Geology, Plate Tectonics, Earthquakes, and Structural Framing Systems

Vocabulary practice flashcards generated from lecture notes on geology, tectonic plates, earthquake mechanisms, and structural framing systems.

Geosphere

The sequence of shells and layers that conceived the earth, the heaviest of which forms the core.

Barysphere

Also known as the core; the densest central part of the earth composed of an inner core and an outer core.

Asthenosphere

Also known as the mantle; a $2685\,\text{km}$ thick layer surrounding the core composed of hot, dense ultrabasic igneous rock in a plastic state with a density of $5000\text{--}6000\,\text{kg/m}^3$.

Lithosphere

Also known as the crust; the thinnest outer solid shell of the earth, about $200\,\text{km}$ thick with a density of $1500\,\text{kg/m}^3$.

Tectonic Plates

Gigantic rigid rock plates of about $80\,\text{km}$ in thickness that make up the earth's crust.

Plate Tectonics

The process where rigid crustal plates move in different directions and at different speeds relative to each other at a rate of $5$ to $10\,\text{cm}$ per year on the plastic mantle.

Convergent Boundary (Destructive Margin)

A plate boundary that occurs when two plates move from opposite directions towards each other and collide, pushing upwards to form major mountain systems.

Divergent Boundary (Constructive Margin)

A plate boundary that occurs when two tectonic plates move away from each other, such as the Mid-Atlantic Ridge.

Transform Boundary (Conservative Margin)

Places where tectonic plates slide sideways past each other without creating or destroying lithosphere, such as California's San Andreas Fault.

Active Fault

A fault that has moved within the last $10,000$ years, showing evidence or documented history of its recent movement.

Philippine Fault

A $1,300\,\text{km}$-long fault traversing from Ilocos Region in the north to eastern Mindanao in the south, responsible for most inland earthquakes in the Philippines.

Elastic Rebound Theory

Theory proposed by M.F. Reid in 1906 stating that tectonic earthquakes occur due to the gradual accumulation of strain up to the elastic limit of rock, which then ruptures and snaps back, releasing stored energy as vibrations.

Interplate Earthquakes

Earthquakes that occur along the boundaries of tectonic plates, such as the Great Assam Earthquake in 1950.

Intraplate Earthquakes

Earthquakes that occur within the tectonic plates themselves, away from plate boundaries, such as the Latur Earthquake in 1993.

Dip-Slip Fault

A fault movement generated during an earthquake along both horizontal and vertical directions, categorized into normal and reverse faults.

Strike-Slip Fault

A fault movement generated during an earthquake where movement occurs along the lateral direction parallel to the strike of the fault.

Focus (Center)

The point of generation of an earthquake within the earth.

Epicenter

The point on the earth's surface directly above the focus of an earthquake.

P-Waves (Primary Waves)

Body waves that cause push-and-pull ground motions involving compression and extension in the direction of energy transmission.

S-Waves (Secondary Waves)

Body waves that produce up-and-down or side-to-side transverse motions relative to the direction of energy transmission.

Love Waves

Surface waves resulting from interaction between body waves and surface layers that cause ground motion sideways in a horizontal plane.

Rayleigh Waves

Surface waves that cause ground particles to move elliptically in a vertical plane.

Accelerogram

A record showing the vibration of ground acceleration over time recorded at a point on the ground during an earthquake.

Earthquake Intensity

A non-instrumental, qualitative measure of earthquake severity based on observed effects on people, structures, and the ground surface, represented by Roman capital numerals.

Earthquake Magnitude

A quantitative measure of the actual size or amount of energy released at the focus of an earthquake, based on direct wave amplitude measurements and represented by Arabic numbers.

Isoseismals

Lines on a map connecting places with equal seismic intensity during an earthquake.

Ground Rupture

Deformation on the ground surface marking the intersection of a fault with the earth's surface, causing fissuring and ground displacement.

Liquefaction

A process wherein loose, saturated sediments behave like a liquid during earthquake shaking, causing structures above to sink or tilt.

Earthquake-Induced Landslide

The downslope movement of rocks, soil, and debris triggered by strong shaking during an earthquake.

Tsunami

A series of water waves commonly caused by an undersea earthquake, resulting in coastal flooding and erosion.

Bearing Wall System

A structural system using shear walls to support most gravity loads and resist all lateral forces, characterized by a lack of redundancy and low response modification coefficient $R$.

Moment-Resisting Frame System

A structural framing system providing support for both gravity and lateral loads without diagonal bracing or shear walls, utilizing rigid joints and high inelastic deformation capacity.

Building Frame System with Shear Walls

A structural system consisting of two independent systems: shear walls that resist all lateral loads, and a column and beam frame supporting most gravity loads.

Special Steel Concentrically Braced Frames

Braced frames where centerlines of frame members, beams, columns, and braces are coincident, resisting lateral loads through axial forces in the members.

Buckling-Restrained Braced Frame

A concentrically braced frame using braces made of a steel core surrounded by steel and mortar casing to prevent buckling, yielding higher ductility and response modification coefficient $R$.

Steel Eccentrically Braced Frame

A braced frame where one end of the brace connects to the beam to form a short link that acts as a structural fuse by providing inelastic behavior.

Dual System

A structural framing system combining a primary lateral force-resisting system (shear walls or braced frames) with a secondary moment frame that must resist at least $25\%$ of the seismic forces.

Cantilever Column System

A structural system supported on columns cantilevering from their base, lacking redundancy and subject to high flexibility, drift, and P-delta instability.

Torsional Irregularity

A horizontal structural irregularity where either over $75\%$ of a story's lateral strength is provided on one side of the center of mass, or the Torsional Irregularity Ratio ($\text{TIR} = \frac{\Delta_{\max}}{\Delta_{\text{avg}}}$) exceeds $1.2$.

Re-entrant Corner Irregularity

A horizontal structural irregularity where both plan projections of a structure beyond a re-entrant corner are greater than $20\%$ of the plan dimension in that direction.

Diaphragm Discontinuity Irregularity

A horizontal irregularity existing when a diaphragm has cutouts or open areas greater than $25\%$ of the gross enclosed area or a change in effective stiffness exceeding $50\%$ between adjacent stories.

Stiffness-Soft Story Irregularity

A vertical irregularity where a story's lateral stiffness is less than $70\%$ of the story above, or less than $80\%$ of the average stiffness of the three stories above.

Stiffness-Extreme Soft Story Irregularity

A vertical irregularity where a story's lateral stiffness is less than $60\%$ of the story above, or less than $70\%$ of the average stiffness of the three stories above.

Vertical Geometric Irregularity

A vertical structural irregularity where the horizontal dimension of the seismic force-resisting system in any story is more than $130\%$ of that in an adjacent story.

Weight (Mass) Irregularity

A vertical irregularity defined to exist where the effective mass of any story is more than $150\%$ of the effective mass of an adjacent story.