Earthquake Engineering and Plate Tectonics

Flashcards covering the fundamentals of earthquake engineering, plate tectonics, Earth's structure, and seismic wave behavior as discussed in the Structural Engineering specialized course.

Earthquake Engineering

A specialized branch of civil and structural engineering focusing on understanding how earthquakes affect infrastructure like buildings, bridges, and dams to protect human life and minimize damage.

Elastic Design Philosophy

A design approach where a structure remains entirely within its elastic range, returning to its original shape without permanent deformation, following Hooke's law where stress is directly proportional to strain.

Plastic Design Philosophy

A design approach summarized by the principle 'Accept damage, but prevent collapse,' allowing controlled yielding and irreversible plastic deformation during major earthquakes.

Plastic Hinges

Intentionally detailed structural elements designed to yield first during an earthquake to prevent brittle failure in critical components like columns and beam-column joints.

Theory of Plate Tectonics

The fundamental scientific theory explaining the movement of Earth's lithosphere and the processes behind earthquakes, volcanic eruptions, and mountain formation.

Continental Drift

An earlier theory proposed by Alfred Wegener in 1912, which was later combined with seafloor spreading to form the foundation of modern plate tectonics.

Continental Crust

The less dense, outermost solid layer of Earth mainly composed of granite, with a thickness of $30-70\,km$.

Oceanic Crust

The denser outermost solid layer mainly composed of basalt, with a thickness of $5-10\,km$.

Mantle

The layer extending to approximately $2,900\,km$ below the surface, making up nearly $84\%$ of Earth’s volume.

Outer Core

A layer of liquid iron and nickel approximately $2,200\,km$ thick that is responsible for generating Earth's magnetic field.

Inner Core

The solid iron and nickel center of the Earth where temperatures exceed $5,000^\circ\text{C}$ and extremely high pressure maintains its solid state.

Lithosphere

The rigid layer extending from the surface to about $100-200\,km$ deep, broken into massive tectonic plates that fracture under stress.

Asthenosphere

A partially molten, ductile layer extending from $100\,km$ to $700\,km$ deep that provides the 'lubricant' for tectonic plate movement.

Mantle Convection

The mechanism where heat from the core causes hot mantle material to rise and cooler material to sink, creating currents that drag tectonic plates.

Ridge Push

A mechanism where gravity causes newly formed crust at mid-ocean ridges to slide away, pushing tectonic plates apart.

Slab Pull

The strongest driving force behind plate movement, occurring when the densest oceanic lithosphere sinks into the mantle at subduction zones.

Divergent Boundary

A boundary where plates move away from each other, resulting in the formation of new oceanic crust, volcanic eruptions, and rift valleys.

Convergent Boundary

A boundary where plates move toward one another, resulting in oceanic-continental, oceanic-oceanic, or continental-continental collisions.

Transform Boundary

A boundary where plates slide horizontally past each other, resulting in numerous shallow earthquakes with no crust created or destroyed.

Elastic Rebound Theory

A theory first proposed by Harry Fielding Reid after the 1906 San Francisco earthquake explaining how rocks store elastic energy and suddenly rupture to release seismic waves.

Primary Waves (P-waves)

The fastest body waves that travel through solids, liquids, and gases using compression and expansion particle motion parallel to the wave direction.

Secondary Waves (S-waves)

Body waves that travel only through solids with shear motion perpendicular to the wave direction, introducing significant lateral forces to structures.

Love Waves

Surface waves that move the ground side-to-side horizontally, characterized by very high damage potential for structures.

Rayleigh Waves

The slowest seismic waves that move with a rolling elliptical motion, often responsible for the majority of structural failures due to extreme displacement.

National Structural Code of the Philippines (NSCP)

The set of seismic provisions engineers in the Philippines follow to ensure infrastructure possesses adequate strength, ductility, and detailing to withstand earthquakes.