.
What vulnerabilities were present during the Mocca mudflow disaster?
Warnings had been issued for years about flooding risks due to proximity to rivers; however, relocation was difficult due to migrant workers and those fleeing guerrilla activities.
What were the impacts of the Mocca mudflow disaster?
The disaster resulted in an estimated 300-100 deaths, with around 400 injured and 200 missing. Neighborhoods along rivers were devastated, families were separated, and essential infrastructure such as roads and hospitals was damaged. The power supply was severely impacted (85% damaged), leading to declines in tourism and loss of industrial and agricultural activity.
What trends are observed in significant earthquakes from 1932 to 2017?
The trend shows an increase in the number of significant earthquakes over time. In 1932, fewer countries experienced significant earthquakes, while by 2017, countries such as India and Mozambique were affected. For example, Iran’s seismic activity level increased from level 1 in 1932 to level 5 in 2017.
What trends are observed in significant volcanic eruptions from 1818 to 2017?
The trend indicates an increase in significant volcanic eruptions over time. In 1818, significant eruptions were limited to Mexico at level 1. By 2017, eruptions occurred in multiple countries, including Italy, Indonesia, and Malaysia at level 4. Notably, no significant volcanic eruptions were reported in Mexico in 2017.
Why is there an apparent increase in earthquakes and volcanic eruptions?
The increase in reported earthquakes and volcanic eruptions is attributed not to a rise in actual occurrences but rather to improved monitoring and reporting technologies that enhance data collection and awareness of these events.
What does the graph showing natural disasters from 1970 to 2019 reveal?
The graph indicates an overall increase in natural disasters over time. While there is an increase in reported earthquakes and volcanic eruptions due to better reporting, landslide occurrences have risen significantly, likely linked to extreme weather events, population pressure, and land-use changes.
What does the graph depicting global annual deaths from natural disasters by decade illustrate?
The graph shows a rapid decrease in deaths from natural disasters since the early 1900s. Initially, droughts and floods caused the most fatalities from the 1920s to the 1960s; however, earthquakes have since become the leading cause of death despite not showing a consistent pattern of increase.
How has population growth influenced earthquake-related deaths?
The trend of increased deaths from earthquakes correlates with population growth. Between 1975 and 2015, the number of people living in seismic areas rose by 93%, increasing exposure to earthquake hazards as urban populations concentrated in vulnerable regions.
What are the implications of living near dangerous volcanoes?
In 2015, over 400 million people lived near one of the world’s most dangerous volcanoes. This proximity heightens their exposure to potential eruptions and associated hazards.
Describe the relationship between population density and earthquake risk.
Areas with high population density often coincide with tectonic plate boundaries where seismic activity is more frequent. Cities like Los Angeles and Mexico City are at significant risk due to their locations on active plates while also having large populations.
What does the cumulative death graph from earthquakes since 5000 BC indicate?
The graph shows a strong correlation between world population size and earthquake-related fatalities over time. As populations grow, particularly in urban areas, the potential for higher casualties during seismic events increases.
Discuss urbanization trends and their implications for disaster risk management.
Urbanization is projected to rise from 54% of the global population currently living in urban centers to approximately 68% by 2050. This trend raises concerns about megacities’ vulnerability; a high-magnitude earthquake could potentially result in catastrophic casualties if it strikes densely populated areas.
How do megacities relate to earthquake fatalities?
Regions with high populations tend to experience more earthquake-related fatalities. For instance, China has many supercities and has recorded around 290,000 deaths due to earthquakes.
What factors contribute to increased death risks during earthquakes?
Rapid urban growth leads to increased vulnerability as millions reside in inadequate housing made from poor materials situated in dangerous locations. By 2050, nearly half of the projected urban population may live under such conditions.
What anomalies are observed in the trends of natural disasters and droughts from 1970 to 2023?
An anomaly in the data shows that while the overall trend indicates an increase in natural disasters, the number of droughts significantly decreased in 2023 compared to previous years. This contrasts with the general upward trend observed from 1970 to 1980, followed by fluctuations until a notable decline in recent years.
How have deaths from natural disasters changed since the early 1900s?
The graph indicates a rapid decrease in deaths from natural disasters since the 1900s. In earlier decades, droughts and floods were the primary causes of mass fatalities. However, as time progressed, earthquakes emerged as the leading cause of death, despite not showing a consistent pattern of increase.
What significant changes occurred in the causes of death from natural disasters between the 1900s and recent decades?
In the early 1900s, droughts were the leading cause of death from natural disasters. By the mid-20th century, earthquakes became the primary hazard responsible for fatalities, while other hazards caused fewer deaths overall.
What is the projected population living in urban areas by 2050, and what implications does this have for disaster risk?
By 2050, it is projected that approximately 68% of the global population will reside in urban areas, equating to around 6.6 billion people. This urbanization trend raises concerns about increased vulnerability to natural disasters, particularly if high-magnitude earthquakes strike densely populated megacities.
What correlation exists between population density and earthquake fatalities?
The correlation between population density and earthquake fatalities is evident; regions with higher populations tend to experience more deaths during seismic events. This is particularly pronounced in countries with many supercities that are also prone to seismic activity.
What is Istanbul’s earthquake risk based on its geographical location?
Istanbul sits on the North Anatolian Fault, known for its rapid movement and regular sequence of earthquakes. Seismologists estimate a 35%-70% probability of a magnitude greater than 7 occurring near Istanbul within the next 30 years due to its geological setting.
What factors influence whether cities like Istanbul will experience a future megadisaster?
The likelihood of a megadisaster in cities like Istanbul depends on several factors, including the probability of high-magnitude earthquakes hitting the city, governance quality, and dynamic pressures faced by urban populations.
What role does government transparency play in mitigating disaster risks?
Government transparency is crucial for effective disaster risk management. It facilitates the implementation of urban planning laws, building regulations, and seismic design standards that can significantly reduce vulnerability to geophysical hazards.
How does education contribute to building resilience against geophysical hazards?
Education regarding disaster causes and preparedness enhances community resilience. Training drills and educational campaigns help individuals understand risks and appropriate responses during emergencies.
What are some strategies for building resilience against geophysical hazards?
Strategies include education on disaster causes, improved building design, tsunami sea walls, land-use zoning, preparedness measures like emergency plans, insurance options, and technology integration for tracking during emergencies.
What challenges do governments face when relocating populations at risk from geophysical hazards?
Relocating large populations poses significant challenges due to logistical issues, financial constraints, and social dynamics. For example, relocating over 56,000 residents in Mocoa presents difficulties compared to smaller communities like Guinsaugon with only 1,500 residents.
