Atmosphere & Mass movement Flashcards

Question

why are he hazardous impacts of tropical storms worse than tornadoes?

Answer 1

power of tropical stones is immense, impact leads to thousands dead and widespread destruction of property death toll of tornadoes rarely reaches hundreds tropical storms affect costal areas that are often densely populated (receiving high winds storm surfers and floods) - lower course of river but tornadoes produce heavy hail storms cyclones have a diameter of 500-800kn whilst tornadoes rarely exceed 10km in path and may only periodically touch the surface BUT wind speed is higher for tornadoes as can reach 500km/hr, double that of tornadoes pressure at the heart of tornadoes is 20% below normal ambient pressure

Answer 2

60-80 miles an hour

Answer 3

leads to flooding and landslides flood control measures can be put in place along rivers deforestation if slopes floodplain management can be developed to protect critical assets; building on slopes can be controlled or prevented Protective river embankments, levees and dukes should be regularly inspected for breaches and opportunities taken to plant mangroves to reduce braking wave energy Vegetation cover can be improved This helps to reduce the impact of erosion and landslides and facilities the absorption of rainfall to reduce flooding

Answer 4

deforestation building on or on top of cutting base of slopes mining or quarrying filling large resovirs weapons testing shear stress strength balance affected

Answer 5

A violent destructive weather system with powerful rotating winds up to 300km/h Intense low pressure systems Their development depends on instability in the atmosphere convergence and strong updrafts in the air

Answer 6

80% major tornadoes occur in the USA generally at their most hazardous tornadoes occur widely throughout the world from australia to birmingham

Answer 7

10-30 degrees

Answer 8

S violent destructive weather system Powerful rotating winds up to 300km/he Tornadoes are intense low pressure systems and their development depends on instability in the atmosphere convergence and strong updrafts in the air

Answer 9

January to April

Answer 10

over warm ocean area higher than 26 degrees more than 50m deep 500km both and south of equator 5 degrees in late summer when sea temperatures are at their maximum so moisture and energy enters the system via evaporation where the trade winds converge (NE and SW -NH) developing low pressure the undistrubed upper atmosphere allows the development of massive uplift of cold air is forced to rise rapidly forming cumulonimbus clouds no wind shearing the coriolis forces helps generate strong spinning winds, around the low pressure at the centre of the storm (eye)

Answer 11

Drainage pipes - hard engineering Reduce build up of water decreasing water pressure in the soil preventing oversaturation Effective, low cost covering a large volume of ground HOWEVER requires regular maintenance or it’ll become ineffective

Answer 12

less evaporation any air blown on shore is drier and cooler off coast of peru or chile cold peruvian current

Answer 13

Category 5 on the Saffir Simpson Scale Wind speeds in excess of 250km per hour Storm surge of more than 5.5m This can lead to extensive damage to property and cause deaths and injuries from flying objects

Answer 14

inherent: weaknesses in the rock structure, composition of soil caused by heavy rain or snow melt caused by tectonic or seismic activity human triggers: changes to slope angle and form decrease in toe support increased load on the head interference with drainage

Answer 15

leeward sides of mountain are driver this is because the prevailing winds from the sea move towards the mountain, clouds pass over mountain and the flat land adjacent had descending dry air eg south america

Answer 16

reinforcing buildings snow fences tree planting artificially triggering avalanches preventing access to dangerous slopes

Answer 17

1996 Bangladesh tornado government underestimated disaster Red Cross not permitted with valuable medical supplies Despite widespread injury 1,000 injured in a 200 bed hospital in Tangail

Answer 18

High winds Cyclone or hurricane shelters can be constructed Marked evacuation routes established Along with earnings The removal securing of vulnerable structures

Answer 19

a series of water waves caused by the displacement of a large volume of a body of water, generally an ocean (can be a large lake)

Answer 20

Sea walls can also be constructed but these are not much defence against category 5 hurricanes, warnings given to costa moorings the evacuation of coastal areas

Answer 21

a type of mass movement involving the movement of snow and ice downslope under the influence of gravity

Answer 22

Afforestation Prediction Draining slopes Regarding slopes

Answer 23

low pressure systems up to 600kn in diameter with wind speeds of up to 300km/hr typically 160km/h rostov around a calmer core eye bringing up to 30-50cm of rainfall

Answer 24

new buildings should be designed to be wind and water resistant - building codes communication and utility lines located away from coastal areas and installed underground improvement of building sites; raising ground levels to protect against flood and storm surges improved vegetation cover; helps to reduce the impact of soil erosion and landslides river embankments levees regularly inspected for breaches concrete breakwaters and floodgates protecting ports and costal areas

Answer 25

MUDSLIDES OF SIERRA LEONE AUGUST 2017 Sierra Leone Meterological Office did not issue warnings due to a lack of funding/equipment : GNI of country is $1560 Sierra Leone's Office of National security advised evacuation when satelitte images of the hillside adjacent to the area of the inital slide showed another threat

Answer 26

Deforestation on slopes reduced soil stability and increased soil erosion Unregulated construction; moratorium ignored and the drainage system regularly blocked

Answer 27

LONG TERM unusually wet rainy season - 104mm of rainfall since July 1st - triple the average, leaving the ground saturated, making it heavy, and eventually resulting in a mudflow that killed 1,000 people. SHORT TERM three days of unusually heavy rainfall prior to the event

Answer 28

High risk areas that are therefore without human activity, completely mitigate the hazard posed by mudflows. resettlement programs: the Indian Institute for Human Settlements seeks to reduce the hazard of mass movements in India via resettlement. SOFT ENGINEERING

Answer 29

the triggers themselves are difficult to predict e.g. earthquakes and possibly volcanoes

Answer 30

This could be done by grading, which involves shaping of the rock slope into a more stable configuration, in flattening or leaving ‘benches’ in the slope face. On the other hand, the slope can be excavated or filled to produce a gentler slope. However, this is ineffective in the case of slopes that are not easy to reach, as the mechanical means of achieving slope grading or excavation, requires machinery HARD ENGINEERING

Answer 31

Vegetation reduces the risk of mudflows by removing water through transpiration, the mechanical reinforcement of roots and enhancing soil cohesion increasing shear strength e.g. in Malaysia deforestation plays a major role in mass movement cause so in Pahang, the plant ubi kayu, a species of fast growing tree was planted - after 6 months 75% had sprouted and taken root. Landslides have not occured on these bioengineered plots since vs not managed slopes that have seen undercutting of slope face. This measure is effective and low cost, only $3000 and can be locally constructed, minimal maintenance, attractive as soft engineering can have adverse effects such as reducing bio-diversity and taking up space (which in urban areas, with high population density, is a pertinent issue).

Answer 32

Hydrological triggers: prolonged and heavy rainfall are the easiest to **forecast** but it is difficult to know which slopes are likely to be affected or exactly when it will occur (however some areas are more suceptible e.g. clay areas, steep slopes) Monitoring is also possible with instruments used to measure ground deformation, the expansion of fissures and groundwater pressure the United States Geological Survey has published a series of warning signs that can be observed shortly before a mass movement event: leaning telegraph poles, new cracks or buldges in the ground (volcano) and springs in the ground that had not previously been wet

Answer 33

Italy is more concerned with technological risk e.g. car accidents than antural risks Of the natural risks they are most concerned about earthquakes then floods and volcanic eruptions POR is also deeply influenced by recent landslide events e.g. the people of Calabria percieve landslide risk as very high, but the hazard to life and property as moderate as they have never had a fatal mass movement event

Answer 34

continued rainfall e. g. Sierra Leone (2017) e. g. Mount Ranier, Washington sttae remote areas make resuce/evacuation difficult visitors are unfamiliar to the area/respond slowly soft mud that is difficult to move e.g. Nevado Del Ruiz (1985) up to 4.5 m deep several highways connecting Amero were destroyed by lahars so it took 12 hours for the first survivors to be rescued

Answer 35

mount ranier stratovolcano in washington state 1995 US geological survey automated system detects lahars using a network of small sensors, embedded underground to measure ground vibrations computer base stations analyze signals from field stations upon detection computer sends signal to 24 hour emergency monitoring and notification centres; people are notified via channels of communication e.g. tv, sirens, radio in remote areas people are encouraged to be aware of natural signs: ground rubling roaring sounds similar to jet 10,000 people have between 40 mins and 3 hours to get to saftey

Answer 36

waters of this temperature cause the overlying atmosphere to be unstable enough to sustain convection and thunderstorms

Answer 37

4m of snowfall resulting from a combination of 3 atlantic weather systems - ended up being 170,000 tons freeze thaw conditions created a weak layer on top of the eisting snow pack more snow deposited on top

Answer 38

290km per hour 50m high powder avalanche

Answer 39

31 deaths mostly tourists, overturned cars, powder snow killed people by asphyxiation galtur was marked as green in the hazard map - avalanche safe, with no building reinforcements required 1 in 150 year event wouldnt even reach the village

Answer 40

hazard mapping in all populated reigons of alps red: highly vulnerable no development permitted yellow: moderate developed should be reinforced green: avalanche safe, no reinforcement required reason why impact was so high - Galtur was green with a 1 in 150 chance of an avalanche no monitoring in place (took 60 seconds to hit anyway)

Answer 41

Tropical storms have a diameter of some 500–800 km whereas the destructive path of tornadoes rarely exceed 10 km and may only periodically touch surface tornados leave a footprint of some 50 metres wide and a track of 1–2 km wheras ropical storms may also travel for hundreds of km tropical storms can lasting days, destroying islands and coastal areas – large death toll, widespread property damage. By contrast, tornados last for a few minutes to a couple of hours, causing limited damage – injury or very rare deaths ‘killed tornados’

Answer 42

Mudslides involve the downslope movement of debris with a significant liquid content. They contain at least 50% clay or slit and 30% water Thus, they can travel on lower slope angles than other mass movements 25-45 degrees e.g. debris flows or rock falls It has two main parts: a main scarp – the area of incidence and a toe – the last affected area They have been known to be as deep as 30m They can flow as fast as tens of m per second, carrying debris and smothering villages. For example, the Sierra Leone mudslides of 2017, the saturated mud flow carried mud, large boulders, tree trunks, and other material.

Answer 43

24 hours after a snow storm dumps 30cm of fresh snow

Answer 44

wind moving fast at different altitudes

Answer 45

the wind speed of tornadoes can reach 500 km/h about double that of the most powerful cyclones and the pressure at the heart of a tornado can be 20% below normal ambient pressure.

Answer 46

Hurricane Mitch 1988 rain fillled the creater of the dormant Casita volcano in Nicaragua caused a decrease in shear strength lead to four villages inundated, everything buried in 6m of mud area of 16 by 8 km

Answer 47

Tropical storms develop in a narrow band between 5° and 15° N and S of the equator except in the South Atlantic and eastern Pacific oceans. They do not originate on the equator because of a lack of Coriolis force. They develop in areas where sea temperatures exceed 26 °C and are of sufficient depth to fuel tropical storms which develop from atmospheric disturbance at the meeting of warm and cooler air masses. All tropical storms develop fully where there is no wind shearing. They do not develop on the western coasts of Africa and South America because of the cold offshore currents. Tropical storms track westwards driven by the westerly flowing air streams from the convergence of the NE and SE trades and they veer poleward before dying out.

Answer 48

Tropical storms are much easier to predict than tornados. The strength of wind in a tornado means that conducting investigations into them highly problematic. Scientists can predict tornados using ground and air based radar systems, analysing storm clouds; however, these systems only give warnings a few minutes in advance. By contrast tropical storms can always be seen approaching as they are large and slow moving, meaning evacuation orders can be enabled 3-5 days in advance. For example, in 1998 100,000 people were evacuated from Honduras in advance of Hurricane Mitch. However, Cyclone Nargis was predicted but the Burmese government lacked sufficient infrastructure to do anything about it. Also, the precise track of hurricanes is not always possible to predict, nor is the unexpected strengthening and weakening of the storm as It passes over sea areas of different temperatures.

Answer 49

difficult in terms of the trajectory (within 80km) not possible to predict the intensity at all; strength and weakening as storms pass over hot/cold water this is attributed to the complexity of tropical systems and an incomplete understanding of factors that affect their development

Answer 50

Atlantic/Caribbean satellite imagery and computer modelling predict in April how many hurricanes are expected to make landfall (based on past occurrences and factors e.g. climate – as a %).

Answer 51

achieved via effective, continuous monitoring: information avalible every 6 hours TCWC Once a hurricane has been formed, its path can be predicted 3-5 days in advance, giving people time to evacuate or hurricane-proof their property. This enables small-scale preparedness to take place, the city itself can’t be completely prepared for landfall. For example, hurricane Mitch was predicted 5 days prior, allowing thousands of citizens to be evacuate onto the bay islands. The Indian Metrological agency predicted Cyclone Nargis, but Burmese government did nothing

Answer 52

Local government building flood barriers in the case of storm surges, but these are often very expensive and not always effective. For example, the Fox Point Hurricane Barrier is a 3,000-foot long tidal flood barrier spanning the Providence River in Rhode Island. Alternatively, mangroves can be planted to reduce vulnerability to storm surges by slowing the flow of water. Additionally, communication and utility lines can be located away from areas of water, or located underground. Extreme winds mitigated in an elevated structure on an open foundation, reduces the risk of damage from flooding and storm-driven water In New Orleans area V must have flood insurance to financially protect people from the hazardous impacts of tropical storms

Answer 53

evacuation/fleeing – often late notice as governments are reluctant to enable the release of funds/creation of panic in order to coordinate an evacuation, if the storm will disperse

Answer 54

the intensity of tropical storms can never be predicted, so government predictions, advise and preperation methods are often insufficent - response is the best way of dealing with specific hazardous impacts on an appropriate scale but, it is necessary for a stable political climate and appropriate aid distribution methods - something that even HIC countries struggle with: after Hurricane Katrina saw US gov. criticised for inadequate planning

Answer 55

According to the American Meteorological Society (2014), the majority of people misunderstood that the greatest threat was wind (the damage of this was also underestimate), rather than water.

Answer 56

digging through the rubble to rescue people; sending out search and rescue teams immediately after Hurricane Mitch 1998 armed guards were sent to coordiante rescues and guard businesses that could be looted, 200 people arrested in Honduras

Answer 57

after hurricane mitch US offered $70 million, Roman Catholic church helped to distribute aid across the country. HOWEVER short term response can be hampered by political conditions: Cyclone Nargis in Burma, 2008, the isolationist government only permitted certain flights and denied visa requests Aid was only distributed 2 weeks after the event, making food rations unsuitable

Answer 58

reform of policy towards building design, ensuring homes can withstand storm events; after hurricane mitch 1998 homes were rebuilt and crops replanted over the years the reconstruction efforts acted to lower unemployment rates

Answer 59

. FEMA issue hazard maps yearly in accordance with recent events, weather conditions etc. This is a choropleth map which parallels the Fujita scale (categorising tornados based on damage). Iowa, Kansas and Missouri. Citizens of these areas are advised to build portions of the buildings designed for shelter.

Answer 60

the strength of wind in a tornado means that conducting investigations into them highly problematic; tornado formation not properly understood - forecasting gives few minutes of warnings Scientists can monitor tornados using air based radar systems (5 satellites orbiting 22,000m above earth taking snapshots of cloud formation), analysing storm clouds Also short term, storm spotters report to the national weather service, trained locally on the demands of the area.

Answer 61

government websites with advice such as FEMA Schools/hospitals/malls identify small windowless rooms below ground People in mobile homes or offices advised to go to a secure pre-identified location If evacuation from a building is impossible, then the advice is to take cover under a sturdy table and cover themselves The US has warning sirens/tornado drills

Answer 62

evacuation/fleeing; putting relevant action plans into action Apps such as the American Red Cross notify mobile warnings, allowing people to indicate they are safe through social media.

Answer 63

Simple and inexpensive enhancements to building codes could lead to 30% less damage in Oklahoma opposed by conservative local government with false hazard perception, sceptical about climate change etc.

Answer 64

During the 2013 Mississippi Tornado the response was largely internal. Schools were reopened 4 days later, buses borrowed from neighbouring school districts. 13,000 power outages quickly fixed The red cross and salvation army provided shelter. Following the 1996 Bangladesh tornado, the government massively underestimated the disaster, meaning supplies were not distributed A Government 200-bed hospital in Tangail was overwhelmed with more than 1,000 injured; whilst the Red Cross was not permitted into the country with valuable medical supplies.

Answer 65

improved hazard perception updated hazard mapping reform to building codes

Answer 66

reducing pressure on the slope, controlling slope face processes, e.g. using sheet piles, draining the slope, reducing slope foot processes, e.g. gabions, changing the angle of the slope so it is nearer the stability angle In Hong Kong, a system of ‘mulching’ has been employed, where a protective cover is provided, making it possible for vegetation to grow on the slope, binding the slope surface and securing it in place. Also, reinforced fibre soil systems mixing polyester fibre in sandy soils are capable of resisting tension.

Answer 67

Size: diameter of some 500–800 km; travel for hundreds of km Rotation: anticlockwise in accordance with the Coriolis force wind speeds: highest (category 5 on the saffir-simpson index – above or at 157mph, however some reach speeds of up to 200mph). Hurricane Irma 2017. They move from east to west to impact largely on eastern coastal areas distribution: they start within 8° north and south of the Equator (outside the immediate equatorial area) where sea surface temperatures reach 27°C gain or lose strength in accordance with sea temperature. Areas most at risk are the Caribbean, South East USA and the low lying coasts of Bangladesh. In the northern hemisphere, they occur July – October when sea temperatures are at their highest. rainfall amounts: on average 406mm but can be up to 1,540mm (hurricane harvey 2017) lasts for 6 hours from the storm centre

Answer 68

Vast quantities of rain (up to 125 mm in one hour have been recorded) which usually last for six hours each side of the storm centre. The resultant hazards are extreme flood events and land/mud slides so that the impact can be massive where river levees are breached and slope settlements are destroyed (plenty of examples; Hong Kong, Rio). Winds of over 250 km/hr denote a category five storm on the Safir-Simpson index. The impact is structural damage and a contribution to the development of storm surges by whipping up waves and driving them on shore. Storm surges develop minimally from the low pressure causing a rise in sea level and mainly by the wave generation from high winds being driven on shore. They will be especially hazardous when combined with a period of high tide. The impact is coastal inundation of low lying coastal areas (Bangladesh) and river estuaries (New Orleans). Combined with river floods from high rainfall has a multiplied effect.

Answer 69

hazrd mapping based on onger term on geology and hydrology of an area, but shorter term will depend on recent weather and changes to environment, such as cut and fill new road through mountains, excavations at foot of slopes for new buildings, etc. FEMA produce a hazard map for California, which encompasses the volume of the possible mudsides and the relative hazard of a mudslide – mountainous areas are red. With an 80-100% chance of mudslides within the year.

Answer 70

Even if there is sufficient monitoring, a warning is not always issued. For example, prior to the Sierra Leone mudslides of August 2017, the Meteorological office did not issue a warning due to lack of funding and infrastructure. However, at a later stage after the first mudslide had occurred, an evacuation was enabled.

Answer 71

FEMA. Sign up for your community’s warning system, such as the Emergency Alert System . Know your community’s landslide evacuation plans; Practice driving evacuation routes and identify shelter locations. Gather supplies in case you have to leave immediately or if services are cut off. Keep in mind each person’s specific needs, including medication. Plant ground cover and build walls to direct the flow around buildings.

Answer 72

Only once an event has happened the specific needs of the affected area can be addressed planning and preparation prior to an event are inevitably much more generalized and can’t necessarily anticipate the scale or intensity of the hazard

Answer 73

Red Cross and government donated 15 vehicles to isolated areas. UN sent forensic officers and specialized rescue units, dogs. WTP provided rations for 7,500 people. Workers in regent constructed 4x 10,0000L water harvesting systems as there was a fear cholera would break out. The UK provided storage tanks, purification tablets and hygiene advice.

Answer 74

government under international and domestic pressure to reform building policy to protect the poor who are inevitably hurt by their ability to only afford housing on unstable and marginal land The IFRC approved 4.6 million Swiss Franks to be distributed through Sierra Leone agencies over 10 months following the disaster – helping to rebuild and provide temporary accommodation.

Answer 75

Tend to occur due to heavy rainfall, oversaturating the slope, increasing the weight of the soil. Shear stress becomes greater than shear strength and a mudslide occurs. For example the 2017 Sierra Leone mudslides were triggered by an unusually rainy season (triple the regions seasonal average for July). This high level of rain was not appropriately handled in the infrastructure of the area, with blocked drains preventing infiltration. This was exacerbated by the deforestation on the slope in order to meet the growing demand for homes (increased population pressure). Deforestation reduces the anchoring effect of vegetation, increasing susceptibility to soil erosion. These buildings additionally increased the weight on the slope, increasing shear stress and so the vulnerability to a trigger. ALSO: Geology (rock types and structures) e.g. permeable strata overlying impermeable, faults or joints allowing ingress of water. Removal of the foot slope, i.e. allow a stable slope to develop; undermining the cliff

Answer 76

Wet snow avalanches are the most powerful and generate the most hazards; They occur in spring with partial snow melt. Powder avalanches can cause asphyxiation as occurred following the Galtur avalanches (31 deaths). Powerful shockwaves precede it. The cold weather associated with heavy snowfall can create additional suffering - suffer hypothermia and frost-bite before help arrives. If triggered by earthquakes they are the most hazardous – as a secondary impact. Animals caught off-guard may be swept to their deaths; hoofed mammals such as mountain sheep are particularly vulnerable. Blockages of roads, mountain passes and streams and damage to electric and communication lines. Blockage of streams and later release of the impounded water create flash floods with disastrous effects. Most hazardous in the location of settlements.

Answer 77

Snow avalanches occur mostly on slopes between 25 and 40 degrees Slab avalanches tend to occur in spring when partial melt occurs at depth, due to a sudden rise in temperature. This causes water to percolate through the snowpack, leading to instability (reduction in shear stress) at a well-defined failure surface. A plane of weakness emerges in the upper layers of snow. Because of this weakness, human activity can then trigger an avalanche. For example, the vibrations from the movement of a snowmobile or earth tremors due to movement in the earth’s crust. Snowmobiling is the leading cause of avalanche fatalities in Idaho. Mass overcomes friction and a resultant avalanche occurs.

Answer 78

Powder avalanches can occur at any time following a heavy snowfall over a partially frozen snow surface (however, tend to occur in winter seasons – Northern Hemisphere November-Februrary, Southern Hemisphere June-August). Avalanches are most common after a storm that deposits 30cm of fresh snow. the Galtur avalanche 1999 was triggered by 4m of snow from 3 different weather systems. This most often occurs on a smooth surface e.g. after rain – without the cohesion with the snow layer underneath, it cant settle. Freeze thaw conditions created a weak layer on top of the existing snow pack that prompted destabilisation This then reaches a critical point where mass is overcome by friction and an avalanches results.

Atmosphere & Mass movement Flashcards

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