Natural Disasters Unit 1 Study Guide

Comprehensive vocabulary flashcards covering Unit 1: Introduction to Natural Hazards, Mass Wasting processes, Tsunami wave development, and Hazard Mitigation strategies.

Scientific Hypothesis

A testable prediction for a specific observation.

Scientific Theory

A well-tested and proven explanation, supported by many observations, for why something happens.

Theory of Plate Tectonics

A well-tested explanation backed up by evidence explaining that Earth's outer shell is divided into large moving plates that move over the mantle.

Frequency (Hazard)

How often a hazard occurs.

Magnitude (Hazard)

The size of a hazard.

Magnitude and Frequency Relationship

An inverse relationship in natural hazards where as one increases, the other decreases.

Angle of Repose

How steep a slope can get before material collapses or slides.

Subsidence

A type of mass wasting that occurs when material drops downward, qualifying as mass wasting because it involves the downward movement of Earth materials.

Criteria for Classifying Mass Wasting

The three standards used to classify mass wasting: material (rock, soil, regolith), speed (fast, slow), and environment (subaerial, submarine).

Soil

Loose organic material involved in mass wasting.

Rock

Solid, un-weathered material.

Regolith

Weathered rock and mineral fragments, consisting of a mixture of sand, dirt, soil, and rock.

Submarine Mass Wasting

Mass wasting that occurs underwater.

Subaerial Mass Wasting

Mass wasting that occurs on land or on Earth's surface.

Slope Steepness (Stability Factor)

A primary factor influencing slope stability where the steeper the slope, the less stable it is.

Slope Material Composition (Stability Factor)

A factor influencing stability where clay and shale slopes are less stable, solid rock (like granite) tends to be more stable, and larger material maintains a higher angle of repose.

Slope Friction (Stability Factor)

The resistance along a slope that can be decreased by wildfires, the removal of vegetation, and the addition of water.

Trigger Stage (Tsunami)

The initiating event that causes a tsunami wave to form.

Wave Propagation Stage (Tsunami)

The phase where tsunami waves move outward from the point of origin in a circular pattern, with motion reaching down to the ocean floor.

Deep Ocean Tsunami Characteristics

Tsunami behavior in deep water where waves travel at speeds of up to $500\,\text{mph}$ with very long wavelengths and short wave heights.

Approaching Shoreline Tsunami Characteristics

Tsunami behavior in shallow water where wave speed slows down drastically, wavelengths decrease, wave height builds tall, and wave frequency increases.

Tsunami Trough Arrival

The arrival of the low point of a tsunami wave at the coast first, producing a noticeable lowering or receding of the seafloor before the incoming crest arrives shortly after.

Tsunami Warning Systems

A mitigation method consisting of ocean equipment that issues warnings within a few minutes or less when a tsunami is detected.

Runup Maps

Hazard maps that display coastal inundation zones that should be evacuated and avoided during a tsunami.

Seawalls

Barriers built parallel to the coast intended to prevent tsunami waves from pushing inland.

Building Codes (Tsunami Mitigation)

Structural mitigation standards that involve designing safe spaces within buildings, retrofitting existing structures, and constructing new buildings to withstand incoming water.

Vegetation (Tsunami Mitigation)

Coastal plant cover that significantly reduces wave severity by absorbing and dissipating incoming wave energy.