Disaster Science: Earth Systems, Hazards, and Atmospheric Processes

Vocabulary practice flashcards covering fundamental Disaster Science topics: internal Earth structure, plate tectonics, coastal processes, tsunamis, fluvial flooding, mass wasting, and meteorological hazards.

Oblate Spheroid

The geometric shape of the Earth, featuring an average radius of approximately $6371\,\text{km}$, slightly flattened at the poles with an equatorial radius that is larger by approximately $22\,\text{km}$.

Asthenosphere

A ductile layer of the upper mantle approximately $250\,\text{km}$ thick located below the lithosphere, composed of solid rock that flows easily under heat and pressure.

Mantle Convection

The circulatory process within the mantle where heated solid rock rises from near the outer core toward the upper lithosphere, cools, and circles back down, driving the motion of lithospheric plates.

Geosphere

A collective term encompassing the solid lithosphere, the liquid hydrosphere, the gaseous atmosphere, and the frozen cryosphere, which together interact to sustain the biosphere.

Pack Ice

A large mass of floating ice characteristic of the Arctic Ocean, formed when winds or ocean waves drive frozen seawater (sea ice) together.

Troposphere

The lowest layer of the Earth's atmosphere, characterized by a constant drop in temperature as altitude increases.

Stratosphere

The atmospheric layer extending from roughly $18\,\text{km}$ to $50\,\text{km}$ above the surface, situated directly above the troposphere and containing nearly all of Earth's atmospheric ozone ($\text{O}_3$).

Greenhouse Effect

The warming of Earth's surface and lower atmosphere caused by atmospheric gases (such as carbon dioxide and water vapor) absorbing and reradiating emitted infrared radiation.

Natural Hazard

A naturally occurring physical event or phenomenon that has the potential to cause adverse effects or harm to human life, property, or society.

Disaster

A hazardous event that has already occurred and caused substantial loss, damage, or harm to human life and society.

Technological Disaster

A catastrophic event with an identifiable cause resulting from human error or failure in handling, operating, and managing technology.

Exposure

The situation of people, infrastructure, housing, production capacities, and other tangible human assets located within hazard-prone areas.

Vulnerability

The susceptibility of a population, building, or asset to suffer damage and adverse effects when impacted by a hazard, governed by physical, social, economic, and environmental factors.

Disaster Risk

The probability of harmful consequences or expected losses resulting from interactions between natural or human-induced hazards, exposure, and vulnerable conditions.

Habagat

The Southwest Monsoon affecting the Philippines typically from June to September, originating from the west/southwest and characterized by warm, humid air, cumulus clouds, and heavy rainfall.

Amihan

The Northeast Monsoon affecting the eastern section of the Philippines from October to March, originating from the eastern part of the world and characterized by cold, dry air, cirrus clouds, and light rains.

Tectonic Cycle

The grand cyclic recycling and deformation of the upper few hundred kilometers of the Earth's crust and upper mantle over geologic time.

Uniformitarianism

A foundational geological principle formulated by James Hutton asserting that natural laws and physical processes operating in the present produced the features of the past and will continue to operate into the future.

Philippine Mobile Belt

The complex, highly deformed convergent boundary zone between the Eurasian Plate and the Philippine Sea Plate on which the majority of the Philippine archipelago lies.

Philippine Fault Zone

A major left-lateral strike-slip fault system cutting longitudinally across the Philippine archipelago roughly parallel to the Philippine Trench.

Sunda Plate

The portion of the Eurasian Plate underlying western components of the Philippines, specifically encompassing Palawan, the Calamian islands, the Sulu archipelago, and the Zamboanga Peninsula.

Tsunami

A series of ocean waves with extraordinarily long wavelengths caused by the sudden vertical displacement of the seafloor or large standing water bodies, typically by submarine earthquakes, volcanic explosions, or mass wasting.

Wave Base

The maximum water depth at which orbital wave motion can still be detected, geometrically equal to one-half of the wave's total wavelength ($\frac{1}{2}\lambda$).

Drawdown

The conspicuous retreat and seaward recession of coastal ocean water exposing the foreshore, occurring when the trough of a tsunami wave arrives at the coast prior to its crest.

Tsunami Run-up

The maximum inland and vertical extent of water reached on land as a tsunami wave crest rushes onshore.

Edge Waves

Tsunami wave energy trapped parallel to the coastline that reverberates back and forth between incoming offshore swells and receding shorelines, preventing the initial surge from necessarily being the largest.

Inundation

The temporary covering by water of dry land areas that are not normally submerged, caused by swollen water bodies overflowing their margins or local drainage accumulation.

Bankfull Stage

The critical river water level or flood stage at which discharge begins to spill over stream channel banks and submerge the adjacent floodplain.

Lag Time

The temporal delay between the midpoint of peak precipitation in a catchment basin and the subsequent arrival of peak discharge in the draining river system.

Flash Flood

An intense upstream flooding event with an exceptionally short lag time (often within hours) triggered by localized, torrential rainfall over surfaces with low infiltration capacity.

Storm Surge

An abnormal, dangerous rise of coastal sea level generated primarily by the atmospheric pressure drop and forceful onshore winds associated with a passing cyclone.

River Channel Orientation

The anatomical orientation of a stream network relative to water movement, where 'Right Bank' and 'Left Bank' are defined when facing downstream toward the river mouth.

Angle of Repose

The steepest inclination angle relative to the horizontal plane at which loose, dry granular materials can remain stable without cascading down a slope.

Montmorillonite Clay

A highly hydrophilic and expansive clay mineral characterized by an exceptional capacity to adsorb water molecules, swelling significantly and rapidly losing shear strength when hydrated.

Undercutting

The erosive action of flowing water removing supporting soil or rock at the toe of a bank, cliff, or coastline, steepening slopes beyond their angle of repose and prompting mass wasting.

Mudflow

A rapid and fluid mass movement of fine-grained sediment saturated with water, possessing enormous momentum capable of moving massive debris and structures.

Landslide Instrumentation

A comprehensive network of geotechnical sensors—such as extensometers, crackmeters, tilt sensors, inclinometers, and rain gauges—installed along vulnerable slopes to detect early displacement.

Subsidence

The gradual settling or sudden sinking of the Earth's land surface caused by subsurface removal of fluids (such as groundwater extraction), mining, or seismic liquefaction.

Advection

The bulk horizontal transfer of thermal energy or atmospheric properties caused by the directional movement of an air mass across differing temperature gradients.

Coriolis Effect

The inertial deflection of air masses and moving bodies caused by Earth's planetary rotation, turning trajectories clockwise to the right in the Northern Hemisphere and counterclockwise to the left in the Southern Hemisphere.

Intertropical Convergence Zone (ITCZ)

A low-pressure latitudinal belt near the equator where the trade winds of the Northern and Southern Hemispheres converge, forcing warm, moist air upward into towering convective storms.

Warm Front

A meteorological boundary where an advancing warm air mass slides up and over a denser, retreating cold air mass, typically marked by cirrus, stratus, and nimbostratus clouds producing steady precipitation.

Tropical Cyclone

A non-frontal, warm-core synoptic-scale weather system characterized by organized deep convection, closed surface wind circulation, and spiraling rain bands developing over warm tropical waters.

Super Typhoon (STY)

The highest category in the PAGASA tropical cyclone scale, designated for cyclones that attain maximum sustained wind speeds exceeding $220\,\text{kph}$ (more than $120\,\text{knots}$).

Cyclogenesis

The atmospheric process involving the initiation, development, and intensification of a cyclonic circulation, requiring warm ocean waters of at least $26^\circ\text{C}$, high tropospheric humidity, and low vertical wind shear.

Squall Line

A narrow, multi-cell convective band of severe thunderstorms stretching up to hundreds of kilometers in length that advances rapidly, producing intense precipitation, sudden wind gusts, and hail.

Downburst

A concentrated, severe downdraft of cool air originating within a convective storm that slams directly into the surface and rapidly spreads outward horizontally with destructive force.

El Niño - Southern Oscillation (ENSO)

A coupled ocean-atmosphere climate cycle across the tropical Pacific characterized by alternating episodes of unusually warm sea surface temperatures (El Niño) and unusually cold waters (La Niña).