hazardous earth

Question 1

discontinuity separating crust and mantle

Answer 1

moho discontinuity

Question 2

asthenosphere depth

Answer 2

100-300km

Question 3

thickness of different crusts

Answer 3

continental 25km, oceanic 5-10km

Question 4

geological evidence of continental drift

Answer 4

continental fit, geological matching sequences, mountain ranges

Question 5

biological evidence of continental drift

Answer 5

fossils found in separate continents, e.g. mesosaurus, glossopteris

Question 6

climatological evidence for continental drift

Answer 6

oil and coal in south Wales, not on equator, glacial striations in South America and India,

Question 7

evidence of sea floor spreading

Answer 7

paleomagnetism, older rocks further from ridge, GPS, apparent polar wandering

Question 8

oceanic-oceanic boundaries

Answer 8

older more dense plate subducts, dehydration causes partial melting of the mantle wedge in the plate above, magma rises to the surface and forms island arcs/volcano chains

Question 9

continental-continental boundaries

Answer 9

little/no subduction as they have similar density, African and eurasian plates created alps over 40million years

Question 10

conservative plate margins

Answer 10

slide past each other, frictional resistance caused pressure and earthquakes.

Question 11

strato volcano eruptions

Answer 11

high silica content (andesitic/rhyolitic) viscous lava, gases become trapped building pressure, explosively erupts

Question 12

effusive eruptions

Answer 12

low silica content, basaltic, low gas content due to low viscosity, gases can escape, magma rises easily and lava flows result.

Question 13

hotspots

Answer 13

fixed area of intense volcanic activity from a rising magma plume which reaches the earth’s surface.

Question 14

volcanoes in hawaii

Answer 14

Mauna Loa and Mauna Kea, 4000m above sea level 9000m from sea floor

Question 15

hotspot with potential

Answer 15

loihi, 970m below sea level

Question 16

mountain created from rift valley in Africa

Answer 16

mount kilimanjaro

Question 17

explosive hotspot in tenerife

Answer 17

el teide

Question 18

what classes a super volcano and give examples

Answer 18

erupts more than 1000km3 of material, Yellowstone, 27,000 years ago Taupo NZ

Question 19

way to measure volcanoes

Answer 19

VEI, 1-8, each increase near to 10 fold increase in explosively.

Question 20

lava flows impacts

Answer 20

basic lava free flowing, Hawaii 2015 ran for 20km, acidic lavas do not flow easily. lava can destroy infrastructure and crops however rarely cause injuries and casualties.

Question 21

pyroclastic flows

Answer 21

combination of very hot gases, 500 degrees or more, ash and rock fragments, travel at 100km/h, follow contours of the ground and destroy everything in their paths.

Question 22

tephra

Answer 22

described any material ejected from a volcano, ranges from ash to lava bombs which are greater than 6cm across. tephra can bury farmland in ash and destroy crops. may also enter stratosphere, disrupting travel, e.g. E-15 2010 cancelled 100,000 flights

Question 23

gases during eruptions

Answer 23

eruptions also release gases such as CO, CO2 and SO2, can be toxic and also lead to acid rain, damaging crops and polluting water.

Question 24

lahars

Answer 24

mud flows resulting from snow and ice melting on a volcano during an eruption. rock fragments are mixed together with ash and soil and can travel at 50km/h. example is Nevado del Ruiz (1984) killed 23,000.

Question 25

floods from volcano

Answer 25

floods may also result, for example if a glacier is on top of volcano, jokhulhlaup.

Question 26

tsunamis from volcanoes

Answer 26

island volcano eruptions can displace lots of water, causing tsunamis at speeds of up to 600km/h. e.g. Krakatoa 1883, 36,000 killed from tsunamis.

Question 27

climate change resulting from volcanoes

Answer 27

toba in indonesia, 70-77,000 years ago, reduced global temperatures as ash blocked sunlight

Question 28

lake ncos

Answer 28

in volcanic crater, 1986 1700 killed

Question 29

p waves

Answer 29

fast travelling, low frequency, vibrate in direction of travel

Question 30

S waves

Answer 30

move at half the speed of p waves, high frequency, vibrate perpendicular to direction of travel, cannot pass through liquids

Question 31

l waves

Answer 31

slowest type of wave, some move vertically while others move at high angle, only travel through outer crust

Question 32

shallow focus

Answer 32

down to 70km, results form fracturing of rocks due to stress in crust.

Question 33

deep focus

Answer 33

70-700km, increased depths, increased pressure and temperature, minerals change type and volume and dehydration of water.

Question 34

different earthquake measurements

Answer 34

Richter 1-10, merchalli 1-12 , moment magnitude 1-10

Question 35

2008 sichuan magnitude

Answer 35

8.0 MW

Question 36

2015 Nepal magnitude

Answer 36

7.0 MW

Question 37

rift valleys evidence of earthquakes

Answer 37

fault scarps or scarpments, mark locations of faults caused by tension and compression within crust

Question 38

general stats about earthquakes globally

Answer 38

every year around 100, between 2000 and 2015 800-900,000 people died from earthquakes

Question 39

ground shaking impacts

Answer 39

locations closer to epicentre with unconsolidated rock layers and high water content will have more ground shaking. e.g. Kobe 1995. Tokohu earthquake of 2011 lasted 5 minutes, damage can be roads, railways, buildings, sewers.

Question 40

liquefaction

Answer 40

when are of fine grained sands and high water content, vibrations cause materials to behave like liquids, materials lose strength and structures tilt and sink. Kobe earthquake 20 berths were destroyed.

Question 41

land slides and avalanches from earthquakes

Answer 41

slope failure from ground shaking, tremor trigger landslides, Nepal 2015, these can block transport routes in mountainous regions where accessibility is already difficult, may also block rivers creating natural dams and floods downstream, e.g. Sichuan 2008. may also displace water and weaken dams of reservoirs, such as northern Italy 1963, 3000 people killed by 100m wave

Question 42

tsunamis from earthquakes

Answer 42

underwater earthquakes displace water, causing the sea bed to rise vertically. Aceh province estimated to 1000 tonnes of water per meter of shoreline. underwater landslides, 1998 2200 in Papua New Guinea killed.

Question 43

dormant volcano

Answer 43

hasn't erupted for 10,000 years, e.g. Mt St Helens until 1980

Question 44

Japan volcano case study

Answer 44

110 volcanoes, e.g. Mount Fuji. 1200 eruptions in past 2000 years. Mount ontake, stratovolcano 200km west of Tokyo, 3000m and erupted unexpectedly in 2014, killing 63.

Question 45

indonesia volcano case study

Answer 45

80 active volcanoes, 3/4 live within 100km of a volcano, Krakatoa 1883, merapi 3000m, 2010, vei 4, pyroclastic flows 4km, lava bombs 4km, lahars triggered due to rainy season, closure of airport, SO2 led to acid rain. 367 killed, 410,000 became refugees. 130 millionM3 of material from ash and pyroclastic flows destroyed crops and infrastructure

Question 46

java volcanic soils

Answer 46

fertile soils allow for 3 crops of rice a year

Question 47

Japan earthquake

Answer 47

tohoku 2011, 9.0 MW, 70km offshore, large tsunamis up to 40.5m in places, travelled 10km inland, 16,000 killed, 100,000 children affected, 2,000 orphaned, cost estimated at higher than 200bn, 45,700 buildings, 230,000 vehicles, 10% of fishing ports,

Question 48

Haiti earthquake

Answer 48

2010 earthquake 7.0MW, focus 12km, 316,000 deaths, 300,000 houses, 30,000 commercial buildings, 1.5 million displaced, over 30,000 still in camps in 2020

Question 49

Haiti HDI change 2009-2020

Answer 49

149th in 2009, 169th in 2020