Problems caused by Under population - Australia

2.1 Earthquakes and volcanoes

Describe the main types and features of volcanoes and earthquakes

Key Vocabulary

Volcano Hotspot Magma Lava Chamber Crater Shield Volcano Strato/Cone volcano Active volcano Dormant Volcano Extinct Volcano

Crust Earthquake Deep focus earthquake Shallow focus earthquake Subduction zone Epicentre Focus Richter scale Seismograph Mercalli scale Reservoir

Volcano:  An opening in the Earth’s crust through which hot molten magma (lava), molten rock and ash are erupted onto the land.

Hotspot: Areas of weakness in the middle of a plate. Ex: Hawaii

Magma: Molten materials inside the Earth’s interior

Lava: When molten magma is ejected at the earth’s surface through a volcano or a crack at the surface, it is called lava

Chamber: Reservoir of magma located deep inside the volcano

Crater: Depression at the top of a volcano following a volcanic eruption

Vent: The channel which allows magma within the volcano to reach the surface in a volcanic eruption.

Types of volcanoes based on the type of Lava

Shield volcanoes: Flat topped volcanoes formed with runny lava at constructive plate boundaries or hotspots.

Strato volcanoes: Cone shaped volcanoes formed in layers of ash and lava at destructive plate boundaries

    

Types of volcanoes based on the frequency of occurence

Active volcanoes: Volcanoes that erupted in recent times and could erupt again.Ex: Mt.Sinabung, Indonesia

Dormant volcanoes: Volcanoes that have not erupted for many centuries but may erupt again.Ex: Mt.Rainier, USA

Extinct volcanoes: Volcanoes that are not expected to erupt again. Ex: Mt.Kilimanjaro, Tanzania

Earthquakes: Sudden violent shaking of the earth’s surface. They occur after a build-up of pressure causes rocks and other materials to give way.

Focus: The place beneath the ground where the earthquake takes place

Epicentre: The point on the ground surface immediately above the focus.

Subduction: One plate bends and slides underneath another plate, curving down into mantle

Types of Earthquakes

Deep-focus earthquakes associated with subduction

Shallow-focus earthquakes  are located along conservative and constructive plate boundaries

Richter scale:  An instrument used to measure the magnitude (strength or force) of earthquakes measured on a seismograph.

Mercalli Scale: The scale that relates to the ground movement to things that we would notice happening around you. The Mercalli Scale assigns a number to quantify the effects of an earthquake.

           

Difference between Richter scale and Mercalli scale

Richter scale	Mercalli scale
Uses Seismometer to measure vibrations	Uses the experience of eye witnesses
It is logarithmic. This means an earthquake of 6.0 is 10 times greater than one of 5.0, and 100 times more than one of 4.0	Relates to ground movement to things that we would notice happening around us
A scale, ranging from 1 to 10, for indicating the intensity of an earthquake.	A measure of earthquake intensity with 12 divisions ranging from I (felt by very few) to XII (total destruction).
Developed in 1935	Developed in 1884 and 1906

Describe and explain the distribution of earthquakes and volcanoes

Key Vocabulary

Plates Plate tectonics Fold mountains Rift valleys Convection currents Core Mantle Crust Ring of Fire Faulting Folding

Collision Continental crust Oceanic crust Constructive/Divergent Destructive/Convergent Conservative Trench Mid ocean ridge Sea floor spreading Ridges Trenches

è The distribution of the world’s volcanoes and earthquakes is very uneven

è They are mostly along plate boundaries which are regions of tectonic activity

è Most of them occur in linear chains, along all types of plate boundaries

è Some earthquakes appear away from plate boundaries such as in the mid west of the USA.

è Some earthquakes are caused by human activity:

·         Nuclear testing

·         Building large dams

·         Drilling for oil/natural gas (fracking)

·         Coal mining

è Volcanoes notably occur at destructive(strato), constructive(shield) plate boundaries and hotspots

è Three-quarters of the world’s active volcanoes are located in the ‘Pacific Ring of Fire’, the are around the Pacific ocean.

Plates: Huge land mass divisions of earth’s crust.

7 major plates	Some minor plates
Pacific, Indo-Australian, Antarctic, North American, South American, African and Eurasian	Caribbean, Iranian, Nazca, Arabian, etc

Plate tectonics: A set of ideas that describe and explain the global distribution of earthquakes, volcanoes, fold mountains and rift valleys.

Convection currents: The currents of the molten rock rising towards the earth’s surface. This causes the continents to be dragged apart and cause them to collide.

The crust is a solid and is divided into two main types:

Continental crust	Oceanic crust
The depth varies from 10 km to 70 kms	The depth varies from 6kns to 10 kms
Mostly formed of granite	Mostly formed of basalt
Less dense (Not heavier than oceanic crust)	Denser than Continental crust
Will not undergo subduction	Mostly undergoes subduction because of its weight

Types of plate boundaries

Constructive/divergent boundary	Destructive/convergent boundary	Collision/convergent boundary	Conservative/Transform boundary
Two plates move apart from each other causing sea floor spreading	The oceanic crust moves towards the continental crust and sinks beneath it due to its greater density	Two continental crusts collide as neither can sink, they are folded up into fold mountains	Two plates slip sideways past each other but land is neither destroyed nor created
New oceanic crust is formed, creating mid oceanic ridges	Deep sea trenches, island arcs and fold mountains are formed
Volcanic activity is common	Volcanic activity is common
E.g. Mid-Atlantic Ridge( Europe is moving away from N.America)	E.g. Nazca plate sinks under S.American plate	E.g. Indian plate collided with the Eurasian plate to form Himalayas	E.g. San Andreas fault in California

Faulting - when tension and compression associated with plate movement is so great that blocks of rock fracture or break apart. - process can occur very rapidly.

Folding – when two tectonic plates are pushed towards each other, the collision results in rocks and debris being pushed up into rocky outcrops, hills, mountains and mountain ranges.

Ridge - A mid-ocean ridge or mid-oceanic ridge is an underwater mountain range, formed by plate tectonics. This uplifting of the ocean floor occurs when convection currents rise in the mantle beneath the oceanic crust and create magma where two tectonic plates meet at a divergent boundary.

Trenches are formed by subduction, a geophysical process in which two or more of Earth's tectonic plates converge and the older, denser plate is pushed beneath the lighter plate and deep into the mantle, causing the seafloor and outermost crust (the lithosphere) to bend and form a steep, V-shaped depression.

Describe the causes of earthquakes and volcanic eruptions and their effects on people and the environment

Key vocabulary

Geo thermal Tsunami Mudflows Geological structure

Lahars National park Food web Floods

Geo thermal: The heat from inside the earth

Tsunami:  A sea or tidal wave triggered by an undersea earthquake or volcanic eruption that displaces the water above it setting up a series of waves that build up to form a powerful devastating wave at the coast.

Mudflows: A mass movement of soil and rocks down a slope that is often triggered by heavy rain. Volcanic ash often develops into mudflows.

Geological structure: It is the study of the permanent deformation and rock failure as a result of the powerful tectonic forces.

Lahars: A volcanic mudflow that contains a mixture of rocky debris, ash and water. It usually flows down a river valley from a volcano.

National Park: A park created by a country to protect the plants, animals that live inside them or the land itself.

Foodweb:  Food webs show how plants and animals are connected in many ways to help them all survive

Causes:

Build up of pressure that results from plate movement:

1)      Plates move at a slow rate  averaging 40mm per year. This means that volcanoes that were created where two plates met will be carried along on the plate and away from the plate boundary.

2)      Different geological structures: These structures cause vertical weaknesses, or faults to occur. Some places beneath the Earth’s crust are hotter than others and are called hotspots.

Effects/Impacts:

On People

	Positive (opportunities)	Negative
Earthquakes	·         Underground minerals may be brought nearer to the surface	·         Kills people and wildlife ·         Destroys buildings ·         Destroys roads, railways and infrastructure ·         Can create tsunamis
Volcanoes (GMINT)	·         G - Can be used for Geothermal energy ·         M - Lot of minerals like Gold, Diamonds etc are available which are precious ·         I - Brings in Income for locals and country ·         N - Light ash falls can add nutrients to soil and make it fertile ·         T - Attractive for tourists	·         Engulfs settlements ·         Kills people and wildlife ·         Can destroy farms and woodland ·         Heavy ash can cover area in thick layers and cause roof collapse ·         Ash can cause problems for aircrafts ·         Can destroy buildings and transport infrastructure ·         Gases can cause pollution

On Environment

è The heat from the eruption melts glacial ice which can cause floods, mudflows and lahars

è The lava flows into the forests and crops and destroys them

è The volcanic bombs, explosion of rocks can kill the animals and in turn can affect the local food webs

è The ash causes air, water and land pollution. It can also acid rain.

Demonstrate an understanding that volcanoes present hazards and offer opportunities for people

Key vocabulary

Caldera Ring of Fire Hazard Opportunities

Vineyards Renewable Crystallize Volcano tourism

Caldera: The crater left after a volcano blows its top off

Ring of Fire: It is a string of volcanoes and sites of seismic activity, or earthquakes, around the edges of the Pacific Ocean.

Hazard: A potentially dangerous event or process. It becomes a disaster when it affects people and their property.

Renewable: Can be used again and again

Crystallize: Forming crystals

Volcano tourism: Tourism promoted to view volcano related activity. Hawaii, the azores islands, Iceland and New Zealand promote this a lot

Pyroclastic flow: are superhot(700°C) flows of ash and pumice (volcanic rock) moving at speeds of 500 km/hr.

Cinders: are small rocks and coarse volcanic materials.

Hazards associated with volcanic activity

Direct hazards	Indirect hazards	Socio-economic Impacts
·         Pyroclastic flows ·         Volcanic boms ·         Lava flows ·         Ash fallout ·         Volcanic gases ·         Lahars ·         Earthquakes	·         Atmospheric ash fallout ·         Landslides ·         Tsunamis ·         Acid Rainfall	·         Destruction of settlements ·         Loss of life ·         Loss of farmland and forests ·         Destruction of infrastructure – roads, air strips and port facilities ·         Disruption of communications

Earthquakes hazards and impacts

Primary hazard	Secondary hazard	Impacts
·         Ground shaking ·         Surface faulting	·         Ground failure and soil liquefaction ·         Landslides and rockfalls ·         Debris flows and mudflows ·         Tsunamis	·         Total or partial destruction of building structures ·         Interruption of water supplies ·         Breakage of sewage disposal systems ·         Loss of public utilities such as electricity and gas ·         Floods from collapsed dams ·         Release of hazardous material ·         Fires ·         Spread of chronic illness

If volcanoes are dangerous, why do people still live there?

-It might be that people living there understand the environment and they feel the benefits outweigh the risks

-Some people live because they have very little choice over where they live, as they are too poor to move.

Opportunities for people (GMINT)

Geothermal:  Heat from molten magma melts rocks, and creates hot water springs and geysers. It can be used for cooking and washing, but also to generate electricity for use in houses and industry especially in cold countries like Iceland.

Minerals: Magma when crystallized releases minerals in the process. Gold, silver, copper, zinc, diamonds etc will be accessible close to the surface and easy to mine

Income: The local people and the country can earn a lot of money by volcano tourism, mines, industry running on Geothermal energy and develop its standard of living

Nutrients: Volcanic soils are fertile as the light ash provides with nutrients and are responsible for prosperous vineyards, farms and grain fields.

Tourism: Many people want to see the geysers, hot springs or an erupting volcano. Scientists may want to study the volcanoes and hence tourism is promoted in this respect

Explain what can be done to reduce the impacts of earthquakes and volcanoes

Key vocabulary

Cross bracing Evacuation

Radon gas Vulcanologists

Managing Earthquakes : Do nothing, adjust or leave the place

The main ways of dealing with earthquakes include:

Better forecasting and warning	Building design, building location and emergency procedures
·        Measuring small scale movement of plates ·        Noting strange and unusual animal behavior ·        Checking historic evidence in some frequently occurring regions	·        Building design – Deep foundations, Damping and bracing, wide concrete pillars, shock absorbers, pyramidal structures with heavy top ·        Building location – Avoiding fault zones and soft soils, not building too close together ·        Preparation: Trained rescue teams with emergency services

Managing Volcanoes

There are a number of ways in which the impacts of volcanic eruptions can be reduced. These include:

·         Spraying lava flows with water to cool them down and cause them to solidify

·         Digging diversion channels to divert lava flows away from settlements

·         Adding ‘cold’ boulders to a lava flow to cool the lava and stop it moving

Predicting volcanoes

·         Monitoring for steam and gas rising out of a crater and small lava flows

·         Using seismometers to record swarms of tiny earthquakes that occur as the magma rises

·         Using chemical sensors to check the change in the chemical composition of air and water around the volcano

Case study – An Earthquake - Haiti

1)      Explain the causes of an earthquake which occurred in a named area which you have studied.

(Intro and PSR for both causes and effects)

Haiti is in the Caribbean with the Atlantic Ocean to its north and Caribbean Sea to its south. It shares an island with the Dominican Republic on the western side.

On 12th January, 2010, a catastrophic magnitude 7.0 earthquake occurred. The epicenter was just 16kms south-west from the capital city, Port-au-Prince and the focus was only 10kms below the surface. It was a shallow –focus earthquake.

Haiti lies close to the conservative plate boundary. The North American plate was moving westwards and the Carribean plate was moving eastwards.

As the two plates were grinding past each other in opposite directions, the earthquake was caused by the release of seismic stresses that had built up around the two plates.

Since Haiti is very close to the boundary , many fault lines linked to the plates' movements run right through the country and caused intense shaking contributing to the high scale of devastation.

2)      Name an area which you have studied where there has been an earthquake. Describe the effects/impacts of this earthquake.

It caused a severe damage over a large area. Buildings like Houses, airport control tower, hospitals, schools, orphanages, hotels, palace, Parliament buildings, etc. were destroyed. The different types of infrastructure like Roads, airport, port, water supply, telephone network, etc. were damaged.

Over 2,20,000 people were killed. Over 2,50,000 houses destroyed and over 3 million people were displaced. With over 1300 schools being destroyed, children could not go to schools.

The landslides damaged the dam which caused flooding and the dirty water caused water borne and water bred diseases like cholera, malaria and diarrhea

Haiti being one of the poorest countries and over 80% of the population below the poverty line, its economy suffered a huge loss. The total damages of this tragedy was estimated to be $7.8 billion

Case study – A Volcano – Mount Sinabung, Indonesia for causes

1)      Explain the causes of an eruption of a named volcano which you have studied. You may use labelled diagrams in your answer.

Mount Sinabung is to the north-west of the narrow island of Sumatra. The Strait of Malacca is to the east and the Indian Ocean to the west. This volcanic mountain was dormant for over 400 years until it erupted in late August 2010. It erupted again in September 2013 but in February, 2014, vast quantities of rock, toxic gas, and ash exploded out of the crater. Recently, on September 27th, 2017, it spewed plumes of ash and smoke 2.5km into the air.

At the destructive plateboundary, the Indo-Australian plate is approaching from the west and sliding beneath the Eurasian plate. Rocks from the subducting plate are heated and melt, becoming magma.

As the amount of magma being created builds up, this caused pressure under the ground which is released and magma is forced up through lines of weakness in the crust, leading to the eruption of this volcano.

Sinabung is located on the 'Ring of Fire', a volatile zone of seismic activity with hundreds of active volcanoes and 90 per cent of the world's earthquakes.

Case study – A Volcano – Mount St. Helens for effects

2)      For a named example of a volcanic eruption you have studied, describe its effects on people and the natural environment.

Mount St Helens is an active strato-volcano in Washington state, USA. An earthquake of 5.1 magnitude triggered a massive eruption on 18^th May, 1980. It was so powerful that the volcano’s height was reduced by 390 meters and a crater (caldera) 3km wide and 640 meters deep was created on the northern slope.

Effects on people : Despite the warnings, 57 people died. 200 houses and Crops (e.g. wheat, alfalfa and apples) were destroyed.

Effect on infrastructure: 27 bridges, 24km of railways, 298 kms of roads were destroyed and Interstate 90 highway and the airports were closed.

Effects on the environment: Ash rose upto 24km and landed in 11 states. The melted ice caused a mudflow that travelled over 80 km to the south-west. Nearly 400 km² of forests were destroyed. 1500 elks and 500 deer perished.

The loss was expected to be US$860 million.

Case study – A Volcano – Mount Merapi for opportunities

3)      For a named area you have studied, describe the opportunities provided by volcanoes.

Mount Merapi is an active strato-volcano located on the border between Central Java and Yogyakarta, Indonesia. It is the most active volcano in Indonesia and has erupted regularly since 1548. Merapi continues to spew clouds of ash and noxious gases, with bits of volcanic debris rea ching as far as Yogyakarta, the region’s  largest city, 20 miles away.

Fertile soils: Yet residents here have chosen to face the risk rather than move away. The short-term destruction of eruptions like the one now is more than outweighed by the long-term benefits of the nutrients that ash falls bring to soils. Thousands of Indonesians live in small villages farming on the volcanic slopes because of the fertile soils and abundant rainfall. Food is needed as Indonesia is one of the most densely populated places.

Tourism: During its resting time of volcanic activities, it will enable those who have much interest in mountaineering to have fun and to make them more acquainted with the flora of its tropical rain forest. From the observation post located on Plawangan hill tourists can see the incredible sights of molten rocks oozing over the rim, sometimes accompanied with hot lava pouring out regularly and leaving a long trail of smoke.

Culture:The rich soils allowed for settled agriculture and food surpluses that, in turn, allowed to the specialization of artists, bureaucrats, and other workers who created ancient Java's temples and culture.