Edexcel AS Geography Unit 1 – Global Challenges Topic 1 – World at Risk Global Hazard Patterns
Hazard Risk in Your Local Area • Looking at disaster hotspots shows that some places are at more risk than others • California and the Philippines suffer from multiple hazards, but you need to think about places closer to home • In the exam, the examiners may ask you about real or potential hazard risk in your local area.
Hazard Risk in Your Local Area • You need to be able to talk about: • Any past events that might have happened in the area you live, e.g. droughts that have occurred • Any likely future events that could happen, e.g. Landslides caused by coastal erosion • The impact of these events on people, property and the environment
Hazard Risk in Your Local Area • Researching the history of hazard events in your local area could be done by: • Researching historic newspapers • Searching online • Interviewing older residents
Greece deaths Disaster Date No Killed • Extreme temperature 20/7/1987 1000 • Earthquake 12/8/1953 455 • Earthquake 7/9/1999 143 • Earthquake 1928 103 • Wildfire 24/8/2007 67 • Extreme temperature 3/7/1988 56 • Earthquake 20/6/1978 50 • Volcano July 1956 48 • Storm March 1987 48 • Storm Νοvember 196143 • Source: "EM-DAT: The OFDA/CRED International Disaster Database www.em-dat.net - Université Catholique de Louvain - Brussels - Belgium"
Greece affectedDisaster Date No Total Affected • Earthquake 20/6/1978 600100 • Earthquake 7/9/1999 115139 • Earthquake 24/2/1981 80400 • Earthquake 13/9/1986 45300 • Earthquake 9/3/1965 30253 • Earthquake may 1967 16583 • Earthquake 1/9/1966 15123 • Earthquake 13/5/1995 15060 • Earthquake 15/6/1995 13900 • Earthquake 5/2/1966 11050 Source: "EM-DAT: The OFDA/CRED International Disaster Database www.em-dat.net - Université Catholique de Louvain - Brussels - Belgium"
Greece monetary lossesDisaster Date Damage (000 US$) • Earthquake 7/9/1999 4200000 • Wildfire 24/8/2007 1750000 • Drought March 1990 1000000 • Earthquake 24/2/1981 900000 • Earthquake 13/9/1986 745000 • Wildfire June 1998 675000 • Flood 2/2/2003 600000 • Earthquake 13/5/1995 450000 • Flood 24/10/1994 437700 • Earthquake 15/6/1995 422700 Source: "EM-DAT: The OFDA/CRED International Disaster Database www.em-dat.net - Université Catholique de Louvain - Brussels - Belgium"
Attiki natural disasters factfile Our local area has many natural hazards. • Earthquakes • Droughts • Floods • Wild fires Cause most of the deaths, injuries, damages etc. We need to think about the impact of these events on people, property and the environment. Also..Which hazard event is most likely to be repeated? How do you rate the risks of such an event?
1999 earthquake • Magnitude of 6.0 Richter • Occurred on September 7, 1999, at 2:56:50 pm local time and lasted approximately 15 seconds in Ano Liosia. • The tremor was epicentered approximately 17 km to the northwest of the city center, in a sparsely populated area near Mount ParnithaNational Park. • This proximity to the Athens Metropolitan Area resulted in widespread structural damage,
143 dead2,000 injured50,000 homeless53,000+ buildings damaged or destroyed • Northern Athenian suburbs of Kifissia, Metamorfosi, Kamatero and Nea Philadelphia worst affected. • More than 100 buildings (including three major factories) across those areas collapsed trapping scores of victims under their rubble while dozens more were severely damaged.
It was the biggest disaster in almost half a century. • This event took Greek seismologists by surprise as it came from a previously unknown fault, originating in an area that was for a long time considered of a particularly low seismicity.
Future earthquake risk? • Greece has thousands of earthquakes a year (the vast majority extremely mild) • The strict building codes are upgraded and reinforced after every major quake and this has given the Greeks a certain quiet confidence in their buildings, which translates into an almost relaxed attitude towards earthquakes. • Education pays back - learning how to prepare for earthquakes has been mandatory in all schools for some time.
This ensures that younger generations grow up knowing what to do and they then disseminate the information to their parents and into their local community.
1987 extreme temperatures • Summer of 1987 saw a heat wave with temperatures as high as 44 degrees C and low wind speeds • 1000 people died in Athens from 20-31-July – more than double the usual for this period • Smog also accompanied the heat wave so made the stress greater for the people • Elderly and retired people were particularly susceptible
2960 people were administered to 68 Athens hospitals at this period • The deaths were from heat stroke, heat exhaustion etc
2007 wild fires • 28 June 2007 - 3 September 2007 • A series of massive forest fires that broke out in several areas. • The most destructive and lethal infernos broke out on 23 August, expanded rapidly and raged out of control until 27 August, until they were put out in early September. • In total 84 people lost their lives because of the fires, including several fire fighters.8]
Some of these firestorms are believed to be the result of arsonwhile others were indeed the result of mere negligence. • Hot temperatures, that included three consecutive heat waves of over 40 °C, and severe drought rendered the 2007 summer unprecedented in modern Greek history. • From the end of June to early September, over 3,000 forest fires were recorded across the nation.
A total of 2,700 square kilometers of forest, olive groves and farmland were destroyed in the fires, which was the worst fire season on record in the past 50 years. • Many buildings were also destroyed in the blaze. The fire destroyed 1,000 houses and 1,100 other buildings, and damaging hundreds more. • Economic losses of US$ 1.75 billion
The first major fire of the summer of 2007 was started on 28 June 2007. • It is perceived to have been started by either an exploding electrical pylon or by arsonists. • Significant parts of the Parnitha National Park were destroyed and in total, the fire burnt area of 153.8 km2 making it one of the worst recorded wildfires in Attica since the Penteli fire of July 1995.
The magnitude of the devastation was unforeseen. Environmental studies in Greece report that the Athenian microclimate will significantly change to warmer during the summer season, and flooding is now a very probable danger for the northern suburbs of the city. • Mount Parnitha was considered the lungs of Athens; following its considerable burning, both the city and local flora and fauna are expected to feel the consequences.
Future risk of fires? • Attica is the highest risk zone in Greece • The high forest fire risk potential is most probably increasing due to increasing temperatures, decreasing precipitation and consequently rising drought potential caused by climate change • It is mainly due to the development dynamics of Athens conurbation – ie further urbanisation.
Athenians are moving back to countryside on the edge of the city so residential areas are intermixed in forestlands. Eg. Penteli 50% urbanised from 1940s -1990s (Varela at all, 1999). • Tourism has become a new form of land use, and has in some areas replaced traditional economic activities (farming and grazing). • Seasonable employee in tourists activities as well as tourists do not develop an attitude of responsibility towards the land they are visiting (Pyne, 1997).
Essential viewing…. • http://www.climrun.eu/elfinder_vfs/185/agu_2011.pdf
Causes of Greek fires 1968-1993 • 1. Lightning 2.4% • 2. Accidents 3.5% • 3. Negligence 36.0% • 4. Intentional(Arsons, rangeland improvement) 29.2% • 5. Unknown 28.9%
1994 Greek floods • Flooding constituted the second most frequent natural disaster in Greece during 1928–2005 (15 episodes; 23.4% of total) after earthquakes. • It led to 78 deaths, 10,990 affected people and 719,518,000 US$ damage and repair costs (World Health Organisation 2005).
Nevertheless, the 28 episodes of flooding in Attica Prefecture cost more human lives (182 people) during the last century 887–2005) than earthquakes (18 people) while the cost in human lives due to flooding for the whole country during the same period was 220 people
The increase in urbanized area led to concomitant decrease in cultivated, forested and shrub areas (was 81.3% in 1945; 31.0% in 1995). • Human interference at suburban areas of Attika included land clearance, agricultural abandonment, forest fires, unplanned expansion of urban areas, and rubble-filing for the creation of roads and plots.
Led to reduction in the infiltration of water • And to increase in erosion, surface runoff and locality-specific vulnerability to flash flooding depending on distance from streams and slope of land at Attica basin • Spasmodic, un-coordinated mainly reactive flood-prevention strategy, which does not take under consideration the anticipated increase in intensity and rapidity of rainfalls due to climate change • at Attika basin
300 mm in 24 hours 21-22 October (normally 400mm in year) • Low pressure depression arrived • 9 dead in Athens • Extensive damage to some bridges, roads etc
Hazard Distribution – Geophysical • Geophysical hazards (especially volcanoes, earthquakes and to some extent tsunamis) usually occur near plate boundaries so knowledge of plate tectonics in required.
Platetectonics • The lithosphere (the Earth’s crust and the rigid upper part of the mantle) is divided into 7 large and several smaller plates. • The plates, which are rigid, float like rafts on the underlying semi-molten mantle (called the asthenosphere) and are moved by convection currents. • Convection currents are generated by hotspots within the asthenosphere which cause magma (molten material) to rise towards the earth’s surface. • These currents can cause the plates above to move together, apart or side by side.
Crust • Plates are made of two types of crust: • Continental crust – is composed of older, lighter (less dense) rock of a granitic type • Oceanic crust - is composed of much younger, denser rock of a basaltic composition.
Hazard Distribution – Geophysical • Volcanoes and earthquakes most commonly occur at the boundaries where the plates meet. • There are three types of plate boundary – constructive, destructive and conservative. • The type of movement and the degree of activity at the plate margins almost totally controls the distribution, frequency and magnitude of earthquakes and volcanic eruptions.
Earthquakes • The main earthquake zones are clustered along plate boundaries. • The most powerful earthquakes are associated with destructive or conservative plate boundaries
Destructive Plate Boundaries – plate converge 1. An oceanic plate and a continental plate move towards each other • Eg Alongside South America is the Nazca Plate (oceanic ) and the American Plate (continental) • Also the Philippines • The oceanic plate is forced downwards as it is denser than the continental plate • This results in a subduction zone • An ocean trench forms too – (where the sea water is deeper here) • Friction occurs and the force of the compression as the plates meet causes stresses in the crust and pressure occurs as the oceanic plate subducts • When the pressure is released the point at which it is released is called the focus • The ground surface immediately above shakes • The point on the surface where the maximum damage occurs is the epicentre • The oceanic plate breaks off and melts over a long time period • Newly formed magma rises at the continental plate and forms volcanoes and fold mountains eg Andes
Destructive Plate Boundaries • 2. The same process occurs where two plates of oceanic crust are moving towards each other • The denser of the two will be subducted • e.g. This has formed the volcanic islands of Indonesia. • As one plate moves under the other they can get stuck. This causes pressure to build up. • When the pressure becomes too much the plates jerk past each other, causing an earthquake. • Sometimes the magma rises offshore to form an island arc of volcanic islands eg Caribbean islands and Japan
Destructive Plate Boundaries 3. Collision - Two continental plates move towards each other • They are of equal density so there is no subduction • The rocks are forced upwards to form fold mountains • Eg The Indian and Eurasian plates are moving together forming the Himalayas and Mount Everest is slowly growing • Earthquakes occur in these locations • eg Large areas of countries can be affected by these shallow highly damaging earthquakes eg India and Iran • There is no volcanic activity in these locations • The Kashmir earthquake of 2005 occurred in this way.
Constructive Plate Boundaries • Both volcanoes and earthquakes occur at constructive plate boundaries • Two plates move away from each other (diverge) due to convection currents in the asthenosphere • Molten magma rises to fill the gap and forms new oceanic crust through volcanic activity • Eg North American plate is moving away from Eurasian plate so Atlantic ocean is getting 3cm larger – USA and Europe are moving apart • Mid oceanic ridges are formed eg The Mid Atlantic Ridge • Islands may be visible above the water’s surface as islands eg Iceland • Earthquakes occur here due to friction and pressure release. • There are many earthquakes here. These earthquakes tend to be shallow and low magnitude as lava rises. • Most (not Iceland!) tend to be under the sea so pose little hazard to humans. • The plates do not move apart in a uniform way – some parts move faster than others. This causes pressure to build up. When the pressure becomes too much, the plate cracks, making a fault line and causing an earthquake. Further earthquakes may also occur along the fault line once it has been created.