Tectonics
What is a volcano?
A volcano is an opening in the Earth's crust where hot magma, ahs and gases escape from below the surface
What is the focus/hypocenter?
the point within the earth where an earthquake rupture starts
What causes earthquakes?
- the earth is divided into a solid core, molten magma mantle and the crush, floating on top - the crust is broken into plates - convection currents in the magma cause the plates to move in different directions - most earthquakes occur at the plate boundaries
What is magnitude?
a numerical expression of the amount of energy released by an earthquake
The process of convection currents
1) Magma (semi-molten rock) near the outer core is heated 2) As the magma warms it expands and becomes less dense 3) The less dense magma then starts to rise towards the crust 4) As the magma nears the crust it begins to cool 5) The cooling magma becomes denser and being to sink 6) The rising and falling magma creates circular currents with the mantle 7) It is these currents that create friction with the crust above and causes it to move
What are the features of a volcano?
1. Magma chamber 2. Bedrock 3. Pipe/ conduit 4. Base 5. Sill 6. branch pipe 7. Layers of ash 8. Flank (sides) 9. Layers of lava 10. Throat 11. Parasitic cone 12. Lava flow 13. Crater 14. Vent 15. Ash cloud
What is a hotspot volcano?
A hotspot occurs when there is intense heat in the mantel which rises towards the crust When the melted rock magma reaches the surface it creates volcanoes eg: the Hawaiian island
How do you prepare for an earthquake?
California preparation Have emergency equipment in your house, like: - A fire distinguisher - A first aid kit - Have enough water for each person for minimum three days - Get earthquake insurance - Have a relative that you can call who lives out of town to let them know that you care okay - Bolt your house - Know where to go in the event of an earthquake Japan preparation - Do an earthquake drill once a year - Has a switch to turn of the bullet train if an earthquake was to occur -> less rick of crash - Earthquake preparation is part of the Japanese curriculum. General preparation - Constructing building and roads that withstand earthquakes. E.g. Taipei 101, The Burj Khalifa Training emergency services and having them available, e.g. helicopters, ambulances and fire engines. Organising emergency services to provide water, food and power. Setting up a warning and information system for use of TV and radio.
What are the four types of plate boundaries?
Destructive/ convergent Constructive / divergent Collision/ convergent Conservative/ transform
What were the economic effects of the Haiti earthquake?
Economic impacts of the earthquake (effects on money and jobs) 30,000 commercial buildings collapsed. Businesses destroyed. Damage to the main clothing industry. Airport and port damaged. 250,000 homes 60% of government buildings, were either destroyed or badly damaged. Transport and communication links were also badly damaged by the earthquake. The main prison was destroyed and 4,000 inmates escaped. 1 in 5 people lost their jobs because so many buildings were destroyed. Haiti's largest industry, clothing was one of the worst affected
What are the opportunities that living near or on a volcano offer?
Fertile soil Some types of lava and ash weather rapidly in tropical conditions and form rich soils which are fertile. Which means crops grow in a shorter amount of time. EXAMPLE: Java, Indonesia Tourism Volcanoes attract many tourists due to - Warm bathing lakes - Hot springs - Bubbling mud pools and steam vents - Skiing in the winter Tourism creates jobs in shops, restaurants, hotels and tourist centres / national parks. Locals economies can profit from volcanism Provides huge waterfalls, wildlife, climbing and hiking EXAMPLE: Iceland Geothermal energy Geothermal energy is where heat from within the Earth is used to generate electricity. Geothermal energy can be generated in areas where magma lies close to the surface. This is good for increasing our renewable energy use. EXAMPLE: Mount Ijen, Java Minerals and mining Magma rising from deep inside the earth contains a range on minerals. As the rock cools, minerals are precipitated out. In some extinct volcanoes you can mine copper, gold, silver, lead, tin, zinc and even diamond. In some active or dormant volcanoes hot gases like sulphur escape through the vents and then solidifie - locals collect sulphur and sell it. New land When volcanoes are created or erupt new land is created which could be used for crowing crops or more buildings (infrastructure)
Shield Volcano - shape, appearance and eruption characteristics
Gentle sloping slides, layers of just lava, no parasitic cones. there is runny lava that covers w die area. Gases escape very easily from shield volcanoes. With shorter time between eruptions, but not very violent reaction.
How and why do the shape and nature of volcanic eruptions differ?
If a volcano produces very fluid lava (low in the compound SiO2, or silica), the magma flows a long distance before it cools, making a flat, shield-shaped volcano. If the volcano produces very sticky magma (high in silica) it tends to have an explosive eruptive style that includes lava, pyroclastic flows, and ash. this will make stravo volcano
What is the structure of the earth?
Inner core - Extremely hot, solid sphere made up of mostly iron and nickel Outer core - Liquid layer, made up of mostly iron and nickel Mantle - Properties of a solid, but can flow very slowly (semi-molten rock) It is split up into two regions upper and lower (The mantle is hotter towards the core and cooler towards the Earth's surface) Asthenosphere - Semi-liquid layer, the upper layer of the earth's mantle, directly below the lithosphere Lithosphere - Made up of the crust and a tiny bit of the upper mantle. This layer is divided up into several constantly moving plates of solid rock Crust - Hard and rigid, earths outermost and thinnest layer
How do you predict an earthquake?
It is harder to predict the time and location of an earthquake than a volcanic eruption. However it is possible to: Install sensitive instruments that can measure an increase in earth tremors (seismometres), pressure, and any release of radon gas. Map epicentres and frequencies of previous earthquakes to see if there is a location and/or time pattern (this can only give possible timings of an event and not a precise location). Observe unnatural animal behaviour - dogs howling, fish jumping, mice fleeing houses (less scientific but has proven useful).
What happens at a constructive plate boundary?
It is when any (same type) two plates move away from each other. Magma (molten rock) from the mantle rises up and fills the gap. It either cools and solidifies to form new land or rises up as lava in a volcano. This process underwater is called sea floor spreading and on land it is called rifting. EXAMPLE - The North American plate and Eurasian plate are moving apart at the mid-Atlantic Ridge
What issues and problems do LEDCs face when planning / preparing for the risk of earthquakes?
Lack of money (to build earthquake resistant structure, earthquake eqipment) Lack of emergency services Lack of knowledge and education about earthquakes
What were the long responses of the Mount Merapi eruption?
Long term 2,682 people were moved to new, safer houses permanently. The government made money available to farmers to help replace their livestock. The government set up a special task force to support people who were affected by the volcano, either by family issues, or because they lost their jobs. An ongoing exclusion zone of 2.5 km was set up settling people in areas of lower risk. Improved prediction measures and education in evacuation procedures have been introduced. Dams have been built in valleys to hold back lahars.
What were the long term responses to the Haiti earthquake?
Long term Water and sanitation eventually supplied for 1.7 million people. Temporary schools created and new teachers trainee. Support for people without jobs, which equates to nearly 70% of the population, through cash/food-for-work projects. 1 million people still without houses after 1 year so still have to live in aid camps. 98% of the rubble on the roads hadn't been cleared restricting aid access. 50% of the population lived below the poverty line, after the earthquake that increased to 80%. Future planning Prepared people on what to do during an earthquake. Trained emergency services. Practice evacuations. Training home owners and builders how to make homes more earthquake ready. Land use zoning - deciding whether the land is worth building on because it might get destroyed by a earthquake.
What were the primary or immediate effects of the Haiti earthquake?
Many of the effects were immediate or primary, eg injuries from falling buildings. Some secondary effects didn't happen until many months later, eg cholera outbreaks(9 months after cholera spread). The effects of this earthquake were particularly bad because of the following reasons: There were very few earthquake-resistant buildings Buildings and other structures were poorly built Settlements were built on steep slopes - bad foundation The epicentre was near to the capital There were few resources to rescue or treat injured people
What is the difference between oceanic and continental crust?
Oceanic crust characteristics: Location - ocean floor Thickness - thin (5-7km thick) Rock type - basalt Density - very dense Age - newer Can be renewed or destroyed Continental crust characteristics: Location - Areas of shallow seabed close to their shores Thickness - thick (35-40km thick in some places 55-60km) Rock type - granite Density - less dense (floats on top of the earths mantle Age - older Cannot be renewed or destroyed
Where are volcanoes located?
Pacific Ring of Fire Mid Atlantic Ridge East of Africa, riff valley Southern Europe
What were the positive and negative impacts of the Mount Merapi eruption?
Positive Ash will eventually lead to more fertile soils in the area. New data from the eruption has enabled hazard mapping to be updated and used to set up exclusion zones around the volcano. Negative 353 people were killed and 577 people were injured. Overcrowded evacuation centres led to poor sanitation, no privacy and a serious risk of disease. People, particularly farmers, lost their homes and livelihoods. 350,000 people were made homeless.
What were the primary short term effects of the Mount Merapi eruption?
Primary Volcanic bombs and heat clouds, with temperatures up to 800°C, spread over a distance of 10 km. Pyroclastic flows travelled 3 km down the heavily populated mountain sides. Volcanic ash fell up to 30 km away and travelled 6 km into the sky. Villages, such as Bronggang, 15 km from the volcano, were buried under 30 cm of ash. Sulphur dioxide was blown across Indonesia, the Indian Ocean and as far south as Australia. Pyroclastic flows, at speeds of up to 100 km/h were recorded.
What are the hazards that volcano eruptions present to humans?
Primary hazards: Pyroclastic flows - Kill/crush/injure/burn people Volcanic bombs - Destroy/damage/burn buildings Lava flows - Disruption to transport Structural Collapse: Debris flow-Avalanches Volcanic gas - Poison from toxic gas/suffocate/breathing difficulties/choke people Mass movement (avalanches) - crush/kill people, destroy buildings General - Reduced visibility Secondary hazards: Lahars - Drown/crush people, damage buildings Ash cloud - Destroy/damage/burn farmland Climate change Tsunami Acid rain
What were the secondary short term effects of the Mount Merapi eruption?
Secondary The ash plumes from the volcano caused major disruption to aircraft flying over Indonesia. Roads were blocked with cars and motorcycles as residents tried to flee the hazard zone. Vegetable prices increased because of the damage to crops. 350,000 people living in the area had to flee their homes. Heavy rain on 4th November caused lahars, washing ash and rock down into towns and destroying bridges.
What are the methods of monitoring a volcano to lessen the impact of an eruption?
Seismology Seismometers - used to measure earthquakes occurring near an eruption When magma rises rocks break and seismometers detect this. This will tell us that a volcano is about to erupt. Gases As magma moves up the volcano gases like carbon dioxide and sulphur dioxide start to be emitted. The amount of gas tells us how near the volcano is to erupting. Other 'signs' Small plumes of gas form from the top of the volcano. Tilt metres and GPS satellites - these devices monitor any changes in landscape. Volcanoes tend to swell near an eruption. Measuring temperature - volcanoes become hotter when magma starts to rise through the main vent. Looking at the past history of eruptions - scientists can identify patterns of activity. Issues of prediction If the predictions are inaccurate people will be told to evacuate and the have to return home because they were false alarms. If this happens a lot people might stop listening and not evacuate so they might get hurt.
What were the short responses to the Haiti earthquake?
Short term $100 million in aid given by the USA and $330 million by the European Union. 4.3 million people provided with food rations in the weeks following the earthquake. Lack of immediate aid through poor planning, management and access meant that people had to try and rescue each other. Healthcare supplies provided to limit disease. 115,000 tents and 1,000,000+ tarpaulin shelters provided. 810,000 people placed in aid camps. Members of social networking sites such as Twitter and Facebook, spread messages and pleas to send help. The USA sent ships, helicopters, 10,000 troops.
What were the short responses of the Mount Merapi eruption?
Short term 210 evacuation centres were set up in schools, churches, stadiums and government offices. An exclusion zone of 20 km was established around the volcano. Indonesian Disaster Management Agency mobilized volunteers, the military and police to circulate information, rescue survivors, control traffic, set up makeshift hospitals and kitchens in evacuation centres. International aid was offered from governments and non-governmental organisations (NGOS) such as the Red Cross and Red Crescent. Over 350,000 people were evacuated from the affected areas. An initial 10 km evacuation zone was established. Schools were closed up to 120 km west of the volcano. Jobs have been provided in the tourism industry. The Australian government pledged almost $1 million in aid.
What were the social effects of the Haiti earthquake?
Social impacts of the earthquake (effects on people) 3 million people affected. Over 220,000 deaths. 300,000 injured. 1.3 million made homeless. Several hospitals collapsed. Hospitals (50+) and schools (1,300+) were badly damaged, as was the airport's control tower. Over 2 million people were left without food or water.
Stratovolcano - shape, appearance and eruption characteristics
Stratovolcano: Steep-sided and cone-shaped, made up of layers of ash and lava and containing acidic sticky lava which doesn't flow very far because it solidifies. Longer times between eruptions. Steep slopes, narrow base, cone shape Violent explosions Creates large ash clouds Acid lava Lower temperatures - 800 degrees C High about of gas trapped High viscosity High silica Formed when oceanic crust is subducted
What are plate tectonics?
Tectonic plates are pieces of the rocky outer layer of the Earth known as the crust. These plates are constantly moving, and volcanoes and earthquakes are found at plate boundaries
What is the difference between a Richter scale and a Modified Mercalli scale?
The Mercalli scale describes the intensity of an earthquake based on its observed effects The Richter scale describes the earthquake's magnitude by measuring the seismic waves that cause the earthquake.
Why is the earth restless
The earth is always moving, continually influenced by the: Sun Gravity Complex interactions with oceans and atmosphere Vibrations of the seismic waves Surface change- deformation Sea level
What are convection currents?
The plates are moving because of convection currents in the mantle underneath the crust Yet more of the Earth beneath us isn't solid, it is made out of semi-liquid molten rock that cycles and flows through convection currents in the mantle The inner core heats the liquid then cooling down, and the cycle repeats called a convection current
What is a plate boundary?
The region where two or more tectonic plates meet. It is a zone of intense seismic waves
What does the effect of an earthquake depend on?
The size of the earthquake on the Richter scale - the higher it is on the scale, the more destruction it can cause. Level of development - whether it occurs in a rich or a poor country. Richer countries will be more likely to be able to predict, protect and prepare themselves from the effects of an earthquake. The depth of the focus - if it's shallow, it can be more destructive. Distance from epicentre - the effects of an earthquake are more severe at its epicentre and if a town/city is near it, it could get badly damaged. Population density - the more people living in an area, the more likely that more deaths and casualties may arise. The time of day - if an earthquake happens during the night people will respond slower (slower reaction time). However if it happens during the day they will react quicker. The geology of the rock - harder rock absorbs more of the energy causing less damage because there is less force. However soft rock doesn't absorb as much energy and might also move (wiggle) a lot more causing destruction. Building structure - if buildings are made to withstand earthquakes they are less likely to get collapse therefore less people are likely to get killed.
What is the global distribution of earthquakes?
Uneven On/near plate boundaries/where plates meet/edge of a plate boundary Eg. Pacific Ring of Fire They occur along all types of plate margins specifically: On destructive plate margins - where plates are moving towards each other On conservative plate margins - where the plates are sliding past each other
What is the global distribution of volcanoes?
Uneven On/near plate boundaries/where plates meet/edge of a plate boundary like Mount Saint Helen's On destructive plate margins - where plates are moving towards each other Eg. Pacific Ring of Fire On constructive plate margins - where the plates are moving apart However there are some exceptions like Mauna Loa which lie on hotspots
What happens at a destructive plate boundary?
When an oceanic and continental plate are moving towards each other the denser oceanic plate is forced under the less dense continental plate. This process is called subduction. Due to the huge amounts of friction the oceanic plate melts in the mantle. This creates pressure to build up in the mantle until there is so much that magma is forced through weaknesses and cracks causing a volcano eruption. EXAMPLE - The Nazca plate is being forced under the South American plate
What happens at a collision plate boundary?
When two continental plates are colliding, neither sink (or are subducted) below the other because they have the same densities. Instead they both crumple upwards creating fold mountains. EXAMPLE - The Eurasian and the Indian plates are colliding creating the Himalayas
What happens at a conservative plate boundary?
When two plate are moving in the same direction at different speeds or in opposite directions they can get stuck due to the rough texture. This causes friction to build up. The friction is eventually overcome and the plates slip past each other in a sudden movement. The shock waves can create earthquakes. EXAMPLE - The pacific plate is moving past the North American plate on the West coast of the USA, e.g. at San Andreas fault.
What are the causes of an earthquake?
When two plates are colliding/ trying to move past each other they can get stuck and locked together, due to the friction between them. Kinetic energy builds up causing pressure. Overtime the pressure builds up and becomes too great causing the stored kinetic energy to suddenly be released. Seismic waves radiate outwards from the focus in all directions. Seismic waves are strongest at the epicentre which is the point on the earth's surface directly above the focus. Aftershocks occur as the plates settle into their new position.
What were the causes of the Mount Merapi eruption?
Where? South East Asia in the country of Indonesia. It is North of Yogyakarta and West of Solo on the island of Java, (central Java). When? Monday, 25 October Three major eruptions were recorded at 14:04, 14:24 and 15:15 local time (afternoon). Why? The volcano and its eruptions were caused by the Indo-Australian Plate being subducted beneath the Eurasian Plate. (located on a destructive plate margin). Mount Merapi is part of the Pacific Ring of Fire. What? Mt Merapi (meaning the mountain of fire) is an active strato volcano (composite)
What were the causes of the Haiti earthquake?
Where? The earthquake's epicentre was 25 km west of Port-au-Prince, the capital. Most people, businesses and services were located in the capital. When? It occurred January 12, 2010 and hit at 4.53pm Why? - Haiti is sitting on 2 plate boundaries - The earthquake was caused by the North American Plate sliding past the Caribbean Plate at a conservative plate margin - Both plates move in the same direction, but one moves faster than the other What? A 7.0 magnitude Earthquake hit Haiti, being the fifth-deadliest earthquake in history Magnitude was 7.0 soon followed by two aftershocks of magnitudes 5.9 and 5.5. By the 24th January 52 aftershocks had been recorded all measuring 4.5 or more. Focus was at a depth of 13 km (8.1 mi). One of the world's poorest countries - 1/3 Haitians live on less than $2 a day and over half on less than $1. Only 25 doctors and 11 nurses per 100,000 of the population - most of these in urban areas. Only 46% of people had access to clean water. Nearly 40% of children do not attend school. Fewer than 20% of Haitians aged 15 or over are literate.
What is a fault?
a break in the earth along which movement occurs
What is after shock?
an earthquake of similar or less intensity that follows the main earthquake
what is a seiometre?
an instrument that can record the ground motion from an earthquake
What is the Modified Mercalli Scale?
an intensity scale that consists of a series of certain key response such as people awakening, movement of furniture, damage to chimneys and finally total destruction
What plate boundaries do volcanoes occur on?
constructive: calmer explosions destructive: dangerous explosions
what is a epicentre?
location on the surface of the earth directly above the focus
what scale measures earthquake?
richter scale, measuring the amount of energy released in a earthquake
What is a seismic wave?
the vibrations from earthquake that travel through the earth
