Planet Earth - Natural Hazards and Risk Management

Flashcards about natural hazards and risk management, focusing on earthquakes, coastal erosion, floods, karsts, droughts, desertification, and volcanoes.

What are some hazards associated with earthquakes?

Faults, Tsunamis, Aftershocks, Liquefaction, Landslides

What is the Elastic Rebound Theory?

Energy can be stored in elastically deformed rock; earthquakes release that stored energy through faults

What is an active fault?

Faults actually accumulating slip (relative movement).

What is the focus of an earthquake?

The point on the fault where break (rupture) first occurs in the subsurface.

What is the epicenter of an earthquake?

The point at the surface directly above the focus.

What are the two main types of earthquake waves?

Body waves and Surface waves

What are the types of body waves?

Primary wave (P-wave) and Secondary wave (S-wave)

What are the types of surface waves?

Love waves and Rayleigh waves

What is the difference between the Richter scale and the Mercalli scale?

Richter scale measures the energy of the earthquake physically while the Mercalli scale measures the effect of the earthquake on people and buildings

What is a tsunami?

A series of huge waves caused by earthquakes.

What is an aftershock?

A smaller earthquake following the major bigger earthquake.

What is liquefaction?

The escape of water from an aquifer to the surface because of shaking the earth’s surface in an earthquake.

What is a landslide?

Mass wasting from a slope due to seismic activities, water or gravity effects.

What are the three types of structures may be built on or near coasts to minimize coastal erosion?

Seawalls, Breakwaters, Groins

What is the main aim of building a seawall?

To minimize the energy of the sea waves and provide a protective cover for the more easily eroded coastal sediments and rocks.

What is the aim of a breakwater?

To absorb the energy of waves and therefore protect the coast.

What is the role of building a groin?

To prevent longshore currents from eroding the beach sand.

What are some techniques used to minimize the effects of floods?

Building levees, diversion canals and dams.

What are karsts?

Cavities usually formed after dissolution caused by chemical weathering in limestone.

How to reduce the risks of karsts?

Preliminary site evaluation using geophysical methods could assess in construction site selection to avoid karsts risk areas.

What is a drought?

An extended period of months or years when a region notes a deficiency in its water supply.

What is desertification?

The conversion of crop productive land to desert.

What controls the violence of volcanic eruptions?

The viscosity of the magma.

What are the three classes of volcanoes?

Shield volcanoes, Strato-volcanoes (or composite), Cinder cone volcanoes