Geological Hazards Notes

What are the primary chemical components of the Earth's crust?

Oxygen, Silicon, Aluminum, Iron, Calcium, Sodium, Potassium, Magnesium.

What is the density formula for calculating density?

Density (p) = Mass (m) / Volume (V).

What is Earth’s average density based on accepted values for its volume and mass?

5.42 g/cm^3.

What are the two main types of crust on Earth?

Oceanic crust and Continental crust.

What is the dominant rock type found in Earth’s shallow interior?

Peridotite.

What is isostasy in relation to Earth's crust?

Isostasy is the equilibrium between gravity and the buoyancy force, describing how pieces of Earth's crust float on the asthenosphere.

Who is Arthur Holmes and what was his contribution to geochronology?

Arthur Holmes was a British geologist known as the father of modern geochronology who pioneered the use of radiometric dating.

What does the elastic rebound theory describe?

It describes how stress applied to rock results in strain, which builds up until it exceeds static friction, resulting in an earthquake.

What are the characteristics of a normal fault?

In a normal fault, the hanging wall drops down relative to the footwall, associated with extensional stress.

What is a strike-slip fault characterized by?

A strike-slip fault is characterized by side-to-side movement with no fault scarp, footwall, or hanging wall.

What is the relationship between temperature and depth in the Kola Borehole?

At a depth of 12.3 km, temperatures reach up to 180 degrees Celsius.

Why can't scientists directly sample the Earth's interior?

Due to extreme heat and high pressure.

What minerals dominate peridotite?

Olivine and pyroxene.

How do seismic waves contribute to understanding Earth’s interior?

Seismic waves provide information about the physical states and structure of materials within the Earth.

What determines the buoyancy of continental versus oceanic crust?

Continental crust is more buoyant due to its greater thickness and mass/area compared to oceanic crust.