Tsunamis and Submarine Mass Wasting

Vocabulary flashcards covering the mechanisms, characteristics, historical examples, and risk factors of tsunamis and submarine mass wasting.

Tsunami

A massive wave caused by a sudden shock, requiring mass movement that affects the ocean or a large body of water.

Submarine slumps

A type of submarine mass wasting where semi-coherent blocks move downslope.

Submarine debris Flow

A type of submarine mass wasting in which moving layers break apart to form a slurry.

Turbidity currents

A type of submarine mass wasting where sediment disperses and forms a turbulent cloud.

The Storegga Slide

A massive submarine landslide that occurred $8000\,\text{years}$ ago where a $5000\,\text{km}^3$ section of Norway's continental shelf slid away, destroying a Stone Age Village along the North Sea Coast.

Passive continental margins

Tectonic margins globally, including the U.S. East Coast, where large submarine landslide deposits commonly appear and pose a possible tsunami risk.

Mass Wasting Risk Mitigation

Engineering and management methods used to lessen mass movement risk, including revegetating a slope, lowering a water table, relocating a river, and adding riprap.

Riprap

A protective layer of loose stone added to slopes as a technique to mitigate mass wasting risk.

Tsunami Causes

The four main mechanisms that trigger tsunamis: earthquakes, volcanic eruptions, landslides, and impacts.

Convergent margins

Tectonic boundaries where most tsunamis occur, predominantly caused by seafloor displacement along thrust faults.

Tsunami destructive power

The destructive capacity of a tsunami that arises not from wave height, but from the momentum of a large mass of water combined with ultra-long wavelengths and wave periods.

Wave period

The time required for a wave to travel from crest to crest (or crust to crust).

Wave velocity

The horizontal speed at which a wave travels.

Wave length

The horizontal measurement or distance from peak to peak.

Tsunami wave period

The wave period characteristic of tsunamis, typically lasting from $10\,\text{minutes}$ to $2\,\text{hours}$, compared to $5\text{ to }20\,\text{seconds}$ for standard wind-caused waves and $5\text{ to }10\,\text{seconds}$ for storm waves.

Tsunami wavelength

The length of a tsunami wave from peak to peak, typically spanning $300\text{ to }600\,\text{mi}$, compared to $300\text{ to }600\,\text{ft}$ for wind-caused waves.

Tsunami wave speed

The velocity of a tsunami wave, which reaches $500\text{ to }600\,\text{mph}$ in deep water and decreases to $20\text{ to }30\,\text{mph}$ near the shore.

Shoaling

The process where tsunami waves encounter shallower water near shore, causing them to slow down to $20\text{ to }30\,\text{mph}$.

2004 Sumatra-Andaman Tsunami

A catastrophic earthquake-triggered tsunami event that resulted in widespread casualties and lots of deaths.

2011 Tohoku earthquake

A major earthquake in Japan that generated powerful tsunami waves, frequently leading to secondary hazards like fires.