1.Tectonics

The global distribution of tectonic hazards can be explained by plate boundary and other tectonic processes

• The global distribution of earthquakes, volcanic eruptions, and tsunamis

  • All plate boundaries have earthquakes

  • There are more earthquakes at convergent plate boundaries

  • Tsunamis occour around destructive plate margins

  • A lot of these occour around the Ring of FIre

  • Intraplate earthquakes are infrequent

  • Destructive plate boundaries have the most volcanos

• The distribution of plate boundaries resulting from divergent (constructive), convergent (Destructive), and conservative (Transform) plate movements

  • Continental Plates are old

  • Oceanic plates are young

  • There are loads of divergent plate boundaries in the Southern and Atlantic Oceans

  • This suggests that oceanic plates are created in oceans

  • Convergent boundaries tend to be on the coast, where continental and oceanic plates meet

  • Constructive plate boundaries are infrequent

• The causes of intra-plate earthquakes and volcanoes associated with hot spots from mantle plumes

  • Magma is molten rock

  • Warm magma rises

  • The core of the Earth is 2300 degrees

  • As the magma rises, it cools, causing it to sink

  • These cause convection currents, moving the plates

  • Where they rise, these form hot spots from forming mantle plumes

There are theoretical frameworks that attempt to explain plate movements

• The theory of plate tectonics and its key elements

  • The earth is made of:

    • A dense solid inner cire

    • A dense liquid outer core

    • A mantle of molten rock

    • A crust

  • Mantle convection is the heat from the earth’s core rising and falling in convection currents

  • The outer core is liquid iron and convects

  • This movement creates a magnetic field for the earth, which can change direction

  • Rock is trapped in the magnetic field of the time it was created, called palaeomagnetism

  • Denser plates can move under less dense plates, causing subduction and slab pull

  • Seafloor spreading is the continuous input of magma when the plates seperate

  • Ridge push is when the ground of colliding plates go into each other pushing up mountains

• The operation of these processes at different plate margins

  • Destructive-Subduction and slab pull occours with denser plates subducting under lighter plates

  • Constructive-Seafloor spreading occours as the plates are moving away from each other

  • Collision-Ridge push occours as the plates move into each other without subducting

  • Transform- As plates move alongside each other, they pull on each other causing friction

• Physical processes impact on the magnitude and type of volcanic eruption, and eathquake magnitude and focal depth

  • Volcanoes

    • Convection currents and sea floor spreading causes magma to rise and create volcanoes

  • Eathquakes

    • Any plate movement causes earthquakes

    • Subductions and slab pull increases pressure, with the benioff zone having pressure built up on it

Physical processes explain the causes of tectonic hazards

• Earthquake waves cause strucral fracturing, ground shaking, and secondary hazards

  • P waves (push pull) are faster, smaller waves which give warning to more destructive waves coming

  • S (up down) waves move slower with more energy

  • Love (side to side) waves are the most destructive, worst on hard ground

  • The further away you are, the more warning you get

  • Liquifecation

    • The earthquakes cause loose unconsolidated materials to get seperated

    • No longer a problem due to the amount of spending, with building now being built to withstand it

  • Landslides

    • Earthquakes disturb the ground

    • This causes the ground to slide, destroying infrastructure in hilly areas

• Volcanoes cause lava flows, pyroclastic flows, ash falls, gas eruptions, and secondary hazards

  • Lava Flows

    • More viscous areas have more silica in

    • More water disolved means there is more gas to escape

    • Low V low G- Lava spreads far and wide over the surface

    • High V low G- Lava moves out slowly forming a bulbous dome

    • Low V high G- Froths quickly, sending cinders that cool quickly and fall to the ground

    • High V high G- Gases quickly escapes, forming red hot lava froth, and superheated steam

  • Pyroclastic Flows

    • Ash from volcanoes explodes out

    • Can’t escape it as it is too fast

    • Is very hot fire dust

  • Ash Fall

    • Huge amounts of ash suffocates plants, damages agriculture, and pollutes water

    • Wind direction affects ash falls

    • Clumps together to form pumice

    • Is heavy when wet

    • When hydrated, can mobilise to form a lahar, moving fast being dangerouse

  • Gas Eruptions

    • Lake Nyos

    • Gas eruption under a lake

    • Stuck under pressure usually

    • Volcanic activity pushed gases up

    • Gas went out of the lake, suffocating nearby villages

    • They now pump the water to stop this from happening again

• Tsunamis can be caused by sub-marine earthquakes at subduction zones as a result of sea bed and water column displacement

  • Causes

    • Undersea earthquakes at subduction zones

    • Violent undersea volcanic eruptions

    • Major underwater landslides

  • Have much longer wavelengths than normal sea waves

  • Height grows when they get closer to land

  • Sometimes occour hours apart

  • Dependant on the amplitude and distance travveled, as well as funnel shape of coasts

Disaster occourence can be explained by the relationship between hazards, vulnerability, resilience, and disaster

• Definition of a natural hazard and a disaster, the importance of vulneribility, and a communities threshold for resilience, the hazard risk equation

  • A hazard is a natural event that has the potential to cause damage, injury or death

  • A disaster occurs when a hazard seriously affects people and property

  • Vulnerability is how susceptible people are to the hazard

  • Resilience is the ability to resist, cope with and recover from hazards

  • Threshold is the point at which a hazard becomes a disaster

  • Hazard Risk = Hazard times Vulnerability divided by Capacity to Cope

  • Japan

    • High hazard risk due to location on the Ring of Fire

    • Low vulnerability due to wealth and preparation

    • High resilience due to strong economy and emergency services

  • Haiti

    • High vulnerability due to poverty

    • Low capacity to cope

    • Very low resilience

    • Hazard became a major disaster

  • Mt Pinatubo

    • Vulnerability reduced through evacuation

    • Capacity to cope increased through US and government support

    • Disaster impacts reduced despite huge eruption

• The pressure and release model and the complex interrelationships beween the hazard and its wider context

  • Disasters occur when hazards affect vulnerable people

  • Root causes create vulnerability

  • Dynamic pressures worsen vulnerability

  • Unsafe conditions increase risk

  • Root Causes

    • Poverty

    • Poor governance

    • Inequality

    • Lack of education

  • Dynamic Pressures

    • Rapid urbanisation

    • Lack of planning

    • Poor infrastructure

    • Population growth

  • Unsafe Conditions

    • Weak buildings

    • Living on hazard-prone land

    • Lack of emergency services

• The social and economic impacts of tectonic hazards on the peaople economy and environment of contrasting locations in the devekioed emerginf and developing countries

  • Social

    • Japan

      • Nearly 20,000 dead or missing

      • Over 450,000 people evacuated

      • Communities destroyed by tsunami

    • Haiti

      • About 230,000 deaths

      • 1.5 million made homeless

      • Disease outbreaks in camps

    • Mt PInatubo

      • Around 850 deaths

      • Over 1 million people affected

      • Thousands made homeless

  • Economic

    • Japan

      • Cost about $235 billion

      • Ports, roads and factories damaged

      • Power shortages after Fukushima accident

    • Haiti

      • Damage estimated at $8-14 billion

      • Government buildings destroyed

      • Major loss of jobs and businesses

    • Mt Pinatubo

      • Over $700 million damage

      • Farmland destroyed

      • Clark Air Base abandoned

  • Environmental

    • Japan

      • Tsunami caused coastal flooding

      • Fukushima nuclear contamination

      • Large amounts of debris washed into the Pacific

    • Haiti

      • Landslides triggered

      • Huge amounts of rubble produced

      • Water supplies contaminated by debris

    • Mt Pinatubo

      • Ash covered huge areas

      • Lahars continued for years

      • Global temperatures fell by about 0.5°C

Tectonic hazard profiles are important to an understanding of contrasting hazard impacts, vulnerability, and resilience

• The magnitude and intensity of tectonic hazards is measued using different scales (MMS, mercalli, VEI)

  • Mercalli

    • Measures observed effects and damage

    • Scale I-XII

    • Varies depending on location

    • Higher scores where more damage occurs

  • VEI

    • Measures size of volcanic eruptions

    • Scale 0-8

    • Based on ash volume, plume height and eruption duration

    • Each increase = roughly 10x larger eruption

  • MMS

    • Measures energy released by an earthquake

    • Logarithmic scale

    • Increase of 1 = 10x greater ground movement

    • Replaced the Richter Scale

• Comparing the charicteristics, volcanoes, and tsunamis (magnitude, speed of onset,duration, frequeny, spatial predictability) through hazard profiles

  • Earthquakes have a sudden onset, short duration, difficukt to predict, occour frquently over large areas

  • Volcanoes have a slower onset but are more predictable with localised impacts

  • Tsunamis are triggered by undersea earthquakes

  • They are rare but rapid and highly destructive

  • Japan had a quick onset for the earthquake but a slower one for the tsunami

• Profiles of earthquake volcano and tsunami events following the severity of socioeconomic impact in developed, emerging, and devolping countries

  • Japan

    • Nearly 20,000 dead or missing

    • Hundreds of thousands evacuated

    • Communities destroyed

    • Nearly 20,000 dead or missing

    • Hundreds of thousands evacuated

    • Communities destroyed

    • Strict building regulations

    • Advanced warning systems

    • Strong emergency response

  • Mt Pinatubo

    • Around 850 deaths

    • More than 1 million people affected

    • Large-scale evacuations

    • Crops and buildings destroyed

    • Significant damage to infrastructure

    • Clark Air Base abandoned

    • Successful forecasting

    • International cooperation

    • Effective evacuation programme

  • Haiti

    • About 230,000 deaths

    • 1.5 million homeless

    • Health and sanitation crisis

    • $8-14 billion damage

    • Government buildings collapsed

    • Economic activity severely disrupted

    • Poor building quality

    • Poverty and overcrowding

    • Weak emergency response capacity

Development and governance are important in understanding disaster impact and vulnerability and resilience

• Inequality of access to education, housing, healthcare and income opportunities can influence vulnerability and resilience

  • Mt Pinatubo

    • Poor quality of housing with flat roofs collapse due to the heavy ash

    • Stilt houses survived laahrs

    • Richer people were able to move and avoid lahars

  • Japan

    • Lack of inequaility in Japan

    • Very equal country

    • Everyone affected evenly

    • Cultural cohesion helped with reaction

  • Haiti

    • Poorest country in the western hemisphere

    • HDI 147/169

    • Half the population have no acces to toilets

    • Loads of people forced to move to Port-au-Prince

• Governance and geographical factirs influence vulnerability and a community’s resilience

  • Mt Pinatubo

    • Being allies with the USA allowed help

    • Stable government

    • Lots of people near Manila in US American AIr and Naval air bases

    • Not Particularly densely populated

  • Japan

    • Government is stable

    • A prepared government helped it

    • Didn’t hit the densest areas of Japan

    • Fairly isolated coastal regions affected

  • Haiti

    • 86% live in slum conditions

    • Dictatorships frequent in Haiti

    • Dictators give themselves a Carte Blanche

• Contrasting hazard events in developed, emergeging, and developing counties show te interaction of physical and human factors, and the importance of locational context in influencing the scale of disaster

  • Mt Pinatubo

    • On the equator, so the cooling affect of the volcano was greater

    • American airbases sparked US interests

  • Japan

    • Cities like Ofinatu are located in a bay, so the tsunami wave got funneled

    • Sendai was flatter so their was nowhere to escape

  • Haiti

    • Earthquake was under Port-au-Prince

    • Earthquake was very shallow

    • Caused incribly large shaking

    • Caused hug amounts of death and destruction

Understanding the complex trends and patterns for tectonic disasters helps explain differential impacts

• Tectonic disaster trends since 1960 in the context of overall disaster trends. Research into the accuracy and reliability of the data to interperet

  • Reported tectonic disasters increased after 1960, partly because monitoring technology, communications and reporting improved.

  • More people now live in hazard-prone areas (cities near plate boundaries), so more disasters affect large populations.

  • Death tolls do not always increase because forecasting, building design and emergency planning have improved in many countries.

  • Data reliability can be questioned:

    • Earlier records are incomplete, especially in poorer countries.

    • Small events may not have been recorded.

    • Different organisations use different definitions of a "disaster".

    • Economic losses are difficult to compare over time because of inflation.

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  • Tectonic mega-disasters can have g=regional or even global significance in terms of economic and human impacts

    • Mega-disasters are very large events with widespread impacts beyond the immediate area.

    • They can disrupt global trade, transport and supply chains.

    • Economic costs can reach hundreds of billions of dollars.

    • Human impacts include deaths, injuries, homelessness and long-term mental health effects.

        Japan 2011 (Tohoku Earthquake and Tsunami)

    • Magnitude 9.0 earthquake triggered a tsunami.

    • Nearly 20,000 people killed or missing.

    • Fukushima nuclear accident caused international concern.

    • Disrupted global car and electronics production because Japan is a major manufacturer.

    • Cost over $200 billion, making it one of the most expensive natural disasters ever.

        Mt Pinatubo 1991

    • Ash and gases reached the atmosphere.

    • Sulphur dioxide reflected sunlight, causing a temporary global cooling effect of about 0.5°C.

    • Demonstrates how volcanic eruptions can have worldwide environmental impacts.

• The concept of a multiple hazard zone and how link hydro meterological hazards some times contribute to a tectonic disaster

  • A multiple hazard zone is an area exposed to several natural hazards.

  • Tectonic hazards often trigger secondary hazards.

  • Hydro-meteorological hazards (water and weather-related hazards) can worsen tectonic disasters.

  • Japan 2011:

    • Earthquake

    • tsunami

    • Fukushima nuclear crisis.

  • Mt Pinatubo 1991:

    • Volcanic ash mixed with heavy monsoon rain, creating lahars (volcanic mudflows) for years after the eruption.

  • Mt Etna:

    • Eruptions can trigger landslides and ash fall that affect agriculture and transport.

  • Hawaii:

    • Volcanic activity can produce lava flows, earthquakes and landslides together.

  • Haiti 2010:

    • Earthquake damage was worsened by poor sanitation and later disease outbreaks.

Theoretical frameworks can be used to understand the predication, impact, and management of tectonic hazards

• Prediction and forecasting accuracy depend on the type and location of the tectonic hazard

  • Volcanoes are generally easier to predict than earthquakes

  • Scientists monitor seismic activity, gas emissions, ground deformation and temperature changes

  • Earthquakes are difficult to predict accurately because they occur suddenly

  • Tsunamis can often be forecast after the triggering earthquake occurs

  • Wealthier countries tend to have better monitoring and warning systems

  • Haiti

    • No reliable way to predict the earthquake

    • Limited monitoring equipment

    • Little public preparedness for a major earthquake

  • Japan

    • Japan has one of the world's most advanced monitoring systems

    • Earthquake warning gave people seconds of warning

    • Tsunami warnings were issued, but waves broke barriers

  • Mt Pinatubo

    • USGS monitored increased seismic activity

    • Sulphur dioxide emissions increased before eruption

    • Over 200,000 people evacuated before the main eruption

    • Accurate forecasting greatly reduced deaths

• The importance of different stages in the hazard management cycle: Response, Recovery, Mitigation, Preparedness

• Use of Park’s model to compare the response curve of hazard events, comparing areas at different stages of development

Tectonic Hazard impacts can be managed by a variety of mitagation and adaptation strategies, which vary in their effictiveness

• Strategies to modify the event include land use zoning, hazard-resitant design, and engineering defences

  • Lava Diverging

    • Building barries

    • Moves the lava to a different location

    • At Mt Etna, was used to protect ski resort

  • Land Use Zoning

    • Protected people from tsunamis by keeping them on the dry side of the wall

    • Low quality buildings placed on the wet side

    • When the wall got burst, it kept water in, making afffects worse

• Strategies to modify vulnerability and resilience include hi-tech monitoring, prediction, education, community preparedness, and adaptation

  • Mt Pinatubo

    • USGS did forecasting around the volcano so they knew when to evacuate

    • Seismographs located small earthwuakes

    • COSPECS measured the amount of sulphur dioxide (But was it helpful)

    • You can only prepare for somthing that happens often, however

    • Evacuated a 6 mile radius around the mountain

    • Didn'‘t protect from the lahars

    • Damage could’ve been much greater, only costing 3 million

  • Japan

    • The many earthwuake centre can tell where an earthquake happens

    • They look for seismic gaps, where an earthquake hasn’t happened in a long time

    • Developed country means there was large amounts of histrical data

    • Buildings are designed to be aseismic

    • People know what to do in an earthquake

    • National disaster prearedness day

  • Haiti

    • There was no prepareation

    • Country is too poor and poorly governed

    • Country hadn’t had an earthquake in recent history