tectoinic landscapes Flashcards
(25 cards)
world distribution of volcanos and Earthquakes
earthquakes
coastal areas and plate boundaries
(destructive & conservative)
-south American & nazca = destructive
-pacific & Philippine & indo-Australian
volcanos constructive and destructive over hotspots e.g. Hawaiian = 3,700mile chain -indo Australian and Philippine -bottom of Arabian
theory of plate tectonics
the world was once one piece of land it is divided into plates continents move because they are on plates evidence = puzzle constructive, destructive, conservative
why earthquakes occur where they do
coastal areas and plate boundaries
- plates rub which causes friction
- pressure builds on uneven edges
- sudden jolts
- earthquake happens
why volcanos occur where they do
occurs at destructive, conservative & where hot spots are
- C02 is trapped when 1 goes under
- it rises in convection current it burst up
- makes a hole where lava come through
what are hotspots
places within the mantel
heat rises as a thermal
rocks melt
generates lava.
how are volcanos created
high heat and low preasure
base of lithosphere
magma rise though cracks
erupts
usually at hotspots where c02 has burst to make cracks
example of hotspot
Hawaiian
- 3,700mile volcanos chain over pacific ocean
- some volcanos = 30,000 ft over sea floor
- more than 80 large volcanos
- runs 200miles
- passages feed volcanos with lava
features of convergent (destructive)
pushed together = mountainous ridges created himalayers or 1 is pushed under volcanos and earthquakes form Nazca and south American
types of convergent (destructive)
oceanic & oceanic:
(eastern pacific)
-no fold mountains
-volcanos produce islands when lava cools
-pacific is sub ducting below the Philippines
continental and oceanic (west coast of south America) -oceanic = more dense -continental goes under oceanic -loss of land -Nazca under south American
continental and continental (himalayers) -fold mountain ranges -no volcano -eurasion and indo Australian (caused 2005 Pakistan earthquake)
features of divergent (constructive)
- moving away
- volcanos
- no earthquakes
- Nazca and pacific
features of conservative
- moving past eachother
- no volcanos
- earthquake from release of pressure
- san adreas fault (san fran) 1989 earthquake
- pacific and north-american
characteristics of focus / epicentre
focus = where the earthquake occurs
-it may be many km deep
epicentre = point on the earth’s surface above the focus
-most damage occurs here
richter scale
measures strength (magnitude)
logarithmic - each number is 10x the previous
never ending
few are larger than 9
greatest was 9.5 chile in 1960
seismometers
measure ground vibraions
mercalli scale
measures the intensity of the damage
by observing the ground
12 point scale
why people live in areas of volcanic activity
- renewable geothermal energy
- tourism
- hot springs and baths e.g. Iceland
- mining (cool lava = gold,silver&diamonds)
- agriculture (good soil) = sulphur and nitrogen
negative effects of volcanos
human
- homes, land, valuables lost
- death and injury
- comminicaton
- destruction of farms
- travel
environmental
- habbits and animals lost
- crops dead from lava and no light from ash
- mass pollution
- temp drop = very cold
example of erupting volcano and why
Montserrat, Caribbean island
10x7miles and 25 miles of coastline
1995&1997 eruptions of soufriere
pyroclastic flows of 600 degrees, 70/80 mph
destructive plate boundary (Atlantic plate)
why:
- destructive plate = atlantic under Caribbean
- convection currents pull atlanic into mantle where friction and heat melts the rock
- ^^ increases pressure and causes earthquakes
- hot magma rises to make volcano
effects of case study erupting
human:
- communication and travel gone
- 23 died
- half population evacuated (9000 people by 2000)
- water pollution
economic:
- evacuation = less money being made
- Plymouth (capital city) is a ghost town
- airport close = no tourism
- valuables lost and cost to relocate
environmental
- 2/3 island covered in ash
- plants die from lava, less light and heat
- fire ignited volcanic gasses
- ash contaminated river
responses to case study erupting
- £41 million in aid by British government
- money given in aid to individuals who migrated
- riots because locals didn’t get enough help
- Montserrat observatory now monitors the volcano
- risk assessments to predict future eruptions
predicting and forcasting earthquakes
animals behaviours
minor tremours recorded
electrical signals
patterns and trends e.g. san fran = 1/140years
gas monitors (sulphur dioxide = volcanos)
preventing effects before eruption
education: -earthquake and evacuation drills by government -Japan teaches safety in schools ways to plan ahead -check for domestic hazards -identify safe place -educate youself -supplies on hand -emergency communication plans -help community
building earth quake proof
Tamaki building aukland
earthquake proof
- 2 wings of main building split by a joint
- 10cm joints on all levels of building
- controls movement
- reduces seismic wave impact
san fran international airport
earthquake proof
- giant ball bearing
- 267 collums support 1.5 m2 steel ball
- ball rests on concrete “floating”
- ball moves 50cm in any direction
