1B Hazardous Earth Flashcards
What are the 4 layers of earth
Inner core
Outer core
Mantle
Crust
What are convection currents?
Convection currents are heat-driven cycles that occur in the air, ocean, and mantle. They are caused by a difference in temperature, often due to a differing proximity to a heat source. The difference in temperature relates directly to the density of the material, causing this effect.
Name 5 plates
North American plate
Eurasian plate
African Plate
Indo-Australian plate
Philippines plate
Pacific plate
Antarctic plate
Caribbean plate
Arabian plate
Nazca plate
3 different types of plate boundaries, examples of them, features produced and examples of plates
Convergent:
Move towards each other, happens when an oceanic plate meets a continental plate, the denser oceanic plate sinks under the less dense continental plate. Leads to the formation of a deep trench where two plates meet. The huge increase in pressure and temperature force it to release water and other impurities into the asthenosphere, which begins to melt. Magma then rises and breaks through the earths surface as an opposite volcano.
Divergent:
Plates move apart. Mostly happens under oceans. As the plates break apart, rise in heat and a eduction in pressure causes the asthenosphere to melt, forming magma which then rises to fill the gap. When the magma breaks through earths surface, it forms a shield volcano, as this process continues, a row of volcanos are formed to form a mid ocean ridge. Earthquakes can also occur at divergent plate boundaries.
As the plates do not always move apart smoothly. However the earthquakes tend to not be large
Conservative:
Plates slide past each other. In Haiti the North American plate boundary and the Caribbean plate are moving in opposite directions. At the San Andreas fault in California, however, the North American plate and pacific plate are moving in similar direction, at slightly different angles and speeds. In both examples, the plates tend to get stuck at some point. Pressure builds up along the boundary until one plate jerks past another causing earthquake
Compare composite volcanoes to shield volcanoes
Comparison of Shield Volcanoes and Composite Volcanoes
• Shape
• Shield Volcanoes: Broad with gentle slopes, resembling a warrior’s shield.
• Composite Volcanoes: Steep, conical shape with a stratified profile.
• Size
• Shield Volcanoes: Much wider than they are tall, often covering large areas.
• Composite Volcanoes: Taller relative to their base but with a narrower footprint.
• Magma Composition
• Shield Volcanoes: Basaltic magma with low silica content, low viscosity, flows easily.
• Composite Volcanoes: Andesitic to rhyolitic magma with high silica content, high viscosity, flows slowly.
• Eruption Style
• Shield Volcanoes: Non-explosive and effusive, with free-flowing lava.
• Composite Volcanoes: Highly explosive, producing ash, pyroclastic flows, and lava bombs.
• Hazards
• Shield Volcanoes: Generally less dangerous; lava flows can destroy property over large areas.
• Composite Volcanoes: Extremely hazardous, with potential for widespread destruction and loss of life.
• Formation
• Shield Volcanoes: Built from successive layers of lava that flow outward.
• Composite Volcanoes: Built from alternating layers of lava, ash, and tephra.
• Plate Boundary Formation
• Shield Volcanoes:
• Hotspots: Magma rises through the lithosphere (e.g., Hawaiian Islands).
• Divergent Boundaries: Plates pull apart, allowing magma to surface (e.g., Mid-Atlantic Ridge).
• Composite Volcanoes:
• Convergent Boundaries (Subduction Zones): One plate is forced under another, causing magma to rise (e.g., Mount St. Helens, Mount Fuji).
• Examples
• Shield Volcanoes: Mauna Loa (Hawaii), Kilauea (Hawaii), Galápagos Islands.
• Composite Volcanoes: Mount St. Helens (USA), Mount Fuji (Japan), Mount Vesuvius (Italy).
What are hotspots
Volcanoes which are formed away from plate boundaries, they are formed by a plume of superheated rock rising very slowly through the mantle.
Primary and secondary impacts of volcanic hazards
Primary: injury, loss of life, destruction of property, disruption to communications.
Secondary: shortages of water and food, spread of disease, social and economic problems
Emergency and long-term responses to volcanic hazards
Emergency: rescuing people, providing medical aid, food and water and restoring water and electricity.
Long term: restoring area back to normal, managing future hazards,
What happened in the Kilauea eruptions? (primary, secondary impacts and emergency and long term responses)
Kīlauea, located on Hawaiʻi’s Big Island, is among the world’s most active volcanoes. Its eruptions have had significant primary and secondary impacts, prompting both immediate emergency responses and long-term recovery efforts.
Primary Impacts:
• Lava Flows: The 2018 lower East Rift Zone eruption inundated approximately 14 square miles (35.5 square km) of land, destroying 1,839 structures and damaging 90 more. 
• Geographical Changes: The eruption led to the collapse of Kīlauea’s summit caldera and the draining of the Halemaʻumaʻu lava lake. 
Secondary Impacts:
• Air Quality Issues: Elevated levels of sulfur dioxide gas were released during eruptions, leading to the formation of volcanic smog (vog), which poses health risks to residents and visitors. 
• Environmental Damage: Lava flows destroyed Hawaii’s largest natural freshwater lake and covered substantial portions of residential areas, leading to loss of habitats and agricultural land. 
Emergency Responses:
• Evacuations: Residents in affected areas, such as Leilani Estates and Kapoho, were evacuated to ensure their safety. 
• Monitoring and Alerts: The Hawaiian Volcano Observatory issued regular updates and warnings to keep the public informed about volcanic activity. 
Long-Term Responses:
• Infrastructure Rehabilitation: Efforts were made to rebuild and repair infrastructure damaged or destroyed by lava flows, including roads and utilities.
• Community Support: Programs were implemented to assist displaced residents with housing and financial aid.
• Environmental Restoration: Initiatives aimed to rehabilitate ecosystems affected by the eruptions, focusing on reforestation and habitat restoration.
The 2018 Kīlauea eruption serves as a reminder of the dynamic nature of volcanic activity and the importance of preparedness and resilience in affected communities.
What happened in the pinatubo eruption? (primary, secondary impacts and emergency and long term responses)
The 1991 eruption of Mount Pinatubo in the Philippines was one of the largest volcanic eruptions of the 20th century. Here’s an overview of the event, its primary and secondary impacts, and the responses:
Primary Impacts
1. Volcanic Eruption:
• The eruption on June 15, 1991, produced a massive ash plume that reached 35 km into the atmosphere.
• The release of 10 cubic kilometers of volcanic material included ash, pumice, and pyroclastic flows.
• Over 847 people died, mainly from roofs collapsing under the weight of ash mixed with rain from Typhoon Yunya.
2. Ash and Gas Emissions:
• Sulfur dioxide emissions were approximately 20 million tons, causing a global cooling effect.
• Large-scale destruction of vegetation and farmland due to ashfall.
3. Lava Flows and Pyroclastic Flows:
• Pyroclastic flows devastated areas within 16 km of the volcano, destroying infrastructure and homes.
4. Displacement of People:
• Over 200,000 people were displaced as entire communities were buried under ash and lahars.
Secondary Impacts
1. Lahars:
• Heavy rains triggered massive lahars (mudflows of volcanic debris), which destroyed villages, infrastructure, and agricultural land for years after the eruption.
2. Climate Effects:
• The eruption caused global temperatures to drop by 0.5°C for about 2-3 years due to the sulfur dioxide forming reflective sulfate aerosols in the stratosphere.
3. Economic Damage:
• Estimated losses reached $700 million to $1 billion.
• Agriculture and industry were severely affected, with 800 km² of farmland rendered unusable.
4. Health Problems:
• Respiratory issues from ash inhalation and increased incidences of waterborne diseases in evacuation centers.
5. Environmental Damage:
• Local ecosystems were disrupted, with rivers and forests buried under volcanic material.
Emergency Responses
1. Evacuations:
• Approximately 58,000 people were evacuated before the eruption, largely due to the efforts of the Philippine Institute of Volcanology and Seismology (PHIVOLCS) and the U.S. Geological Survey (USGS).
2. Shelter and Aid:
• Emergency shelters were set up for displaced residents.
• Relief operations provided food, water, and medical aid to affected communities.
3. Monitoring and Alerts:
• Continuous monitoring and hazard assessments by PHIVOLCS and USGS minimized casualties.
Long-Term Responses
1. Resettlement Programs:
• Communities in high-risk areas were permanently relocated to safer zones.
• The government provided housing and livelihood assistance for displaced families.
2. Lahar Control Projects:
• Dams, dikes, and drainage systems were built to manage lahars and reduce future risks.
3. Rehabilitation of Agriculture and Infrastructure:
• Efforts were made to restore agricultural productivity by clearing ash-covered fields and improving irrigation systems.
4. Improved Disaster Preparedness:
• Lessons from Pinatubo led to better volcanic hazard monitoring and disaster response systems in the Philippines.
5. Environmental Recovery:
• Reforestation and rehabilitation programs were initiated to restore ecosystems.
The eruption of Mount Pinatubo was devastating but demonstrated the importance of scientific monitoring and coordinated disaster management in reducing casualties and aiding recovery.
Why do most earthquakes occur at convergent plate boundaries?
Most earthquakes occur at convergent plate boundaries because of the intense stresses generated when two tectonic plates collide. The mechanisms at these boundaries create conditions that lead to frequent and powerful seismic activity. Here’s why:
- Plate Movements and Stress Accumulation
• At convergent boundaries, two plates move toward each other, and the interaction creates immense pressure and deformation.
• There are three main types of convergence, each associated with earthquakes:
• Oceanic-Continental Convergence: The denser oceanic plate subducts beneath the less dense continental plate, forming a subduction zone.
• Oceanic-Oceanic Convergence: One oceanic plate subducts beneath another, creating deep trenches and volcanic island arcs.
• Continental-Continental Convergence: Two continental plates collide, causing the crust to buckle and fold, forming mountain ranges.
The forces in all these scenarios build up stress along faults, which is eventually released as earthquakes.
- Subduction Zones
• Subduction zones are particularly earthquake-prone:
• As the subducting plate descends into the mantle, it bends, cracks, and scrapes against the overriding plate, generating stress.
• Friction between the plates causes energy to accumulate until it is released in sudden seismic activity.
• Earthquakes occur at varying depths along the Wadati-Benioff zone, a sloping plane of seismic activity that follows the subducting plate. - Faulting and Friction
• Convergent boundaries are associated with several types of faults:
• Thrust Faults: Large sections of the crust are forced upward or downward, leading to powerful earthquakes.
• The compressional forces at these boundaries create some of the largest earthquakes on Earth, such as the 2011 Tōhoku earthquake in Japan. - Pressure and Rock Deformation
• At convergent boundaries, the compressional forces deform rocks, which can lead to:
• Folding and fracturing of the crust.
• The sudden release of energy along faults when the strength of the rocks is exceeded. - Depth and Magnitude of Earthquakes
• Convergent boundaries produce earthquakes at various depths:
• Shallow earthquakes (<70 km depth): Occur near the surface where plates initially collide.
• Intermediate and deep earthquakes (70–700 km depth): Occur in subduction zones as the plate descends into the mantle.
• Earthquakes at convergent boundaries are often high in magnitude because of the immense energy released from the movement of large sections of the Earth’s crust.
Examples of Earthquake Activity at Convergent Boundaries
• Pacific Ring of Fire: Subduction of oceanic plates beneath continental and other oceanic plates causes frequent and powerful earthquakes.
• Himalayas: The collision of the Indian and Eurasian plates produces shallow but intense earthquakes.
• Andes Mountains: Subduction of the Nazca Plate beneath the South American Plate causes significant seismic activity.
In summary, most earthquakes occur at convergent boundaries because of the intense compressional forces, friction, and deformation generated by the collision and subduction of tectonic plates. These processes create the conditions for frequent and often powerful seismic events.
What scale is used to measure magnitude of earthquakes? And what does it do
Richter scale, it gives a value between 1 and 10. An earthquake 7 on the scale is 10 times more powerful than the one measured at 6 and 100 times more powerful than the one at 5.
How is the size of a wave measured?
With a seismometer
What are tsunamis?
A series of giant ocean waves that send surges of water, sometimes over 30m high, onto land.
Impacts and responses to the tohoku earthquakes
The 2011 Tōhoku earthquake (magnitude 9.0) struck off the northeastern coast of Japan on March 11, 2011. It was one of the most devastating natural disasters in history, triggering a massive tsunami and causing widespread destruction. Below is a breakdown of its impacts and responses:
Impacts of the Tōhoku Earthquake
Primary Impacts
1. Ground Shaking:
• The earthquake lasted around 6 minutes and caused severe ground shaking across northeastern Japan.
• Buildings, bridges, and roads were destroyed, especially in areas close to the epicenter.
2. Tsunami:
• A massive tsunami, with waves reaching up to 40 meters, inundated coastal regions.
• Entire towns, such as Rikuzentakata and Minamisanriku, were wiped out.
• Over 15,800 people were killed, primarily due to drowning.
3. Fukushima Nuclear Disaster:
• The tsunami damaged the Fukushima Daiichi Nuclear Power Plant, leading to a Level 7 nuclear meltdown.
• Radiation leaks forced over 150,000 people to evacuate the surrounding area.
4. Infrastructure Damage:
• Roads, railways, ports, and airports were severely damaged.
• Power outages affected 4.4 million households, and water supplies were disrupted for 1.5 million homes.
Secondary Impacts
1. Economic Damage:
• Estimated economic losses were around $360 billion, making it the costliest natural disaster ever recorded.
• Industries such as fishing, manufacturing, and agriculture were severely affected.
2. Displacement and Homelessness:
• Over 450,000 people were displaced and housed in temporary shelters.
• Thousands of homes were destroyed by the tsunami and earthquake.
3. Environmental Impacts:
• The tsunami deposited debris and toxic materials along the coastline.
• The nuclear meltdown contaminated land and water, causing long-term environmental challenges.
4. Global Ripple Effects:
• The nuclear disaster led to a decline in nuclear energy use worldwide.
• Disruptions in Japan’s industrial output, especially in the automotive and electronics sectors, affected global supply chains.
Responses to the Tōhoku Earthquake
Immediate/Emergency Responses
1. Search and Rescue:
• Around 100,000 personnel, including Japan’s Self-Defense Forces, were deployed for rescue and relief operations.
• International assistance came from over 20 countries, including the U.S., South Korea, and Australia.
2. Evacuations:
• Immediate evacuation orders were issued for areas near the Fukushima power plant.
• Coastal residents were evacuated to higher ground due to tsunami warnings.
3. Relief Efforts:
• Emergency shelters were established for displaced individuals.
• Food, water, medical supplies, and blankets were distributed by both the government and NGOs.
4. Tsunami Warning System:
• Japan’s advanced tsunami warning system issued alerts within minutes, helping save thousands of lives.
Long-Term Responses
1. Reconstruction Efforts:
• The Japanese government allocated over $250 billion for rebuilding infrastructure and communities.
• Entire towns were rebuilt with elevated platforms to avoid future tsunami damage.
2. Improved Disaster Preparedness:
• Strengthened building codes and tsunami defenses, such as higher sea walls and better evacuation routes.
• Enhanced early warning systems for both earthquakes and tsunamis.
3. Fukushima Cleanup:
• Efforts to decommission the Fukushima Daiichi plant and decontaminate the surrounding area are ongoing and expected to take decades.
• Compensation and relocation support were provided to those affected by radiation.
4. Economic Recovery:
• The government provided financial aid to businesses and communities to help recover economic stability.
• Global supply chains were restored over time, particularly in the automotive and electronics sectors.
5. Public Awareness and Education:
• Nationwide disaster drills and education programs were enhanced to ensure preparedness for future events.
Legacy
The Tōhoku earthquake highlighted the importance of disaster preparedness, response coordination, and resilient infrastructure. While Japan’s pre-existing systems saved many lives, the disaster underscored the challenges of mitigating secondary impacts such as nuclear accidents and economic disruptions. It remains a critical case study for understanding and managing catastrophic events.
How to reduce the impact of earthquakes
Trained emergency services
National prevention days where drilled on what to do in 5e event of an earthquake
New buildings are fitted with strict building codes which allow the building to move with the earthquake.
Impacts and responses to the Haiti earthquake
The 2010 Haiti earthquake, a magnitude 7.0 event, struck near Port-au-Prince, the capital of Haiti, on January 12, 2010. The disaster caused widespread devastation due to the country’s vulnerability and lack of preparedness. Below is an analysis of its impacts and responses:
Impacts of the Haiti Earthquake
Primary Impacts
1. Loss of Life and Injuries:
• Approximately 230,000 people were killed, and over 300,000 were injured.
• Thousands were trapped under collapsed buildings.
2. Widespread Destruction:
• Over 250,000 homes and 30,000 commercial buildings were destroyed or severely damaged.
• Key infrastructure, including the presidential palace, parliament, schools, and hospitals, collapsed.
3. Port-au-Prince Epicenter:
• The earthquake’s proximity to the densely populated capital resulted in catastrophic damage to urban areas.
4. Infrastructure Failure:
• Roads, bridges, and the main port were destroyed, hindering rescue and relief efforts.
Secondary Impacts
1. Displacement and Homelessness:
• Over 1.5 million people were left homeless and forced to live in temporary camps.
• Many lived in unsafe conditions, vulnerable to disease outbreaks.
2. Economic Losses:
• The estimated cost of damage was $8-14 billion, equivalent to 120% of Haiti’s GDP.
• Businesses, agriculture, and trade were severely disrupted.
3. Health Crisis:
• Hospitals were overwhelmed, and medical supplies were insufficient.
• A cholera outbreak began in October 2010, linked to contaminated water, killing over 10,000 people.
4. Environmental Impacts:
• Rubble and debris covered much of Port-au-Prince, creating a hazardous environment.
• Deforestation and soil instability worsened due to emergency shelter construction.
5. Social and Political Disruption:
• The government’s ability to respond was severely hampered, with many officials killed or injured.
• Law and order deteriorated, leading to increased crime in some areas.
Responses to the Haiti Earthquake
Immediate/Emergency Responses
1. Search and Rescue:
• Initial rescue efforts were hampered by blocked roads and collapsed infrastructure.
• International teams from the U.S., France, and other countries arrived to assist with search and rescue operations.
2. Humanitarian Aid:
• Aid organizations like the Red Cross, UN, and Doctors Without Borders provided food, water, and medical care.
• Over 20 countries pledged support, including the U.S., which deployed 13,000 troops and provided significant financial aid.
3. Temporary Shelters:
• Camps were set up for displaced people, though they often lacked proper sanitation and security.
4. Financial Assistance:
• The international community pledged billions in aid, including $13 billion over several years.
Long-Term Responses
1. Reconstruction Efforts:
• Slow progress was made in rebuilding homes, schools, and hospitals.
• A “Build Back Better” approach was promoted to improve the resilience of new structures.
2. International Aid Coordination:
• The United Nations and NGOs worked to coordinate rebuilding efforts, though coordination was often criticized as inefficient.
• Only a portion of pledged funds was delivered, leading to delays in reconstruction.
3. Infrastructure Improvements:
• New roads and buildings were designed to better withstand future earthquakes.
• Efforts were made to rebuild the port and improve transportation systems.
4. Health and Sanitation:
• Cholera treatment centers were established, and vaccination campaigns were conducted.
• Clean water and sanitation infrastructure were prioritized in rebuilding efforts.
5. Disaster Preparedness:
• Haiti and international partners worked to improve early warning systems and disaster response plans.
• Training programs were established for local responders.
Challenges in Responses
• Aid Delivery Delays: Limited infrastructure and communication failures hindered the timely distribution of aid.
• Government Weakness: Haiti’s government was poorly equipped to lead recovery efforts, relying heavily on international organizations.
• Corruption and Mismanagement: Misuse of funds and a lack of accountability slowed rebuilding efforts.
• Prolonged Displacement: Many displaced people remained in camps for years, living in poor conditions.
Legacy
The Haiti earthquake highlighted the importance of disaster preparedness, resilient infrastructure, and coordinated international responses. However, it also revealed significant challenges in aid distribution, corruption, and long-term recovery in vulnerable nations.
