Yr11 - Extreme Natural Events Assessment guidance

Here are some sample questions from the Extreme Natural Events assessments and some sample answers with their grades.

1.Read the following Geographic Concept. Include specific references to it, as well as to the extreme natural event and to the environment of the case study (studies) you have named on page 2, to support your answers to this question.

 Fully explain how your named extreme natural event has affected the natural environment.

Volcanic eruptions can have many effects on natural environments. The natural vegetation is stripped bare and trees lose their leaves. Forests may be burnt. Often all the trees fall in the direction of the blast. New landforms are created and others destroyed. New cones can appear or craters fill with rainwater to create new lakes. Sometimes the eruption is so large that the top of a mountain is blown off so that its height is reduced or the sides collapse as they are unstable to form a caldera. Soils are also affected. Straight after an eruption the ash covers the ground making it hard to grow anything. However, over time the soils become more fertile. Waterways are changed by debris from lahars. If there are lots of lava flows they may fill up a river valley and change the shape of the land. Coastlines are only affected if the eruption occurs near to the sea when they can change the shape of the coastline.

Overall Mark – Not Achieved

Main Reason: No reference to a case study

2.

Read the following Geographic Concept. Include specific references to it, as well as to the extreme natural event and to the environment of the case study (studies) you have named on page 2, to support your answers to this question.

Fully explain how your named extreme natural event has affected the natural environment.

When Tarawera erupted in 1886 it had a major impact on the environment. It was a huge eruption, measuring a 4 on the Volcanic Explosivity index (VEI). This was so large that it was recorded by the ancient Chinese who saw strange red skies. The eruption started just after midnight with a series of small earthquakes. The first eruption happened about 1.30am with a huge cloud of ash. At this time most people were in their houses hiding as they were scared and did not know what to do. When the ash fell on the roofs of the houses they collapsed under the weight. 153 people were killed in 3 Maori villages such as Te Wairoa. This could have been avoided if people had been evacuated. Today scientists are much more able to predict if an eruption is likely. When Pinatubo erupted in 1991 this was also a large eruption measuring a 5 on the VEI scale. However, an effective evacuation by the government saw 370,000 people in the 30km radius of the volcano moved to safety elsewhere. This shows that volcanic eruptions can have big impacts on environments.

Overall Mark: Not Achieved

Reason: Is all on impacts of cultural environments not natural.

3.

Read the following Geographic Concept. Include specific references to it, as well as to the extreme natural event and to the environment of the case study (studies) you have named on page 2, to support your answers to this question.

Fully explain how your named extreme natural event has affected the natural environment.

When Tarawera erupted in 1886 it had a major impact on the environment. This eruption was very large measuring a 4 on the volcanic Explosivity Index meaning that it could do a lot of damage to the natural environment. One impact that it had was that it changed  lake Rotomahana. Before the eruption this lake was fairly small and well known as the site of two silica terraces called the Pink and white terraces that were a major tourist attraction at the time. When the eruption occurred just after midnight on June 10^th 1886 the hot lava hit the cold water of the lake and caused a massive explosion. The water was turned into hot mud that rained down across the whole region and buried it. A large hole was left where the lake stood. Over time this hole filled with rainwater to form the present lake. This is now more than double its original size and is 40m higher than before the eruption. This shows that volcanic eruptions can cause big changes to the shape of the environment.

Overall Mark: Not Achieved

Reason: Only one impact on the natural environment is mentioned.

 4.

Read the following Geographic Concept. Include specific references to it, as well as to the extreme natural event and to the environment of the case study (studies) you have named on page 2, to support your answers to this question.

Fully explain how your named extreme natural event has affected the natural environment.

When Pinatubo erupted in June 1991 it caused many effects on the natural environment. The vegetation that covered the mountain sides was stripped bare. The soils were made infertile causing a food shortage. The rivers that had their source on Mt Pinatubo such as the Maloma were all changed as they were unable to flow along their original path. Most dramatic of all was that a new caldera was formed that was 2.5km wide. The highest point of the caldera rim stood 260m lower than the pre-eruption summit. This shows that volcanic eruptions can change natural environments.

Overall Mark: Achieved

Reason: Has several impacts on natural environments and case study specifics. However, this is descriptive only and does not give reasons for the effects needed to lift to Merit.

5.

Read the following Geographic Concept. Include specific references to it, as well as to the extreme natural event and to the environment of the case study (studies) you have named on page 2, to support your answers to this question.

Fully explain how your named extreme natural event has affected the natural environment.

Volcanic eruptions can have many effects on natural environments as can be seen by the case studies of Tarawera (1886) and Pinatubo (1991). Both of these eruptions were very large and explosive measuring 4-5 on the VEI (Volcanic Explosivity index). Because of the size of the eruption they had major effects on relief. On Tarawera the top of the mountain split open along a 17km long line. This went through a nearby valley and as the hot magma came into contact with cold lake water it turned it to steam, ash and mud. This rained down over the area burying valleys and destroying forests. The ground was covered in up to 8m of mud that made the soils infertile for the next 10 years. Features such as the Pink and White terraces were destroyed while the holes left by the explosions later filled with rain creating new lakes such as Lake Rotomahana. In the Pinatubo eruption the explosion was so vast that it created a caldera 2.5km wide.  The river systems were all altered as they were clogged with volcanic sediment. Minerals such as lead were brought to the surface making soils infertile.

Overall Mark: Merit

Reason: Has several impacts on natural environments that are explained with good case study evidence. Lacks reference to change needed for excellence.