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Question 1

what causes volcanoes

Answer 1

o Magma is underneath the earth’s crust
o When the tectonic plates pull apart (diverging) or one is pushed under another (subduction) magma comes up
o The magma can either explode out of the space or flow out
o Magma that has erupted is called lava

Question 2

What are the three types of volcanoes

Answer 2

Cinder cone
stratovolcanoes
Shield volcanoes

Question 3

What is a cinder cone

Answer 3

o Also called scoria cones and are most common
o Symmetrical and cone shaped we usually think of
o May occur as single or secondary (parasitic)
o Airborne fragments of lava (tephra) are ejected from single vent
o Cinders fall and these volcanoes are very small, building up over years

Question 4

Stratovolcanoes

Answer 4

o Called composite because built of layers of alternative lava flow, ash and blocks of un melted stone
o Larger than cinder cones
o Result from tube like system from magma below surface
o Concave sides and small crater
o Erupt with great violence, when magma reaches conduits gas released and explodes
o Can blow out sides as well as top

Question 5

shield volcanoes

Answer 5

o Huge, gently sloping with very thin lava spreading out from central vent
o Wide bases with a flatter summit
o Eruptions are not very explosive, more like liquid flowing over top of container

o Most active and constantly monitored

Question 6

What causes earthquakes?

Answer 6

o Tectonic plates float upon magma and is constantly moving against each other
o When the friction is violent enough it causes seismic waves
o These ripple through the ground rattling everything standing on it

Question 7

Where are the most violent earthquakes formed?

Answer 7

o Through subduction zones
o This is when one tectonic plate moves under another
o While one goes down the other goes up rocking the surface violently
o When happens underwater it causes a tsunami

Question 8

How is the magnitude of an earthquake measured?

Answer 8

o Through the Richter scale
o Runs from 0 to 10 (10 being the strongest)
o Everyone one up means 10 times more ground motion

Question 9

What are some ways that humans can prepare for earthquakes?

Answer 9

o Stronger buildings with more flexible structures and lighter roofs
o Collecting data to project the power of future earthquakes
o Also use data to find when and where they will strike

Question 10

How are earthquakes monitored?

Answer 10

o Through seismograms
o With S waves and P waves
o Determine the difference between the start of the p wave and the start of the s wave
o Use the difference to determine the distance from the epicentre

Question 11

What is a seismogram and what are the most significant parts on it?

Answer 11

o A seismogram is the graph that measures how big the earthquake is

o The most important parts are the P waves and the S waves
o By finding out the interval time between them we are able to then go on to determine a location and figure out how large it was

Question 12

How is it used to locate the epicentre of an earthquake?

Answer 12

o After subtracting the start of the P wave time from the start of the S wave time you find the time between them
o On a graph you locate this point and connect the line down to the correct distance
o You then use this distance on a map and find the location of the epicentre

Question 13

Summarise the different types of seismic waves and how they are felt at the earth’s surface

Answer 13

o P waves: P waves are primary waves. They are faster than S waves. They are made up of compression waves, also known as push pull waves. They push against each other causing a parallel straight motion
o S waves: They are transverse waves and come after p waves. Transverse means they vibrate up and down, perpendicular to the motion they travel in. Particles move up and down and the wave moves forward

Question 14

What do engineers need to consider when designing a building that can withstand a volcanic eruption?

Answer 14

o Building interiors: Ash contamination may lead to risk of health hazards
o Abrasive damage to roofing, cladding and floor materials
o Loss of essential services to the building
o Building support systems: things such as heating and air conditioner
o Building envelope: things such as gutters, metal roofs and recently applied paint
o Structural damage to excessive ash loading: thick ash deposits may cause collapsing

Question 15

What design features make a building more resistant to volcanic eruptions?

Answer 15

o Evacuation routes: Locations need to be selected based on practicality to evacuate the area. Windows should face the volcano so they can see if it erupts
o Lateral Support: Flat roofs instead of sloped roofs due to scientific research
o Covered outside areas: Ash can still blow sideways so they need to be careful of things like balconies, car ports and decks. These will need additional support

Question 16

what is Steep slope roof:

Answer 16

o It is found that metal roofs with 15o slopes retain most of the ash that fall on them. Roofs with a 25o shed some of the ash. Roofs with a 45o shed most of the ash. As long as they are well braced, steeply sloped roofs are preferred.

Question 17

what is Triple roof support:

Answer 17

o Snow weighs 50-300 kg/m3, but ash is 400-700 kg/m3, or more than double that if saturated with rain. This means more than triple the weight of the thickest snow on the roof, and there is no telling how much ash will get dumped on the roof.

Question 18

what is Smooth roof material:

Answer 18

o As with snow, smooth roof materials will slide the ash away and avoid the complicated assembly that holds additional ash.

Question 19

what does it mean when we talk about Concrete structure:

Answer 19

o Researchers of the Mount Pinatubo eruption found that timber framed buildings were much more likely to fail, and that reinforced concrete fared the best. Concrete is suitable against the wind and earthquakes associated with volcanic eruptions.

Question 20

What do engineers need to consider when designing an earthquake resistant building?

Answer 20

o Must design support elements of shorter buildings to withstand greater forces
o The materials determine its strength and most importantly flexibility
o Building with concrete is better than wood and steel/ what materials will benefit in the situation more
o Must be reinforced to stand high winds and can absorb the energy of waves
o Most importantly the truss which is the base of the building/supporting the building horizontally and vertically

Question 21

What design features make a building more earthquake resistant?

Answer 21

o Base isolators
o For tall buildings, importantly is the truss
o The material it’s made from, specifically concrete instead of timber or something similar
o Designing structures to absorb the energy of the waves
o Must be reinforced to withstand strong waves

Question 22

What is Diaphragms:

Answer 22

o The diaphragm holds the building together so when pressure is placed by earthquakes, it stays whole. It is a concrete slab on the top of the building connected
o If a building does not have a diaphragm it is often different slabs meaning the walls could potentially collapse down during earthquakes

Question 23

what is Cross Bracing:

Answer 23

o This is a way to support buildings in which diagonal beams intersect. It is important because it helps keep a structure standing.
o It is usually when 2 diagonal supports are placed in a diagonal x shape

Question 24

what is Base Isolation:

Answer 24

o One of the most powerful ways to keep structure to a building during an earthquake
o It is when the building is built away from ground resting on flexible bearings or pads known as base isolators, it will only move a little or not at all during an earthquake.

Question 25

what is Dampers:

Answer 25

o A device mounted in structures to reduce the amplitude of mechanical vibrations.
o This prevents discomfort, damage and structure failure during an earthquake

Question 26

what is Shear Walls:

Answer 26

o Walls placed on the ground floor covering openings from the roof down to the floor, so it helps hold up the building
o It helps keep it ridged and so therefore perfectly intact during earthquakes.

Question 27

what is Lifeline engineering:

Answer 27

o 6 levels: electrical power, gas and liquid fuels, telecommunications, transportation, waste disposal and water supply
o This focuses on what to do after an earthquake and how to provide secure and safe resources in the time of need