hazards 1

whats a hazard, natural hazard and disaster

• A hazard is an event which has the potential to cause harm to the environment, people or the economy

• A natural hazard is an event caused by environmental processes

• A disaster occurs when harm actually occurs to the environment, people or the econom

give me examples of Tectonicearthquakes,+ geological hazards, cllimate and meteorological hazards and Biological hazards

• earthquakes, volcanic eruptions, landslides

• Drought Blizzard/snowstorm/sandstorm Heatwave

• pests and disease

how natural hazards can be categorized

• Magnitude - the strength/power of the event

• Frequency - how often the event occurs

• Size - the area covered by the hazard

• Duration - the time a hazard event last

what are tropical cyclones + their chracteristics

• rotating, low-pressure systems (below 950mb) aka hurricanes, cyclones and typhoons

• heavy rainfall high

• wind speeds (over 119 kmph)

• high waves and storm surge

how magnitude of cyclone is measured

Saffir simpson scale 1-5

whatr earthquakes +how do they happen

• An earthquake is a sudden, violent shaking of the ground

• Earthquakes are the result of pressure building when tectonic plates move

what the focus + epicentre of an earth quake + how to measure magnitude

• The epicentre is the point on the Earth's surface directly above the focus

• The focus is the point at which the earthquake starts below the Earth's surface

• Richter Scale or the Moment Magnitude Scal 4-10

how do volcanoes form, where do they occur + where dey found

• form when magma erupts onto the Earth's surface as lava

• constructive (divergent) and destructive (convergent) pb’s

• ctive volcanoes are located around the rim of the Pacific Ocean called the 'Ring of Fire

what are hotspots

• Hotspots occur away from plate boundaries and are plumes/columns of magma which escape through the Earth's crust

Measuring eruption magnitude

• magnitude of a volcanic eruption is measured on the Volcanic Explosivity Index (VEI)

• weird circle..?

formation of tropical cyclone

• Warm seawater (27°C or over) around the tropics

• There are high levels of evaporation and condensation of water vapour from warm water leading to cumulonimbus cloud formation

• The high levels of evaporation and condensation of water vapour provide energy for strong winds

• Strong Coriolis Force close to the equator makes winds spin and moves them away from the equator

• The tropical cyclones move westwards due to east-west winds in the tropics and strengthen as they move over warm waters

Tropical cyclones require specific conditions to form

• Sea surface temperatures over 27°C

•   Between 5° and 30° north and south of the equator

• Low wind shear

• A deep layer of humid air

• in low pressure area below 950mb

features/ characteristics of tropical cyclone

• Heavy rainfall High wind speeds (over 119 km/h)

• Storm surges 

• Calm eye

• Highest winds and heaviest rain in the wall of the eye

volcanic eruptuion n earthquakes take place give examples

• at plate boundaries there are 4 of them

• Constructive (divergent)

• Destructive (convergent)

• Collision

• Conservative (transform)

Constructive (divergent) plate boundary

• At the constructive boundary, the plates are moving apart

• The Mid-Atlantic Ridge is an example of a constructive plate boundary

• Both volcanic eruptions and earthquakes can occur at this type of plate boundary

Destructive (convergent) plate boundary

• At a destructive (convergent) plate boundary, the plates are moving together

• The denser, heavier oceanic platesubducts under the lighter, less dense continental plat (E+V takes place here)

Collision boundary

• At a collision boundary, two plates of similar density move towards each other

• Neither is dense enough to subduct, so the land is pushed upwards

• This process forms fold mountains such as the Himalayas

• Earthquakes are the main hazard at this type of plate boundary

Conservative (transform) boundary

• At a conservative (transform) boundary, the plates move past each other in opposite directions or in the same direction at different speeds

• Earthquakes are the only hazard at this type of boundar

at which plates do volcanoes often erupt in

• Volcanoes occur at constructive (divergent),

• destructive (convergent) plate boundaries

• hot spot

Volcanoes at constructive boundarie

• Constructive plate boundaries often occur under the sea/ocean

• The lava escapes through the gap left as the plates move apart

• The lava cools and hardens, forming a new crust

• At constructive plate boundaries, the lava tends to be runny and eruptions are less explosive

• These types of eruption form shield volcanoes, which have gently sloping side

Volcanoes at destructive boundarie

• The heavier, denser oceanic plate subducts under the lighter continental plate

• In the subduction zone, the two plates come together, causing friction

• Friction causes heat and the plate material melts, forming magma

• The magma rises to the surface through cracks in the crust The cooling lava and ash build up, forming a volcan

• At destructive plate boundaries, the lava tends to be sticky and produces explosive eruptions

• These eruptions tend to form composite or stratovolcanoes 

Volcanoes at hot spots

• At a hot spot, the tectonic plate passes over a plume of magma:

• The magma rises to the surface through cracks in the crust

• As the magma erupts and cools, this builds up

• Eventually, due to the buildup of cooled lava, this may rise above the surface of the water, forming an island

• As the tectonic plate moves slowly over the magma plume, a line of islands may form, e.g. Hawai

volcano primary hazards

• The hazards from the volcanic eruption itself are primary hazards:

• Ash Pyroclastic flow

• Lava flow

• Gas emissions

• Volcanic bomb

volcano secondary hazards

• The hazards created that happen as a result of the primary hazards are secondary hazards:

• Lahars Acidification

• Landslide

• s Climate change

• Fires Flood

at which plate boundaries are earth quakes stronger/weaker

• Earthquakes happen at all plate boundaries

• At a constructive (divergent) plate boundary, earthquakes tend to be weaker as the plates are moving apart

• At destructive (convergent), collision and conservative (transform) plate boundaries, earthquakes tend to be stronger

primary hazard of earth quakes

• e ground shaking

secondary hazard of earth quake

• Collapse of buildings and other structures

• Landslides

• Gas leaks 

• Fires

• Soil liquefaction

• Subsidence

• Mudflows

• Tsunam

Earthquake sequence (how it happens)

• As the tectonic plates move, they can get stuck

• Pressure builds as the plates continue to try to move

• Eventually, the plates jolt free, and the pressure is released as energy

• The point at which the earthquake starts is the focus

• The epicentre is the point directly above the focus on the Earth's surface

• The energy passes through the Earth's crust as waves, which are the earthquake

• Earthquakes can happen as a result of human activity, such as drilling into the crust or mining