Option D geophysical hazards

intermediate focus (classification of earthquakes)

- 60-300km focal depth - frequency of occurrence decreases rapidly with increasing focal depth (more deep, less frequent earthquakes) - lower strength as shock waves travel over longer distances - release 12% of all earthquake energy

deep focus (classification of earthquakes)

- >300km focal depth - usually at subduction zones where crust deeper (Benioff zones - dip into earth) - release 3% all earthquake energy

methods to predict earthquake

- MATHS AND ALGORITHMS: look at magnitude and frequency of previous earthquakes, can notice trends (negative correlation), e.g. realising major quake occurs every 100 years, sensible to predict quake if a major quake has not occurred in 120 years - TECH, INSTRUMENTS high-risk areas known e.g. Parkfield, California (on San Andreas Fault), intensively continuously studied w/ magnetometers (measure changes in Earth's magnetic field due to stress changes in crust), laser geodimiters (measure slightest movement b/w tectonic plates), scientists quickly identify irregularities, predict - SEISMIC GAP THEORY stating that over long time, all parts of plate boundary must move by almost same amount, so if one part has not moved whilst others have, strong likelihood of quake occurring (used successfully to predict Loma Prieta segment of San Andreas fault moving, quake 1989) - ABNORMAL ANIMAL BEHAVIOUR earthquakes release high carbon monoxide, affecting large deep-sea creatures e.g. catfish small emission occur before big quakes, leak through gaps in crust to harm/kill fish, force them to surface e.g. 2011 Japan - 20 catfish waved up in beaches where later earthquake and tsunami occurred can only be used by coastal areas note: can never get any real exact prediction: focus usually 15km deep (inaccessible), changes in rock, stress, water are very complex, difficult to find one precursor (observable variable) to all events/interactions occurring earthquakes can occur w/o warning e.g. 1994 Northridge quake (LA, America), quake not predicted, occurred on fault scientists did not know existed, sudden onset

Differential earthquake impacts b/w Japan and Haiti

- both weekday, afternoon - $300 billion damage Japan > $14 billion damage Haiti (wealthier countries face higher immediate costs due to large infrastructure investments) BUT % of GDP means Haiti more damaged (only 4% Japan GDP, but near 200% of Haiti's GDP) - 9.0 Japan magnitude > 7.0 Haiti magnitude - earthquake struck in area of Haiti key to economy, but Japan earthquake in relatively isolated, vastly rural region - high buffering capacity of Japanese economy, no buffering capacity in Haiti - Japan recovered in a year (almost reached normality), Haiti still recovering currently

internal heating (mechanism of plate movement)

- bottom part of crust hotter than top (heat difference) - bottom expands (hot) - top contracts (cool) - different rates of expansion - causes stresses and bending of earth's crust, creates slopes, drag (gravity can act - main driving force of plate tectonics)

shield volcano

- convex sides, smaller - broad, gently sloping sides (lava) - constructed out of fluid, runny, basaltic, smooth lava eruptions (low viscosity), travel far distances (forming wide shape) - explosions are not explosive, lava can get to surface easily and spreads out easily, forms lava fountains - continuous flow of lava e.g. Mauna Loa

political factors affecting geophysical hazard risk

- corrupt government failing to keep strong building codes/developed infrastructure e.g. earthquake resistant buildings e.g. 2008 criticism for Sichuan govt as school buildings collapsed, govt buildings remained standing - effective lines of communication linked to govt can ensure rapid response, emergency personnel made available, prepared beforehand if govt had been proactive and monitoring event closely e.g. via seismographs, predictions e.g. Sichuan govt, China, effectively called for oversees aid in advance - govt failing to plan and regulate land use effectively, failing to inform population of risks, move away from unsafe areas

human triggers of earthquakes

- dam building and resultant reservoir formation (extra water pressure in microcracks in ground under reservoir) e.g. Katse dam, Lesotho - mining and quarrying, resource extraction, causing land movements - underground bomb testing activities e.g. North Korea

cinder volcano

- made of cinders (same uniform material), loose tephra - straight sides, steep - smaller, circular - bowl-shaped crater at summit - produce basaltic lava with high levels of trapped gas which creates explosions and breaks/splits lava into smaller pieces (tephra), produces piles of lava rock around vent - slightly thicker than shield volcano e.g. Paricutin volcano Mexico

distribution of mass movement

- mountainous areas (more slopes available) e.g. Andes in South America, Himalayas - plate boundaries (more fold mountains, earthquakes causing shaking and movement of earth materials, break loose) - high rainfall areas (more precipitation, more saturated soil) e.g. Indonesia

associated secondary hazards w/ primary hazard of volcanic eruption

- pyroclastic flows: RAPID, high speed avalanche/downward flow of superheated ash, rock fragments, dust heat melts snow and ice, liquify lung tissue before hitting humans - lahars: fast-flowing mud (mix of ash, snow and ice - melted by eruption, and water) flow high amount of dust in atmosphere (rise due to hot air), form condensation nuclei (water droplets form around small particle) causing rain - forming lahar highly destructive to those living along river channels - landslides - lava: slow-moving molten rock flow, less human deaths caused avoidable/redirectable (move away from villages) - volcanic bombs largest rock pieces ejected out volcano - tephra small lava pieces ejected out volcano, solidify before hitting ground - geysers superheated groundwater in aquifers, steam forced to surface - acid rain gas(chemicals) e.g. SO2 and water in atmosphere, damaging human health, impacting soil and water supply, corrosion of farm equipment and utility lines - rapid snowmelt/flash floods: tall volcanoes have snow-capped tops (built up snow), all instantaneously melts due to heat

convection currents (mechanism of plate movement)

- rock near hot core in mantle rises (heated, less dense) - spreads sideways/diverges when reaching crust/lithosphere, stresses lithosphere, causes split - drags plate along in direction of movement, plates slowly drift apart (slow motion) - hot molten rock cools, less dense, sinks to lower mantle currently theory out of favour, modern imaging techniques unable to identify in mantle

geographic factors affecting geophysical hazard event impacts

- rural/urban location: urban area e.g. Tokyo has higher population and building density, earthquake would inflict more damage rural areas more likely to have higher degree of isolation, causing less damage - time of day: event occurring at busy time e.g. rush hour, causing more deaths than quiet time, more people in industrial/commercial areas, more people at home at night (affects impact of earthquakes, but less so volcano) - type of buildings: HICs w/ higher quality, earthquake-resistant, insurance cover (aiding recovery after event), LICs lacking strict construction standards - depth of focus, aftershocks - economic development (e.g. similar magnitude of 2010 Haiti earthquake and Christchurch earthquakes 2010-11, but more buildings and life loss in Haiti)

effective early warning dependent on

- science and tech - communications systems - people's ability to interpret and understand warning

physical and human causes of mass movement

- slope angle: (PHYSICAL) gravity pulling material downwards (angle of slope correlated to speed of movement) - earthquakes: (PHYSICAL) ground shakes due to energy release, portions of hillside/mountain come loose - lack of vegetation: (PHYSICAL/HUMAN deforestation) vegetation usually anchors/stabilises soil, soil easily dislodged if deforestation occurs less vegetation also reduces interception of rainwater, increasing water in soil - water: (from HUMAN irrigation/PHYSICAL rainfall) makes soil more mobile, fluid, creates slip-surface, adds additional weight, helps move material downslope river at bases of cliffs can erode, undercut - geology (PHYSICAL) DIP/ANGLE of rock strata affects movement e.g. if angle directed down toward edge, more likely to cause mass movement (creates slope/slip slide) NATURE/TYPE of strata rain falls, penetrates through permeable sandstone (1st layer) and porous pebble stone (2nd layer, can store water), stops at impermeable clat - water builds up in porous rock, becomes heavier and unstable, can move. Water leaks out of spring at side of rock at cliff, but cannot escape quickly enough so builds up. Area at spring becomes wet clay (slip boundary) - becomes rotational slump (slope builds up above) other HUMAN causes: - road undercutting slope (more likely for material to slide, lack of support) - farmland at top of hill, more irrigation

aftershocks

- smaller magnitude quakes following major quake - original movement may be incomplete/ has added new stress points - rocks shift to new positions to achieve balance - frequency is roughly inversely proportional to time since occurrence of largest quake of series (less and less frequent)

associated secondary hazards w/ primary hazard of earthquake

- tsunami if underwater - liquefaction e.g. if material is soft soils/sandy areas, can behave like liquid, amplify waves - landslides e.g. rockslides, mudslides - transverse faults - building collapse - fires due to gas/electrical cable leakage - increased disease incidence due to disruption to freshwater supply

geophysical hazard event profile

- type of graph based on bi-polar score card - used to assess nature of hazard and risk presented - common way of comparing b/w hazards - line further to left = more dangerous, more risks

composite volcano

- upwardly concave slopes (sides curving inwards steeply) - composed of alternating layers of hardened lava and pyroclastic material/ash - lava emitted is gas-rich, andesitic (jam-like, sticky, viscous) - does not travel far, sticks to surface, stays still - high pressure built before eruption, explosive, plinean eruptions, produce highly eruptive columns injecting many gases and particles high into atmosphere - each eruption builds new layer on top, so produces very large volcanoes over time e.g. Mt St. Helen's

social factors affecting geophysical hazard risk

- well-educated population more aware of hazards associated w/ living area, make informed decisions on where to live, have higher income and can afford better quality housing and vehicles - educational programmes used to inform people of how best to react during hazard event e.g. in Japan, have reduced mortality rate caused by earthquakes - gender - lack of female empowerment in some cultures, sole carers for children/parents, more likely to fall behind, may not have means to escape

shallow focus (classification of earthquakes)

- within 60km of Earth's outer surface - majority of all earthquakes - strongest (close to epicentre), as wave travels through crust, loses energy and intensity, however if closer has lost less energy - release 85% all earthquake energy

geophysical hazard

A hazard formed by physical movement of earth due to natural internal Earth processes (tectonic/geologic) NOT climate/weather-based (e.g. not cyclones)

disaster

A major hazard event that causes widespread disruption to a community or region that the affected community is unable to deal with adequately without outside help

hazard

A threat (whether natural or human) that has the potential to cause loss of life, injury, property damage, socio-economic disruption or environmental degradation

Freetown mass movement hazards (LIC)

August 2017, Sierra Leone, rapid onset mudflows (highly mobile, carrying large boulders, tree trunks, advanced toward main river channel - Lumley Creek) Freetown (capital city, coastal, population 1 million, major financial, urban, political centre) cause: - 3 days torrential rainfall, 104cm July - construction of large homes in hillside areas weakening slopes - unrestricted deforestation for residential purposes, lack of veg cover causing unstable soil, more soil erosion, lacking rainfall interception secondary hazards: - flooding impacts on human well-being: SOCIAL: - 1100 people dead/missing, people trapped in submerged houses (mudslide occurred early morning, many at home asleep) - 20,000 people displaced - accessibility b/w communities lost due to obstruction of communication routes - Connaught Hospital exceeded carrying capacity, forcing workers to lay dead bodies on floor outside for identification - due to lack of manpower and threat of disease, bodies disrespected and buried in mass graves in Waterloo - deliberate cutting of electricity supply (to avoid contact w/water) causing power outages ENVIRONMENTAL: - loss of agricultural productivity - sedimentation of many rivers and streams impacting biodiversity - pollution of surface water storage by mud ECONOMIC: - roads, bridges, footpaths washed away vulnerability differences b/w and within communities: - poor infrastructure - unorganised/informal settlements on/near flood plains near Lumley Creek where mudflow would take route way through, houses easily damaged - unchecked development in outskirts of mountainous area, country has other priorities - drainage systems blocked by discarded waste, increasing surface runoff and more water infiltrating soil, causing mass wasting of mud - President Koroma declared national state of emergency, international appeal made for help, organisations in country acted immediately - e.g. Save The Children, Muslim Aid, provided basic food, water, personal counselling - Red Cross helped excavation and recovery efforts amidst rainfall (continuous downpours and damaged passageways disrupted and delayed relief efforts, increased chance of more mudslides) - Office for National Security advised survivors to evacuate flood-prone areas - aid workers provided purification tablets and courses on hygiene to prevent outbreak of waterborne diseases e.g. cholera

large hazard events

have low frequency, long recurrence interval, high magnitude - cause most destruction - require greatest risk management

pre-event management strategy for earthquakes

BUILDING DESIGN (not material that matters, more design, to withstand ground shaking) - taller buildings safer (falls outside of frequency of earthquake, does not go into resonance), also megastructures demand advanced design and quality materials (costly) so people more likely to test building repeatedly at every stage, do not want huge investment to be lost, designed to last long time - build on foundations built deep into underlying bed-rock, more firm - resting buildings on shock-absorbers - use local cheap materials to reinforce structures e.g. concrete houses reinforced w/ bamboo in India (looking for more efficient, new ways to use commonly available materials e.g. stone, wood) - LICs often build 100s of same low-quality design building, so making one change would go long way (building replicated) - spreading lifelines out e.g. gas line, petroleum line (not in same place, can cause explosion if ground sways) - share knowledge as places where most lives lost (LICs), least info known about preparation note: stopping all earthquake damage too expensive, but stopping enough damage that society can continue functioning is doable with time and effort

pre-event management strategy for volcanoes:

GPS CRATER MONITORING (gives warning on imminent eruptions, reduce vulnerability of population near volcano) - satellites continuously send info to receivers on Earth surface, calculate exact, accurate position of receiver on surface at any time (accuracy important when used as volcano monitoring technique) - many receivers placed temporarily around volcano forming GPS network - look at data from single receiver over time, compare position, determine whether ground surface moved (deformed crater) - combine several receivers data to see which specific areas of volcano moving, determine speed and direction - volcanic deformation used to construct model of movement beneath surface e.g. magma reservoirs, active faults - make accurate, reliable predictions of when eruptions will occur, prepare population, urge people to move LAVA DIVERSION (away from settlements) - build defensive structure (barrier wall/trench) e.g. Mt Etna 1669 eruption, townspeople of Catania directed lava away to Paterno (town) - cooling w/ water e.g. Eldfell Volcano 1973, Ireland, freezing seawater blasted via cannons toward lava, turned to stream, lava's heat dissipated (billions tonnes water use expensive)

Ponzano mass movement hazards (HIC)

Italy Feb 2017, landslide (slow), rotational slide, moving 1m/day for 2 weeks Ponzano (small village in S Italy, Abruzzo, population 200) cause: - rise in temp at end of Jan, 2m of snow on slopes melt, direct and slow infiltration of water into soil, saturation of slope - 81mm intense rainfall beginning of Feb - small-scale earthquakes in Abruzzo in recent months, increased instability of soil secondary hazards: - landslide volume 7 million m3 - collapse of several buildings, evacuation impacts on human well-being: SOCIAL: - 120 people permanently relocated within minutes, staying w/ friends/family members ENVIRONMENTAL: - agricultural movement surrounding village deemed unsafe due to possibility of further movement, impacting farming ECONOMIC: - limited damage due to small population of rural area - disruption to main road access of village, connecting to Civitella del Tronto - 35 properties economic losses vulnerability differences b/w and within communities: - minimised losses due to slow-moving nature, time for local authorities to react and safely evacuate everyone - Italy GDP per capita $32,000 - Italy's Civil Protection Dept and National Research Council set up monitors to track movement of landslide

Haiti earthquake hazards (LIC)

January 2010, magnitude 7 epicentre 25km SW of capital Port-au-Prince - strike-slip fault b/w Caribbean and North American plate (same direction movement, one moving faster than other, friction generating pressure) - no warning secondary hazards: - cholera spread due to damage to sewage system (human effluent mixing w/water supply, and increase in human dead bodies) - >45 aftershocks impacts on human well-being SOCIAL: - >200,000 deaths - 80% capital's schools damaged - 1.5 million displaced/homeless, people forced into shanty towns, limited sanitation provision, degrading health ENVRONMENTAL: - exacerbated smelly waterways and trash-filled beaches, pollution - chemical and oil leaks from damaged stores - profitable fertile land (could have been used for agriculture) used for slums, soil degradation ECONOMIC: - 30,000 commercial buildings destroyed - transport and communication networks e.g. airport, port, destroyed - 1/5 people lost jobs (due to building collapse) - structural damage to main clothing industry (manufacturing industry) - previously highly dependent on (2/3 exports) - $14 billion damage cost POLITICAL: - 25% civil servants in capital killed, crippling govt efforts to restore order - 60% govt buildings destroyed vulnerability differences b/w and within communities: - 80% in absolute poverty (<$2/day) - total lack of preparation, had not faced earthquake in over 200 years, govt did not place earthquake preparedness as priority, facing other challenges (lacking hazard perception) - lit rate 60%, people uneducated on hazards and how to react - lacking personal knowledge - low socio-economic conditions and poor infrastructure increasing vulnerability - neighbouring Dominican Republic provided emergency supplies e.g. water, medical supplies, machinery to aid search and rescue - Red Cross set up temporary field hospitals, healthcare supplies - cash/food-for-work programs, encouraging locals to clean rubble, support - improving countries first seismic hazard map, training first 2 local seismologists, Eric Calais coordinated efforts to map soil types in capital to determine how they amplify vibrations - proper building code guidelines enforced, earthquake resistant buildings built

geophysical hazard adaptation - increased government planning

LAND-USE ZONING - prevent certain land-uses e.g. densely populated buildings, construction of hospitals in known high-risk areas (e.g. fault lines, near slopes) - enforce strict building codes to reduce collapse risk - evacuating residents from volcanic areas, set up exclusion zones e.g. in Montserrat HICs: - authorities use risk maps (created using data collection from past events, geology, pop density) to control land use, control damage caused by hazards - info shared publicly, people make informed decisions LICs: - difficult to control land use in large urban areas (rapid rates of rural-urban migration, lack of resources) - high poverty level, many residents build houses illegally in marginal areas e.g. Haiti solution: int'l agencies e.g. Building Regulation for Resilience Program, aiming to improve implementation and compliance with regulations in vulnerable communities

Tohoku earthquake hazards (HIC)

March 2011, magnitude 9.0 - Tohoku, Japan (peripheral, NE coastal region) - thrust fault at subduction zone (Pacific plate going under Eurasian plate) releasing built up pressure via motion secondary hazards: - building collapse - 900 aftershocks, 60 over magnitude 6 - tsunami hour after earthquake hit coastline (sea floor thrust upward by 33 feet, propagating to sea surface and into waves), shallow coastal waters concentrated energy, increased height (40m), travelled 10km inland in Sendai impacts on human well-being: SOCIAL: - 20,000 deaths - power supply damage causing temporary blackouts, power outages - children separated from parents as earthquake struck during midday (school time) - 500,000 evacuated e.g. those living near power plant complex, kept in emergency shelter, poor living conditions, trauma, stress, psychological problmems - islands, traditional temples, shrines located on coast of Matsushima, extensive damage to recognisable natural landmarks ENVIRONMENTAL: - Fukushima nuclear power plant disaster/meltdown radioactive material transmitted via air and water left by tsunami, 4400x higher than max safety levels in water - 24,000 hectares of land, mostly rice paddies, destroyed by tsunami, salt left by seawater affecting crop production in future years ECONOMIC: - $360 billion damage cost - 650 companies forced into bankruptcy, 11,500 people w/o income - heavily reliant on nuclear industry previously (30% country's power supply), but now destroyed, need to import oil, causing record trade deficits POLITICAL: - public confidence in govt damaged, pressure caused Naoto Kan to resign, widespread criticism of handling of aftermath vulnerability differences b/w and within communities: - wealthy, used to handling natural disasters - children educated e.g. earthquake drills in school, taught to go under desk, fire dept taking children int earthquake simulation machines (to familiarise with sensation, won't panic when time comes) - personal knowledge about earthquake hazards kept by most - earthquake resistant buildings, concrete, tall, deep foundations, shock absorbers allowing building to move w/ earth, not against it - high individual preparedness, many households kept basic earthquake survival kit e.g. bottled water, dry rations, first aid kit - 10m seawalls breached by 15m high waves in Otsuchi - epicentre 70km offshore, minimising damage (not central city area) - public warnings issues since 2007, 1 minute warning advance - 100,000 members of Japanese self-defence force mobilised to deal w/ crisis, by prime minister Naoto Kan - Red Cross pledged financial and material support for Japan - search and rescue teams sent by China, India, New Zealand - boom in construction jobs and business, increased wages (reconstruction) - early 2015, work started on 3/4 planned infrastructure e.g. seawall, to protect low-lying coastal areas

pre-event management strategy for mass movement

SLOPE STABILISATION (engineering methods) - terracing of steep slopes to make more secure - drainage in slopes to reduce water build-up, less likely to fall - restraining structures e.g. gabions, stone walls, keep fallen material behind structure, away from living communities - erosion control e.g. rock armour, revetments, to minimise forces acting on bases of cliffs (minimise undercutting), make more stable EARLY WARNING SYSTEMS - looking at future weather conditions often the cause of landslides, having support system in place (infrastructure, workers) who can help if landslide occurs

pre-event management strategy for tsunami

TSUNAMI DEFENCES (sea walls, early warning systems) e.g. Dahoko coast of Japan, govt build concrete defence wall - height of wall limited by cost constraints (smaller walls cannot stop larger waves) - block/alleviate damage of tsunamis - protection from future environmental damage for locals COSTS: - visual pollution, disrupted tourism sector as views blocked

hazard event

The occurrence (realization) of a hazard, the effects of which change demographic, economic and/or environmental conditions

VEI

Volcanic Explosive Index, logarithmic scale measure strength of volcano VEI > 5 = very large, destructive explosion based on: - amount of material ejected into explosion - height of cloud created - amount of damage caused

parasitic cones

a flank vent on volcano that emits lava and pyroclastic material, from side-vent (central main vent opens onto main crater)

destructive plate margin

aka. convergent/compressional - tectonic plates coming together between oceanic plate (heavier) + continental plate (less dense) subduction zone formed (continental crust forces oceanic crust down) - deep sea trench formed at margin (ocean gets deeper) - melts oceanic crust (high temp, pressure) - magma rises up from hot mantle due to low density, erupts explosively through cracks in surface, creates volcanoes - very difficult to get out (deep underground, small cracks, very dense) - creates very violent eruptions of viscous lava - fold mountains form as continental crust pushed upwards and "heaps" e.g. circum-pacific belt (ring of fire) - active volcanos, violent earthquakes

constructive plate margin

aka. divergent/extensional - tectonic plates moving apart - rising magma through gap, solidifies, adds new material/land to plates - if oceanic moving away from oceanic plate - sea floor spreading (new crust formed) easy for magma to rise up, so creates runny, smooth lava small island chains (out of sea) formed, sometimes small volcanoes e.g. North American and Eurasian plate - Mid-Atlantic ridge (islands rising up forming island arc)

subduction (mechanism of plate movement)

aka. slab-pull - subduction zone forms, dense oceanic crust sinks into mantle, pulls slab of lithosphere along with it due to gravity (pulls away from other plates)

plumes (mechanism of plate movement)

column of magma in asthenospheric mantle (hotter than surrounding magma) rises up to lithosphere causing above lithosphere to weaken and deform (heats) - plume halted by resistance of lithosphere, can spread sideways, forming larger areas of weakness (heating) OR - magma can break through cracks in lithosphere into crust, forming volcanoes - plume stays in one place while above crust keeps moving, volcano formed moves away from plume (extinct), plume forms new volcano on empty place above, forming volcano chains (process continues) - HOW HOTSPOTS FORMED

Soufrière Hills volcanic hazards (LIC)

composite strato volcano 1997 large eruption of ash entering Plymouth (capital of Montserrat), ongoing, in Chances Peak (volcanic area in South of island) - b/w Caribbean and North American oceanic plate (subduction zone - Puerto Rico trench, destructive plate margin, 2.2cm annual movement) secondary hazards: - highly viscous andesitic lava, did not travel far, creates lava dome, becomes unstable, collapses, forming pyroclastic flows, travelled far, rapidly - lahars due to heavy rainfall impacts on human well-being: SOCIAL: - over 100 injuries, 19 deaths - both airports on island destroyed - lack of skilled labour, population fell from 10,000 to 3000 - only hospital access disrupted (damage road networks), traffic congestion - exclusion zone in South, influx of refugees to North, pressure on housing, rent increased by 70%, 1000s living in temporary shelter for years - respiratory diseases due to ash, mental health issues ENVIRONMENTAL: - animals and plants poisoned from gas emissions - vegetation, animal habitats destroyed by pyroclastic flow (farmers lost income) - marine habitats destroyed via volcanic ash reaching nearby sea ECONOMIC: - overseas relief efforts difficult to access due to loss of airports, main ports and infrastructure - tourism and agricultural industry collapse - Plymouth covered in layers of ash and mud (densely populated, all hospitals, schools, businesses, govt, central to economy) "ghost town", Brades became de facto capital - unemployment rise from 7% to 50% vulnerability differences b/w and within communities: - successive evacuations from warning eruptions in 1995 minimised deaths later (hazard perception, personal knowledge, preparedness) - wealth inequalities impacting capacity to recover, e.g. marginalised farmers not originally living in North had lost all economic assets, unable to afford housing, whereas many displaced residents had financial/social means to bypass shelters, move to alternative homes in North/overseas, access credit/savings - young families relocated overseas, elderly left behind, mental health/anxiety issues, needed to build 3 permanent residential homes response: - lack of local aid, relying overseas - UK (coloniser) donated £2500 to each adult to relocate to UK, conflict created as protest that not enough - Red Cross assistance to build evacuation camps in North - tourism industry recovering as active volcano attracts tourists - volcanic monitoring built, help from UK, US Geological Survey, satellite location GPS, monitoring pH of rain water, hazard maps to increase future resilience - MVO (Montserrat Volcano Observatory) constructed

Eyjafjallajokull volcanic hazards (HIC)

composite strato volcano, ice cap covering volcano, in Iceland 2010 eruption, VEI 4 secondary hazards: - rapid ice melt of large ice cap/glacier, causing localised flooding in southern Iceland - plume of volcanic ash and gas over 10km high, carried by winds SE toward Norway, northern Scotland, contained volcanic rock capable of clogging airplane engines impacts on human well-being: SOCIAL: - no deaths, no homes lost (no pyroclastic/far lava flow) - 800 people temporarily displaced - ash contaminated local water supplies, farmers warned not to let livestock drink from streams due to high fluoride conc (deadly) ENVIRONMENTAL: - prevented emission of 3 million tonnes of CO2 via air travel - ash deposited dissolved iron into North Atlantic, triggering plankton bloom ECONOMIC: - farms hit by heavy ash fall, agricultural land damaged - severely disrupted travel in Europe, flights cancelled between 14-21 April, loss of revenue for air operators (lost £130 million a day), people unable to reach work as stranded abroad, businesses lost money/trade - during Easter holidays when tourism levels high, disruption to tourism industry (lost £6 million a day) - waste of perishable food in trading (would have been sent to Europe), Kenyan farmers dumping stocks of fresh food, flowers (Kenya economy lost £3 billion due to European flights cancelled) vulnerability differences b/w and within communities: - high value forecast, 3 months of increased seismic activity prior eruption, volcano was well monitored allowing reparation, but exact timing unknown - only isolated farming communities and road network near hazard (no deaths, efficient response) - goggles and face masks distributed to people living near volcano quickly - people instructed to stay indoors due to ash in air

why oceanic crust younger than continental crust

continuously destroyed (at convergent - oceanic crust always one that sinks in due to higher density) and remade (at divergent) boundaries, forming new ocean crust

importance of mitigation in geophysical hazard adaptation

different types e.g. under-mitigation, optimal, over, very over optimal mitigation minimises total cost to society (expected losses from damage AND mitigation costs), under and over mitigating increases cost - uncertainty in ability to assess hazards and resulting losses causes limited capacity to determine optimal strategy to mitigation - limited resources means communities more likely to under-mitigate (better than nothing) - sensible strategies used

mass movement

downslope movement of a mass of surface material e.g. soil, rock, mud, moved by gravity

type of material affect on earthquake

e.g. Mexico city on soft bed of old lake, less dense, amplifying wave motion/vibration as moves itself "jelly-like" higher density of material increases wave velocity

characteristics of slides

e.g. landslide (sudden falls of rock), avalanches (sudden falls of snow) liquidity: dry (no water) speed of onset: extremely fast duration: rapid, instantaneous, short event extent: fairly small area reached frequency: frequent in mountainous areas, infrequent in other areas - large amounts of rock break loose, move quickly, high force - rocky material may block river/stream, create natural dam - highly destructive to homes, often in semi-arid climates

characteristics of falls

e.g. rockfalls abrupt movements of masses of geologic materials e.g. rocks, boulders - NOT single unit, cascading of separate units - free-fall, rolling, bouncing - loose pieces of rock fragments influenced by mechanical weathering (causing separation of rock, discontinuities), gravity

geophysical hazard adaptation - increased personal resilience - increased preparedness and use of insurance

earthquake damage (e.g. gas leaks, fires) to homes/personal property not covered by standard home insurance policy, need to purchase separately to PROTECT PERSONAL INVESTMENT, repairs/reconstruction costs covered, may receive additional living expenses to relocate somewhere else DISADVANTAGES: - costly, need to pay annual high deductibles - financial risk to spend high money on event that may or may not occur vs more justifiable to spend money after event - may not cover other secondary impacts e.g. tsunami

geophysical hazard adaptation - increased personal resilience - adoption of new technology

earthquake early warning app (available for LA in 2019) ShakeAlertLA uses network of seismic sensors distributed throughout region - detect earthquake - dispatch early warning for expected shaking - prevent injuries and death (few seconds warning sufficient to prepare) - shares LA specific info on how to prepare/get help after major quake DISADVANTAGES: - some people may not receive alerts/wrong alerts, depend on app users quickly sharing info, cell phone carriers can be overwhelmed - in HICs e.g. California, USA, high levels of tectonic hazard monitoring, higher proportion of population have smartphone tech access (download app) - LICs lack smartphone access/use

methods to predict volcanic eruption

easier than earthquake, usually always certain signs - GPS crater monitoring - chemical sensors to measure increased sulphur levels in volcano (increase closer to eruption as SO2 released) e.g. USGS correctly predicted eruption at Mt Pinatubo 1991, evacuated area beforehand BUT, wrongfully predicted eruption at Mammoth Mountain Ski Area, California - reduced visitor numbers to resort, economic distress to local businesses - predictions not reliable enough to take measures and prepare - magnitude predicted via type of plate boundary (e.g. destructive margins have more explosive eruptions than those at hotspots e.g. Hawaii)

frequency/recurrence (intervals)

expected frequency of occurrence in years for an event of a particular size (aka. return period)

forecast

general statements about future event, commonly expressed as probability

mega disaster

geophysical hazard event killing more than 100,000 people e.g. Haiti earthquake

global geophysical hazard and disaster trends, future projections

global exposure of population and built-up surface to natural hazards rose in last 40 years - population growth (more vulnerable) especially in poorer countries e.g. Congo, Uganda, least prepared - rapid urbanisation (higher number of people living in seismic areas, near volcanoes, along coast - tsunami risk, slums and squatter settlements expanding into high-risk areas e.g. slopes - Limbe - SW Cameroon, shanty towns built at base of slopes causing more landslides due to undercutting, mostly during rainy season) e.g. Tehran on active fault line (Iran capital) expecting increased disastrous outcomes in future w/o mitigation, forecasting, warning, community preparedness, resilience

small hazard events

have high frequency, short recurrence interval, low magnitude

rifting (mechanism of plate movement)

hot asthenosphere heats above lithosphere in weaker areas (e.g. thinner lithosphere), forms volcanic bulge and horizontal stretching and vertical thinning of lithosphere - asthenosphere beneath rises, pressure decreases (more space above available), decompression - cool and brittle crust above fractures, faults develop - partial melting of asthenosphere produces magma, rises to surface through cracks, forms volcanoes - continental lithosphere breaks apart (move apart), new mid-ocean ridge formed

volcanic plug

landform made from hardened vent material/solidified lava in volcanic vent, can form volcanic dome as plug is forced upwards due to pressure underneath plug blows off eventually, forms crater, crater lake forms in space on composite volcano

rotational slide

landslide along surface curved concavely upward (slumping)

translational slide

landslide moves along roughly flat plane, straight line down block slide: large single unit/few closely related units moving downslope as coherent mass

event frequency

largely constant frequency of hazard events (e.g. earthquake, volcano) as caused by tectonic forces operating over long time-scales but increasing impacts due to more people in high-risk areas, changing land-use

slump

less dramatic downslope mass movement, move earth materials slowly down hillside moves materials as large block along curved surface - often when slope undercut (no support for overlying materials), or when more weight added to unstable slope

economic factors affecting geophysical hazard risk

levels of development and tech - level of development affects individuals quality of housing, car ownership (to escape), ability to afford insurance (wealth inequalities), rescue/relief operations - tech access meaning hazard event warnings given out easily, increased awareness through social media, mobile phones, time to escape (e.g. Japan, earthquake warnings issued via phone)

layers of Earth

lithosphere (crust and upper mantle) - less dense than asthenosphere asthenosphere (low velocity zone - "jammy") lower mantle outer liquid core inner solid core (due to high pressure)

reconstruction (post-event management strategy)

long-term, 2-5 years - priory: majorly rebuilding public and economic system, infastructure, governance functions - restore quality of life and govt stability - major permanent construction process - promote continuing human development - being communities and capital stocks back to pre-disaster levels - govt plan to reduce impacts of future events, improve safety in region, reduce vulnerability - increase self-reliance - enhanced use of communications tech to map hazards/disasters (info about scale and location of hazard distributed on map)

rehabilitation (post-event management strategy)

mid-term (1-2 years) - priority: restoring function of public services (physical and community structures) to temporarily return to normality - rubble completely cleaned - making homes safe to live in - injured moved from field hospitals to regular hospitals - mass shelter replaced w/ temporary housing

volcanoes occurring...

mostly at destructive, less at constructive, never at collision/transform

Mercalli scale

observational scale rating earthquakes according to damage/disruption caused at particular place, intensity, measures impact on human life/buldings - can have low Richter score with high Mercalli score due to poor building and construction, high population

hotspots

places where molten material from the mantle reach the lithosphere there are volcanoes, away from plate boundaries e.g. Hawaii

focus

point beneath Earth's surface where earthquake actually occurs underground - where rock breaks under stress and causes an earthquake

epicentre

point directly above focus on earth's surface

demographic factors affecting geophysical hazard risk

population structure: - youthful/ageing population more vulnerable (dependents) require someone for support, not able to escape themselves, demands more energy and time from adults, more likely to be affected themselves (e.g. 65% of deaths in Japanese tsunami 2011 aged 65+) - large number of migrants (more vulnerable), unaware of local risks, inability to communicate - increasing population densities, expanding urban areas e.g. Port-au-Prince, Haiti, more vulnerable - disabilities impair mobility and more time needed to escape, require support (e.g. mortality rate of disabled population in tsunami 2011 2x as much as normal population) - overpopulation, forces housing built on fragile physical environment/marginal areas, unconsolidated loose soil, greater likelihood of building collapse

scientific predictions

precise statement about time, place, and size of future event

P wave

primary wave, body wave (occur below Earth surface) - longitudinal (linear, one direction), compressional and extensional (rock or magma is alternately compressed and expanded, same direction as wave travel) - elastic motions at high speed, first to reach any point on Earth's surface, recorded first on seismograph - travels through solid and liquid - originate from focus

geophysical hazard risk

product of economic factors, social factors, demographic factors and political factors vary in power and impact from place to place, within and between populations, LICs more vulnerable/higher risk

possibilities of response vary from place to place

response dependent on wealth of country, aid/assistance offered and cooperation b/w different stakeholders e.g. MGOs, govt, locals also depends on availability of contingency planning, type of hazard event and magnitude

ridge-push (mechanism of plate movement)

ridge formed at constructive boundary - new rock rises (warm), builds up creating slope, at higher elevation, gravity causes downward force causing crust on either side to move sideways (new crust pushes other crust out of way) - new rock is less dense, older rock further down slope is denser (cooler, thicker) causing sinking into mantle at edge - gravity pulling sideways

Richter scale

scientific logarithmic scale of 1 to 10 used to express the energy released by an earthquake, measure intensity/manitude e.g. 2 100x bigger than 1

S wave

secondary wave, body wave (occur below Earth surface) - particle motion transverse (perpendicular) to direction of wave travel - involves shearing of transmitting rock - only travels through solid material, not magma - slower, recorded second on seismograph all earthquakes have all types of waves present

rescue (post-event management strategy)

short-term (immediate aftermath) - priority: search and rescue, locating survivors, emphasis on speed and efficiency (as number of survivors decreases with time if not located and aided) - e.g. sniffer dogs, thermal sensors to detect living bodies in wreck - provision of minimum life necessities e.g. water, to save people, emergency shelter - enhancing basic facilities and infrastructure to provide adequate services for victims e.g. clearing rubble from main areas - burying victim's bodies e.g. Red Cross humanitarian support

characteristics of soil creep

slow, steady downward movement of slope-forming soil/rock (surface layer) - movement caused by shear stress sufficient to produce permanent deformation, continuous - affected by seasonal changes (soil moisture and temp) - progressive, creates ridges liquidity: relatively dry speed of onset: extremely slow duration: continuous, over years extent: cover large areas of slope, large frequency: very common, occurs on all slopes INDICATORS: - curved tree trunks (base of tree moving downslope with soil, top grows straight up) - bent fences, tilted poles - small soil ripples/edges

foreshock

small earthquake preceding major earthquake - huge numbers of small quakes = swarm, associated w/volcanic activity most earthquakes occur w/o warning - people unsure if foreshock is actual major quake or not

conservative plate margin

strike-slip fault a.k.a. transform fault - tectonic plates sliding against eachother/side-by-side - moving in opposite directions/same direction at different relative speeds plate margins are rocky, brittle, jagged - difficult to slide - plates get stuck (sticking and sliding), build pressure, jerk forwards violently (sudden movement and release of built up huge pressure) causing earthquakes e.g. San Andreas fault (West coast of North America) - sliding causes sideways mass cracks (transform faults) - Earth cracking along lines ACROSS plate boundaries, earthquakes can also occur here (not only plate boundaries, any fault line)

earthquakes

sudden, violent movements of Earth's crust, caused by movements of rock in lithosphere - series of vibrations coming from focal point below surface of Earth, plates experience sudden release of pressure and move can occur at ALL plate boundaries (where large concentration of faults) and also away from boundaries at other faults - not always disaster (if not affecting many people) but due to population growth and increasing population densities, people moving to hazardous areas, more disastrous

Love and Rayleigh waves

surface waves (occur along Earth surface) - follow after P and S wave reached surface Love waves: involve horizontal (side to side) particle movement Rayleigh waves: involve horizontal AND vertical particle movement - as they travel, disperse into longer wave (lose energy, increase wavelength, eventually flat line) - cause most damage to humans and shaking

collision plate margin

tectonic plates coming together of same type/density e.g. both continental plates (cannot subduct each other) - forced up together at high pressure, folding and crumbling of rocks forming massive mountain chains (fold mountains) e.g. Himalayas (Indian vs Eurasian plate) - no volcanoes (crust very thick, nothing is forced down and melting)

vulnerability

the geographic conditions that increase the susceptibility of a community to a hazard or to the impacts of a hazard event

risk

the probability of a hazard event causing harmful consequences (expected losses in terms of death, injuries, property damage, economy and environment) (hazard x vulnerability/resilience - population's capacity to cope)

solifluction

type of soil creep, occurs in areas of permafrost (permanently frozen rock and soil) during summer, surface layer briefly melts, water stays on top layer, soil becomes saturated, easily moves and slides

characteristics of mudflow/lahars

unconsolidated material e.g. soil, ash, and water, occurring on hillsides with soil rich in clay and low vegetation holding soil in place high precipitation causes mudflow, follow routes of existing river channels/streams - wash out bridges, homes in path liquidity: saturated, high speed of onset: have a build-up process, so slower than falls/slides duration: long period to time (hours-days) extent: travel far distances, can spread out over large areas e.g. floodplains, after leaving confined river valley frequency: frequent in tropical areas (high rainfall, storms), mountain regions, temperate areas

seismic waves

waves of motion travelling through Earth's rock, carrying energy released during an earthquake, cause motion in material passing through e.g. lithosphere