Earth Science Week 1 & 2 Lectures

The movement of a mass of rock, debris, or earth and/or mud down a slope.

Landslide that moves downward and outward above a curved surface, rotating around an axis parallel to the slope.

Faster landslide moving on a planar slip surface (e.g., fault, joint).

Very slow, gradual ground movement.

The force that causes the material to move downhill (gravity).

The force that resists the movement of the material (friction, strength of the material).

The angle of the slope; steeper slopes are more prone to landslides.

Amount of water in the soil; increases, friction decreases, leading to landslides.

The steepest angle at which loose material can remain stable.

A fast-moving landslide of rocks.

Fast-moving landslide of mud, rock, and debris.

Large waves generated by undersea earthquakes, landslides, or volcanic eruptions.

Shaking of the Earth's surface caused by the sudden release of energy in the Earth's crust.

Seismic waves that compress and expand the ground.

Seismic waves that shear the ground.

Seismic waves that travel along the Earth's surface.

Process in which magma, ash, and gases are ejected from a volcano.

Molten rock flowing from a volcano.

Fast-moving current of hot gas and volcanic matter.

Small fragments of rock ejected during a volcanic eruption.

Wide, gently sloping volcano formed by fluid lava flows.

Reducing the impacts of natural disasters through measures like land-use planning, insurance, and public education.

Accepting that we cannot control nature and adapting to its forces, instead of trying to dominate them.

Consists of layers with distinct chemical composition, physical state, and impacts on life on Earth's surface.

The solid, outer part of Earth comprising the crust and upper mantle, bounded by the atmosphere above and the asthenosphere below.

A theory explaining how Earth's lithosphere moves, generating major landforms, volcanoes, and earthquakes.

The movement of Earth's continents over geologic time relative to each other, appearing to have drifted across the ocean bed.

A protective shield generated by the Earth's core, deflecting harmful solar radiation.

Variations in Earth's magnetic field recorded in rocks, indicating changes in the planet's paleomagnetic field over time.

The zone where two tectonic plates interact, resulting in geological events like earthquakes, volcanoes, and mountain formation.

A plate boundary where one denser plate dives beneath another, causing volcanic activity and mountain building.

The process of new oceanic crust being created at mid-ocean ridges as plates move apart.

Different types of damage and destruction caused by earthquakes.

The primary impact of an earthquake, caused by seismic waves travelling through the Earth, which can cause buildings to collapse.

A visible displacement of the Earth's surface along a fault line due to earthquake movement.

The phenomenon where saturated soil loses strength and behaves like a liquid due to shaking, leading to ground failure.

The speed of a tsunami wave is influenced by the depth of the ocean. Deeper water allows for faster wave propagation, while shallower water slows the wave down and increases its height.

Tsunami waves are primarily generated by sudden and significant vertical movement of the ocean floor, often caused by earthquakes, underwater landslides, or volcanic eruptions.

A large magnitude earthquake (typically greater than 8) is necessary to generate a significant tsunami. The size of the rupture zone on the seafloor also plays a crucial role.

The amount of water displaced by the ocean floor movement directly impacts the size and energy of the tsunami wave. Larger and faster movements lead to bigger waves.

A large mass of material sliding into the ocean, like a landslide, can cause a tsunami. The sudden volume of water displaced triggers waves.

Volcanic eruptions, particularly those occurring underwater, can displace large volumes of water, generating tsunami waves. The speed of hot volcanic ash and submarine explosions can further amplify the wave energy.

While rare, a large asteroid impact into the ocean can create a massive tsunami. The impact creates a deep cavity, causing the surrounding water to collapse inwards, generating monstrous waves.

The height from which an asteroid impacts the ocean plays a more significant role in determining the tsunami's size than the total mass of the asteroid itself. A higher impact height results in a faster impact speed and therefore larger waves.

A magnitude 6.2 earthquake that occurred near Mount Kinabalu in June 2015, triggering rockfalls and landslides that killed several people, including Singaporean teachers and students.

A type of lava that is moderately rich in minerals and has a temperature range of 800°C - 1000°C.

A type of lava that is high in potassium and sodium, but low in iron, magnesium, and calcium. It has a lower temperature than other types, around 650°C - 800°C.

A mound of solidified lava that forms when thick, viscous lava oozes out of a vent and piles up.

A fast-moving cloud of gas and volcanic debris that jets out of a volcano and races across the landscape, forming layers of irregular ash.

A destructive mudflow triggered by volcanic eruptions. It's a mixture of mud, water, and volcanic debris.

The dangers posed by volcanic eruptions to people and the environment

The process of observing and tracking volcanic activity to predict eruptions and warn people.

Increased moisture content in soil reduces friction between soil particles, making the slope less stable and more vulnerable to landslides.

Cohesion is the force that binds soil particles together. It's mainly due to surface tension of water between the particles and helps resist landslides. Increased pore fluid pressure (deeper underground) can weaken cohesion and trigger landslides.

Rockfall is a very fast landslide where rocks tumble down a steep slope. It has a short runout because of its speed and causes patchy impacts.

Debris flow is a fast-moving landslide with a long runout, carrying a mixture of mud, rock, and debris. The impact depends on the flow's concentration, velocity, and depth.

Restricting development in areas prone to disasters.

Mitigates financial impact of disasters.

California restricts land use in active fault zones. Sellers must disclose hazard risks to buyers, but not renters. This helps minimize potential damage and protect people from risky locations.

Earthquakes can cause landslides by shaking unstable slopes, especially areas with liquefaction and steep terrain. Rainfall can worsen the risk by acting as a lubricant for surfaces to slip.

Landslides can lead to flooding. A landslide can block a river, creating a dam. When the dam breaks, a sudden release of water causes flooding.

During an earthquake, saturated soil (sand and water) can lose its strength and behave like a liquid. This liquefied soil rises to the surface, causing instability for structures built on it.

Earthquakes can cause uplift (rising) or subsidence (sinking) of land. This can change shorelines and expose areas that were previously underwater.

The system detects the fast-moving P-wave, which arrives before the damaging S-waves and surface waves. This allows for a short warning time to prepare for the stronger shaking.

It needs information about active faults, their slip rate, previous earthquakes, and how shaking intensity decreases with distance from the fault.

It provides information after an earthquake occurs, including the location and size of the earthquake. This information is updated as more data becomes available.

A system that uses sensors to detect earthquake waves and predict the intensity and arrival time of shaking at a location.

The vertical movement of the ocean floor, usually caused by earthquakes, creates waves that travel outward from the epicenter.

Tsunami waves have extremely long wavelengths, often exceeding hundreds of kilometers, and periods of several minutes.

A type of earthquake where one tectonic plate slides over another, often triggering a tsunami.

As a tsunami approaches the coast, its wavelength decreases and its height increases, leading to destructive waves.

Tsunami waves travel much faster in deep water than in shallow water.

Coastal areas are most vulnerable to tsunami damage due to the increased wave height as the tsunami approaches the shore.

The distance between two consecutive crests or troughs of a tsunami wave.

As the moisture content in soil increases, the friction between soil particles decreases. This makes the slope less stable and more likely to experience a landslide.

Cohesion is the force that binds soil particles together, usually due to the surface tension of water between them. Cohesion helps resist landslides.

Increased pore fluid pressure (deeper underground) weakens cohesion in the soil, making it easier for landslides to occur.

Debris flows are fast-moving landslides with a long reach. They carry a mixture of mud, rock, and debris. Impact severity depends on the flow's size, speed, and depth.

A massive volcanic crater formed by an ultra-plinian eruption, over 100 kilometers in scale, located in Sumatra (Indonesia).

Rocks formed from the cooling and solidification of magma or lava.

Extrusive igneous rocks form when lava cools rapidly on the Earth's surface, creating fine-grained textures. Intrusive igneous rocks form when magma cools slowly underground, creating coarse-grained textures.

Silica content in magma influences its viscosity (fluidity). Higher silica content leads to a stiffer magma, while lower silica content results in more fluid magma.

Water content in magma influences its viscosity and explosiveness. More water increases fluidity and explosiveness, especially for rhyolitic magma.

A tall column of gas and volcanic debris ejected into the atmosphere during a Plinian eruption, characterized by high ash content and powerful gas blasts.

Magma composed of high iron, magnesium, and calcium content with low potassium and sodium, resulting in low-viscosity, fluid lava.

Earth's surface is much rougher than Mars due to its dynamic nature. It is more active, with forces deforming the crust and creating textures that reflect varying loadings.

The exponential growth of the human population increases the impact of natural disasters. More people and infrastructure in vulnerable areas lead to greater damage and casualties.

Natural disasters arise from the interaction of Earth's different spheres, like the hydrosphere, biosphere, and atmosphere. These interactions create complex and sometimes catastrophic events.

Many natural events have predictable cycles. However, predicting the impact on a global scale is difficult because of numerous variables and overlapping cycles.

The magnitude of a natural event is inversely proportional to its frequency. Larger events occur less frequently.

Some natural processes create a feedback loop, accelerating the changes. For example, melting ice leads to darker oceans, which absorb more heat, causing more ice to melt.

Multiple natural events can occur simultaneously, amplifying their impact. For example, a storm surge during high tide can create extremely high tides.

Human impact on natural disasters is influenced by factors like population density, location, and preparedness. Higher population density and inadequate infrastructure lead to increased casualties and damage.