Tectonics

Question 1

7 major plates

Answer 1

• The Pacific
• The Eurasian.
• The African
• The American
• The Indo Australian
• The Nazca Plate
• The Antarctic plate.

Question 2

Active volcano

Answer 2

– if they have erupted recently

Question 3

Dormant volcano

Answer 3

resting – have not erupted recently

Question 4

Extinct volcano

Answer 4

will not erupt again

Question 5

Shield volcanoes

Answer 5

• Shield volcanoes have very runny lava (non-viscous); because of this they do not have
  an ‘explosive’ eruption.
• Lava spreads quickly across the landscape.
• With each eruption a new layer of rock is built on the previous one.
• Gradually a wide dome of rock is built up.

8
* It is called a shield volcano because it looks like a curved shield lying on the ground (or
an upside down dinner plate).
* The slopes of a shield volcano are very gentle.
* The Hawaiian islands are a chain of shield volcanoes

Question 6

Composite/strato volcanoes

Answer 6

• Composite volcanoes are the most common type of volcano.
• When you think of a volcano you are probably picturing the classic cone shape of the
  composite volcano.
• They are formed by hardened layers of lava and ash from successive eruptions.
• The lava is viscous (therefore thicker than with shield volcanos) and it cools and hardens
  before spreading very far, therefore the volcanoes are steep sided.
• The eruptions tend to be very violent, capable of producing deadly pyroclastic flows.
• Mount Vesuvius in Italy is an example of a Composite Volcano.

Question 7

Volcanic Eruption Case Study Eyjafjallajökull Volcanic Eruption (2010)

Answer 7

Eyjafjallajökull is a moderately active volcano that had not erupted for 180 years before it came
to life in 2010.
There has been 18 years of volcanic unrest before the 2010 eruption. This activity had been
carefully monitored by satellite radar, GPS receivers and seismic monitoring.
Rather than one magma chamber filling up before the eruption, scientists believe two separate
sources of magma had been accumulating. The volcano erupted through the coming together of
these two types of magma. One type of magma was basalt and the other was silica-rich andesite.

On March 20 2010, Eyjafjallajökull began spewing molten lava in an uninhabited area of south
Iceland and on the 14th of April the volcano erupted again from the top crater. The second
eruption caused a massive glacial flood (800 people evacuated) and it threw up volcanic ash
several kilometres into the atmosphere. The ash plume led to air traffic disruption across NW europe

Question 8

The Iceland Volcanic Observatory employs a range of methods to monitor volcanic activity so that
accurate predictions can be made:

Answer 8

• Gas sampling: changes in gas composition indicate the activity levels of magma
  underground.
• GPS technology: used to monitor any significant changes on the volcano so that the risk of
  activity e.g. pyroclastic flows can be assessed.
• Seismic monitoring: any minor earthquake activity is detected using seismographs and is
  recorded. Rising blobs of magma can cause earthquake activity and so this may be a sign
  of an eruption.

Question 9

Magnitude

Answer 9

The strength of an earthquake

Question 10

Focus

Answer 10

The point underground that shock waves travel out from

Question 11

Epicentre

Answer 11

The point on the ground above the focus where the vibration is the greatest

Question 12

Fault

Answer 12

a weak point in a tectonic plate where pressure within the crust is released

Question 13

Earthquake Case Study: Turkey-Syria 2023 Causes

Answer 13

Cause of the earthquake:

• Transform/conservative plate boundary - Anatolian plate is sliding past the Arabian
  plate.
• Tension had been building up for a long time on the East Anatolian fault.
• Pressure was released and the plates slipped along a strike slip fault.
• Shockwaves were sent out causing severe shaking of the crust.
• The earthquake measured 7.8Mv.

15
* As is the case with many earthquake events the mainshock was followed by many
aftershocks, including three above magnitude 6.0.
* Aftershocks represent minor re-adjustments along the portion of the fault that slipped at
the time of the mainshock.

Question 14

Earthquake Case Study: Turkey-Syria 2023 Impacts:

Answer 14

• 47,000+ deaths across SE Turkey and NW Syria.
• 6500 buildings in Turkey collapsed across 10 cities, including a 2000 year old castle in the
  city of Gaziantep.
• Hundreds of thousands left homeless across SE Turkey and NW Syria.
• People left to fend for themselves with many camped out in makeshift shelters in
  supermarket car parks, mosques, roadsides or amid the ruins, often desperate for food,
  water and heat.

Question 15

Structure of the earth Crust

Answer 15

A thin layer of solid rocks around the outside of the earth.
2 types of crust:
* Continental crust is crust made up of land is mainly composed of Granite.
* Oceanic crust is curst made up of oceans it is composed of Basalt.
* The earth’s crust is broken up into large slabs of rock called tectonic plates

Question 16

Structure of the earth Mantle

Answer 16

• A layer of semi-molten (melted rock)
• The thickest layer.
• Heat currents called convection currents rise and fall in the mantle.

Question 17

Structure of the earth Outer core

Answer 17

• A layer of molten (melted) rock.
• Average temperatures of 3000 degrees C.
• Composed of iron / nickel.

Question 18

Structure of the earth Inner core

Answer 18

• The centre of the earth
• Temperature of about 2700 degrees C
• Described as a solid ball of iron and nickel
• It is in a solid state due to pressure from the other layers.

Question 19

What are tectonic plates?

Answer 19

• Tectonic plates are sections of very thin crust.
• They float like rafts on the semi-molten material that makes up the earth’s mantle.
• These plates move on top of the mantle by a series of heat (convection) currents.
• The movement is very small at less than 1 cm per year, but it can result in volcanic
  eruptions and earthquakes.
• Earthquakes and volcanoes are found near plate boundaries. They can happen on the
  seabed as well as on land.

Question 20

Earthquake Management Earthquake Case Study: Turkey-Syria 2023 prediction

Answer 20

• Seismologists use GPS technology to analyse stress built up on faults. It had noted that
  there was a lot of stress on the East Anatolian fault and that this could give way at any
  time, including a large earthquake above magnitude 7.0.

Question 21

Earthquake Management Earthquake Case Study: Turkey-Syria 2023 Prevention:

Answer 21

• Turkey introduced a seismic building code after a large earthquake in 1999. However,
  many buildings pre-date the codes and some recent buildings have also not been built to
  code due to corruption (developers paid money to officials and got a certificate saying the
  building was safe)
• People in SE Turkey paid an earthquake tax - this is meant to help with relief efforts;
  however, the efforts were found to be poor with people complaining of a lack of
  equipment, expertise and support to rescue those trapped under rubble.
• Countries, such as the USA, deployed search and rescue personnel to Turkey (the US sent
  150 specialists).
• UN aid convoys were not permitted access to Syria to provide assistance until 3 days after
  the earthquake.
• The international community pledged aid to Turkey and Syria.