Earth's Interior and Earthquake Basics

The point inside Earth where an earthquake originates. Usually located 100-200 km deep.

Sudden movement or vibration on Earth's surface caused by the release of energy due to tectonic activity.

The point on Earth's surface directly above the focus. It experiences the strongest earthquake effects.

Seismic waves that travel through the Earth's interior.

The fastest seismic wave. It moves parallel to the direction of wave propagation. Can travel through both solids and liquids.

Slower than P-waves. It moves perpendicular to the direction of wave propagation. Only travels through solids.

The slowest seismic wave. It travels along the Earth's surface. Causes the most destruction.

An instrument that detects and records seismic waves.

The process of digging deep into the Earth to extract rocks and minerals, providing insights into the structure and composition of the Earth's crust.

A technique for reaching deep into the Earth to explore and extract resources, offering clues about the layers beneath the surface.

Waves of energy that travel through the Earth, generated by earthquakes, providing valuable information about the planet's interior.

The region within the Earth where earthquake waves cannot pass, creating a 'shadow' zone on the seismograph.

The outer layer of the Earth, made of different types of rocks and minerals, ranging in thickness.

The thick layer beneath the Earth's crust, made of hot, dense, semi-solid rock, playing a role in plate tectonics.

The Earth's innermost layer, composed primarily of iron and nickel, with a solid inner core and a liquid outer core.

Seismic waves that travel along the Earth's surface.

Primary waves, also known as compressional waves, are seismic waves that travel through the Earth's interior by compressing and expanding the material they pass through. They move faster than S waves and can travel through solids, liquids, and gases.

Secondary waves, also known as shear waves, are seismic waves that travel through the Earth's interior by vibrating the material they pass through perpendicular to their direction of travel. They are slower than P waves and can only travel through solids.

Rayleigh waves are surface waves that cause a rolling or elliptical motion of the ground. They are named after Lord Rayleigh, who first described their properties. Rayleigh waves are the slowest of the seismic waves and cause the most damage.

The region where seismic waves are not recorded due to their inability to pass through the Earth's core. This zone exists for both P and S waves, but the shadow zone is much larger for S waves because they cannot travel through the liquid outer core.

The Richter scale is a logarithmic scale that measures the magnitude of earthquakes based on the amplitude of seismic waves recorded by a seismograph. Each whole number increase on the Richter scale represents a tenfold increase in the amplitude of the seismic waves.

The liquid layer of the Earth's core, primarily composed of iron and nickel.

The solid, dense center of the Earth, mainly composed of iron and nickel.

The study of how seismic waves travel through the Earth to understand its internal structure.

The process of measuring the Earth's density by analyzing meteorites, which are believed to be formed from the same material as the early Earth.

The thickest part of the crust, found beneath the continents.

The thinner part of the crust, found beneath the oceans.

A logarithmic scale used to measure the strength or magnitude of an earthquake. Each whole number increase on the scale represents a tenfold increase in the amplitude of seismic waves and approximately 32 times more energy released.

A measure of ground shaking during an earthquake. It describes the effects of the earthquake on people, structures, and the Earth’s surface.

A series of waves caused by the displacement of a large volume of water, often triggered by an underwater earthquake.

A seismic wave with a magnitude of 2.5 or less, often too small to be felt by humans.

The point beneath the Earth's surface where an earthquake originates.

The process of soil liquefaction occurs when saturated soil loses its strength and behaves like a liquid during intense ground shaking, often caused by earthquakes.

The upper part of the mantle, which is partially molten and behaves like a 'plastic' solid. It is the source of magma.

The rigid outer layer of the Earth consisting of the crust and the uppermost part of the mantle.

The layer beneath the mantle, extending from 2900 km to 6300 km. It is composed of liquid iron and nickel and is responsible for Earth's magnetic field.

The innermost layer of the Earth, located at the center. It is composed of solid iron and nickel and is extremely hot due to immense pressure.

A place on the Earth's surface where molten rock (lava), gases and ash escape from the Earth's interior.

The molten rock that erupts from a volcano.