Hazardous Environments

Question 1

Body Waves

Answer 1

Bodywaves: waves within the earth’s interior
P waves: travel by compression and expansion
S waves: travel with a side to side motion

Question 2

Surface Waves:

Answer 2

Surface waves: when body waves reach the surface:
Long waves: sideways movement
Rayleigh waves: up and down movement - most hazardous.

Question 3

Soil liquefaction

Answer 3

loose sand and silt that is saturated with water can behave like a liquid when shaken. Pore water pressure increases so sand grains lose contact with each other = soil loses ability to support structures. = quickly solidifies hence structures trapped in the ground.

E.g Christchurch Earthquake aftershock of 7.1 in 2011 caused widespread liquefaction. Leading to $16bn in damage.

Question 4

What and causes of Tohoku earthquake

Answer 4

11 March 2011 earthquake and Tsunami, Japan.
Magnitude 9, lasted 6 minutes.
Tsunami waves, on average 3-6m.

Causes:
Pacific plate subducting beneath the Eurasian plate. Focus 32 km in NW Pacific ocean. Epicentre 70 km east of Tohoku. Earthquake caused an upthrust of 8m along 180 km seabed.

Question 5

Impacts of Tohku earthquake

Answer 5

Primary:
16,000 deaths in Japan. Estimated 92% died from drowning, 4% crushed in earthquake. 127,000 buildings destroyed.

Secondary:
Fukushima nuclear incident. 4.4 million households without electricity, 1mn households without access to water. 25 million tonnes of debris in coastal areas.
World bank estimated economic cost = US$235bn.

Question 6

Management before Tohuko earthquake

Answer 6

Many large foreshocks record: e.g first major fore shock = 7.2 magnitude on 9th march.

Recurrence interval for tsunamis on sendai plain estimates a 800 - 1100 year recurrence interval for large tsunamigenic earthquakes. = In 2007, the probability of an earthquake with a magnitude of 8.1–8.3 was estimated as 99% within the following 30 years

One minute before the earthquake was felt in Tokyo, the Earthquake Early Warning system, which includes more than 1,000 seismometers in Japan, sent out warnings of impending strong shaking to millions = saved lives as high speed trains and factory lines stopped, earthquake drills enacted.

Earthquake proof design; e.g Mori Tower, Tokyo. - 54 stories but has 192 of fluid-filled shock absorbers filled oil, which acts as a counter balance to swaying.

Tsunami wall line 40% of Japan’s coast - but these were overtopped. E.g at miyako 4m in height. Replaced by 12.5m

Question 7

management after Tohoku earthquake

Answer 7

Residents within 20km of Fukushima were evacuated after the failing of the cooling system = radiation levels inside 1000x normal =

State of Emergency Declared.

Japanese red cross reporting $1bn in donations, 116 countries and 28 NGOs offered assistance.

Question 8

What and causes of haiti earthquake

Answer 8

12 January 2010 Haiti Earthquake. Magnitude 7.

Focus 13 km. Epicentre 25 km west of Port au Prince. Occurred along a conservative plate boundary. Caribbean plate is moving 20mm per year faster than the North American Plate. g

Question 9

impacts of haiti earthquake

Answer 9

160,000 deaths. 250,000 buildings severely damaged/destroyed. (there are no building codes in haiti)

Question 10

management after haiti earthquake

Answer 10

More than 20 countries sent military personnel to assist with relief and rescue. But efforts were restricted due to congestion and blocked roads. 23 NGOs raised US$1bn for relief. Six Months after the quake, 98% of rubble remained uncleared.

Question 11

Icelandic eruption

Answer 11

Icelandic eruption: persistent fissure eruption. Large quantities of basaltic lava build up vast horizontal plains.

Question 12

hawaiian Erruption

Answer 12

Hawaiian Eruption: runny basaltic lava travels down the sides of the volcano in lava flows. gases escape easily. Occasional pyroclastic activity but small.

Question 13

Strombolian eruption

Answer 13

Strombolian Eruption: frequent gas explosions which blast fragments of runny lava into the air to form cones. Very explosive eruptions with large quantities of pyroclastic rock thrown out. Common to have white steam cloud from crater.

Question 14

Vulcanian eruption

Answer 14

Vulcanian eruption: violent gas explosions blast out plugs of sticky lava. Fragments build up into cones of ash and pumice. Occur when there is very viscous lava which solidifies rapidly. Often large quantities of volcanic ash.

Question 15

Vesuvian eruption

Answer 15

vesuvian eruptions: very powerful blasts of gas pushing ash clouds high into the sky. lava flows and ash clouds.

Question 16

Plinian eruption

Answer 16

Plinian eruption: gas rushes up through sticky lava and blasts ash and fragments into the sky in the largest and most violent eruption. Immense clouds of gas and volcanic debris kms thick.

Question 17

Pyroclastic flows

Answer 17

flow of hot gas, ash and larger volcanic matter. Reaches up to 700C and 150km per hour.

Question 18

Mount St Helens What and Causes

Answer 18

18th May 1980 VEI 5 eruption at Mount St Helens, Washington.

Volcanoes formed due to the subduction of the Juan da Fuca plate beneath the North American Plate forming the Cascade volcanic chain.
A 5 magnitude earthquake on May 18, 1980, caused the entire weakened north face to slide away, creating the largest landslide ever recorded. This allowed the partly molten, high-pressure gas- and steam-rich rock in the volcano to suddenly explode northwards.

Question 19

Mount st Helens impacts

Answer 19

primary:
Eruption column rose 80,000 feet in the air = deposited ash in 11 states, 65% silicon dioxide.
Snow, ice and glaciers on volcano melted = lahars that travelled 80 km SW and affected 3 out of 4 major drainage systems.
Pyroclastic flows formed travelled at max speed of 1,080km/hour. Destroyed 600km2 of forest but extreme heat caused tree deaths beyond this zone.
57 deaths from asphyxiation some fro burns. Due to pyroclastic flow that was 360 C when it hit people and filled with gas and debris.
200 homes, 47 bridges, 15 miles of railways, 185 miles of roads destroyed.

Secondary:
Ash deposited in 11 states = fall in visibility= closure of interstate 90 for 1 week. 1000 flights cancelled.
$3bn dollars of damage.

Question 20

Mount St Helens management

Answer 20

before:
123 years of dormancy. Forecasting before event due to two month series of earthquakes and steam venting episodes . 8 earthquakes per day the week before the eruption. The mountain swelled with magma and bulged outwards at a rate of 1.5m per day.
Washington state Governor placed a 5 mile red zone around the summit. BUT the blast extended to 4x the exclusion zone/

after:
removing the ash from one town took 10 weeks and cost £1million.

Question 21

Fall example

Answer 21

E.g Yosemite National Park January 2017, Rockfall with total volume of this slide was about 20,000 cubic meters

Question 22

Slides example

Answer 22

E.g Southern Leyte Mudslide, Philippines 2006. 1126 deaths

Question 23

Heave example

Answer 23

E.g terracettes visible at manger, near uffington white horse.

Question 24

Avalanche example

Answer 24

E.g Huascaran avalanche, peru may 1970: 80 million cubic feet of ice, mud and rock travelled nearly 11 miles, burying the towns of Yungay and Ranrahirca in up to 300 feet of rock and debris.

Question 25

What are hurricanes?

Answer 25

A severe, rotating tropical storm with heavy rains and cyclonic winds exceeding 74 miles per hour. An area of low pressure (as low as 880mb) over tropical or subtropical water where trade winds converge.
Surface winds of 74 mph. Anti clockwise rotation in N Hemisphere.

Question 26

Where do hurricanes occur

Answer 26

Over oceans (5-20 N or S of the equator), although some make landfall.
They are NOT on the equator;
They tend do occur on east coasts.
They are NOT found in South America.

Question 27

how do hurricanes form?

Answer 27

Warm oceans (at least 26C) between the tropics, heats the air above it = expands = less dense = rapidly rises = extreme low pressure area at surface (880mb)
Also warm oceans = evaporation = condensation of water vapour when cools = latent heat released which drives the storm as air rises further and more rapidly = creating lower pressure at surface
Unstable conditions; atmosphere cools quickly with height that a parcel of rising air is warmer than air at the same height so continues to rise.
There is low wind shear; winds in the upper troposphere must no be too strong to remove the top of the storm system.
Spiralling system due to coriolis force.

Question 28

Hurricane Irma what?

Answer 28

Hurricane. Formed 30 August 2017 near Cape Verde Islands. Made landfall on 6th September in Barbuda,
(282kph wind speeds) continued north as a Cat 5 hurricane. Reached Florida on 10th September as Cat 4 (209kph) Dissipated 13 September 2017. Diameter of 644km.

Question 29

hurricane irma impacts of USA

Answer 29

Primary:
92 deaths in the USA. 50% from drowning.Greatest impact in florida.
Peaks of 550mm rain in Florida.

Secondary:
Damage in the USA was estimated at $50billion. 73% of Florida was left without electricity.
Havy rain and storm surges caused 32 rivers to overflow.

Question 30

Hurricane irma management USA

Answer 30

Before:
In Florida, in 2002, legislature passed a statewide building code that requires buildings to at least be able to withstand winds of up to 111 mph. E.g with multiple construction tiw from the walls to floor, and reinforced windows with impact glass.
10-mile-long seawall in Galveston, Texas

after:

More than 40,000 federal personnel, including 2,650 FEMA staff, were in place by September 14. In addition, FEMA had transferred 6.6 million meals and 4.7 million liters of water to states in the Southeast after Irma as of the 14th

Question 31

hurricane irma impacts of caribbean

Answer 31

42 Deaths in Caribbean islands. (10 in cuba, 11 in French West Indies)
Flattened 95% of buildings in barbuda. Island uninhabitable to 1600 residents. Economic loss for Antigua and Barbuda estimated at $120mn.
Waves of 9m reached Puerto Rico. 1mn residents lost power.

Question 32

hurricane irma management in caribbean

Answer 32

Hurricane Warnings were issued for the northern Leeward Islands, Puerto Rico, and parts of Hispaniola on September 5.
In Turks and Caicos island Officials spread warnings to residents in English, Creole, and Spanish via social media, radio, SMS text, and WhatsApp.

11, 200 people were evacuated from the dominican republic.

Preparation in Haiti was poor, with no mandatory evacuation orders.

In the Bahamas the government secured sport facilities to use as shelters, evacualted 1,600 people by air form southern islands, cut power supply.

Question 33

What are tornadoes, where do they form.

Answer 33

What are Tornadoes?
A rapidly rotating column of air between the base of a cumulonimbus cloud and the earth’s surface.
Typically 20-100m wide, track of 1 mile, lasting for no more than 20 minutes.

Where?
Overland. 90% in the USA in Tornado Alley. (Where cold air form the rocky mountains meets warm air form the gulf of Mexico in Central and Southern States).BUT rare; 1200 in USA a year.

Question 34

Indiana/kentuckey tornado

Answer 34

indiana/kentucky tornado november 2005 = killed 16 people, injured 200, 1.2km wide and track of 32km. Emergency sirens sounded as warnings but most did not responds as tornado occured at night. But can also occur in other areas

Question 35

Birmigham tornado

Answer 35

E.g birmingham in July 2005 = winds of 209 km/h tore through small heath district, 1000 buildings damaged, 12 injured. Government granted emergency aid to birmingham. Leaflets on practical advice were issued after event.

Question 36

How do tornaodoes form

Answer 36

Extreme heat on the ground causes warm, moist air to rise in updraughts, as it expands and becomes less dense.
This meets cold dry air, creating unstable conditions and forming cumulonimbus clouds.
The upward movement of air is rapid, creating low pressure at the surface = winds are drawn in from different directions causing rotation.
Wind speed increases with height, causing higher, faster moving air to roll over slower moving air below.
This creates a horizontal spinning column of air, that is known as a vortex. This turns vertical due to horizontal updraughts of warm rising air.
This is known as a supercell, as a thunderstorm has a persistent rotating updraught at its core.
Downdraughts of cooler air, due to xxxxx within the supercell force the column down. If the column touches the earth’s surface it is classified as a tornado.

Question 37

Tornaodes hazardous impact facts

Answer 37

On average tornadoes kill 60 people per year.

the strongest winds on the face of the planet. On average 70 mph, but reaching 300 mph.

BUT tornadoes tend to cause less than 1/10th of the economic damage of hurricanes per year, because hurricanes affect a much large area for a longer time period.