ESCI weel 3-4

Evolution

The process of change in living organisms over generations, leading to the diversity of life forms we see today.

Natural Selection

The mechanism by which organisms better adapted to their environment tend to survive and produce more offspring.

Homologies

Similarities in body parts between different organisms, indicating a common evolutionary ancestor.

Asthenosphere

The mechanically weak layer of the upper mantle where tectonic plates move, containing a small amount of liquid melt.

Plate Tectonics

The theory explaining the large-scale motion of Earth's lithosphere, driven by convection currents in the mantle.

Pangea

The supercontinent that existed around 300 to 200 million years ago, comprising most of Earth's continental crust.

Rift

A divergent plate boundary where two plates move away from each other, leading to the formation of new crust.

Continental Crust

The outermost layer of Earth's lithosphere, composed of less dense elements like Na, K, Ca, Si, Al, and O.

Oceanic Crust

Newly solidified magma composed of relatively dense elements such as Mg, Fe, Ca, Si, Al, and O, formed from mantle magma.

Divergent Plate Boundaries

Plate boundaries where two plates move apart, leading to the creation of oceanic crust during the post-rift stage.

Continental Crust vs

Continental crust is thicker (35-40 km) and less dense (2.7 g/cm3) compared to oceanic crust (6-10 km thick, 3.0 g/cm3).

Subduction

Process at convergent plate boundaries where denser oceanic lithosphere sinks into the mantle beneath another tectonic plate.

Transform Plate Boundaries

Plate boundaries where two plates slide past each other horizontally, without creating or destroying lithosphere.

Plate Boundaries

Regions where tectonic plates interact, causing most deformation and geohazards, such as earthquakes and volcanoes.

Elastic Rebound Theory

Theory stating that strain energy accumulates on a locked fault between earthquakes, released during an earthquake.

Seismic Cycle

Concept describing events before, during, and after an earthquake, involving interseismic, coseismic, and postseismic phases.

Types of Earthquakes

Different stress states lead to Normal (pulling apart), Strike-Slip (side to side), and Reverse (one block moves up) faulting.

Local Magnitude (ML)

A magnitude scale calculated based on the amplitude of shaking recorded by a seismometer with respect to a reference event, estimated using the difference in S-wave and P-wave arrival times.

Seismic Moment (M0)

A measure of the energy released during an earthquake, calculated as the product of shear modulus, rupture area, and average displacement.

Moment Magnitude (Mw)

A scale used by seismologists to quantify earthquakes today, calculated from seismic moment, providing a better estimate of energy released than local magnitude and allowing comparison globally.

Seismometer

An instrument that records signals generated by earthquakes, volcanic eruptions, and explosions, providing information on the direction, intensity, and duration of shaking.

P Waves

Primary waves that travel through gases, liquids, and solids, arriving first at a site/seismograph by compressing and expanding material parallel to their propagation direction.

S Waves

Secondary waves that can only travel through solids, arriving second at a site/seismograph by causing material to move back and forth perpendicular to their travel direction, leading to higher amplitude shaking.

Surface Waves

Elastic waves that propagate through solids, including Love waves that move material horizontally and Rayleigh waves that move material elliptically, causing destructive effects.

Modified Mercalli Intensity Scale

A scale characterizing earthquake intensity based on shaking effects on people, structures, and the landscape, with isoseismal lines connecting areas of equal intensity.

Seismic Hazards

Physical phenomena associated with earthquakes that can lead to loss of life, property, or income, including primary hazards like ground shaking and secondary hazards such as tsunamis and landslides.

Disaster Risk Reduction

The process of reducing risk posed by natural hazards by quantifying hazard characteristics, assessing vulnerability, and enhancing capacity to cope, withstand, and recover from hazard impacts.