4.1.4 Geological Hazards

Geological Hazards

4.1.3

Objectives

Learners can:

• describe the formation of a volcano

• differentiate between different types of volcanic eruptions

• identify the processes that lead to an earthquake

• evaluate systems used to measure the impact of an earthquake

• lava

• magma

• plate tectonics theory

Prerequisite Vocab

• earthquake

• landslide

• magnitude

• tsunami

• volcano

New Vocab

Vocabulary

​a sudden shaking of the ground caused by the movement of rock underground

Earthquake

sudden movement of rocks or soil down a hill or mountainside

Landslide

strength of an earthquake

Magnitude

a large ocean wave caused by an underwater disturbance

Tsunami

a mountain formed by lava and pyroclastic material

Volcano

Match

Match the vocabulary word to its definition.

• magma

• lava

• plate tectonics theory

melted rock located beneath Earth

melted rock on Earth's surface

individual plates that gradually move

• melted rock located beneath Earth

• melted rock on Earth's surface

• individual plates that gradually move

Krakatoa is a volcanic island group located in Indonesia. The island has a long history of volcanic activity. One of the most famous eruptions occurred in 1883.

The eruption caused widespread destruction. Nearly 36,000 people died as entire villages were destroyed. The Krakatoa eruption also had far-reaching impacts, as the debris from the explosion caused global average temperatures to drop for many years.

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Krakatoa

Types of Geological Hazards

An earthquake is a sudden shaking of the ground caused by the movement of rocks underground.

As Earth's crust moves, the rocks near the plate boundaries will bend and eventually break. The breaking of rock releases the energy that causes earthquakes.

The bending and breaking of rock are similar to the process of breaking a pencil.

Earthquakes

Earthquakes are most likely to happen in areas where two plates meet. The red arrows in the map show where two plates are pushing together, pulling apart, or sliding past each other. These movements have the potential to release the energy that causes earthquakes.

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Tectonic Plate Boundaries

Magnitude is the strength of an earthquake. bout 30,000 earthquakes occur every year that are measurable. Only a few of these earthquakes are great enough in magnitude to cause significant destruction. An increase of one magnitude on the scale means that the earthquake is 10 times as powerful.

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Magnitude Scale

A volcano is a mountain formed by lava and pyroclastic material. There are approximately 500 active volcanoes worldwide. Many of these volcanoes are found along tectonic plate boundaries.

A volcanic eruption occurs as magma rises to Earth's surface. Volcanic eruptions often result in the release of lava, gases, and pyroclastic material. Pyroclastic material includes rocks and ash that erupt from the volcano.

Volcanic Eruptions

• high percentage of silica

• high thickness

• large quantity of dissolved gases

• violent and explosive

Felsic

• a lower percentage of silica

• thinner magma

• low quantity of dissolved gases

• gentle and quiet

Mafic

Due to the pyroclastic material from eruptions, the soil around volcanoes tends to be fertile. Nutrients from the blast, such as phosphorus, potassium, and nitrogen, provide the necessary nutrients for plant growth.

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Sometimes it is greener on the other side

Landslides are sudden movements of rocks or soil down a hill or mountainside. When large amounts of materials break loose from a cliff or hillside, they move quickly and with tremendous force. Landslides can move as fast as 150 miles per hour.

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Landslides

Rockfalls occur when rocks or boulders break from a cliff or slope and tumble down.

Rockfall

A mudflow is a mixture of soil, rocks, and water that rushes down a slope.

Mudflow

A creep is a slow, gradual movement of soil or rock downhill.

Creep

An avalanche is a rapid type of landslide that involves snow, ice, and rock.

​​Avalanche

A tsunami is a large ocean wave caused by an underwater disturbance. Unlike most ocean waves that form from wind movement, tsunamis usually form due to underwater volcanic eruptions, earthquakes, or landslides.

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Tsunami

Open Ended

Choose one geological hazard and briefly describe the impact that hazard can have on humans and the environment.