Geophysical Hazards

Option D 1: Geophysical systems -

How hazard risk is a function of spatial interactions between different human and physical processes

The varying spatial scale of the processes and challenges associated with different kinds of geophysical event and their aftermaths

Different perspectives on how geophysical hazard risks should be managed

How spatial patterns of risk and vulnerability can be represented graphically

1. Geophysical systems

How geological processes give rise to geophysical events of differing type and magnitude

Some vocabulary:

Disaster: A major hazard event that causes widespread disruption to a community or region that the affected community is unable to deal with adequately without outside help.
Hazard: A threat (whether natural or human) that has the potential to cause loss of life, injury, property damage, socio-economic disruption or environmental degradation.
Hazard event: The occurrence (realization) of a hazard, the effects of which change demographic, economic and/or environmental conditions.
Risk: The probability of a hazard event causing harmful consequences (expected losses in terms of deaths, injuries, property damage, economy and environment).
Vulnerability: The susceptibility of a community to a hazard or to the impacts of a hazard event.

Mechanisms of plate movement including internal heating, convection currents, plumes, subduction and rifting at plate margins

Tectonics

Draw labeled diagrams explaining the following

The different layers of the earth
Seafloor spreading
Convection currents and isostacy
Subduction zones

Characteristics of earthquakes

depth of focus (hypocenter), epicentre and wave types (P, S, L, R)

caused by varying types of plate margin movement and human triggers (dam building, resource extraction); and associated secondary hazards (tsunami, landslides, liquefaction, transverse faults)

Ground shaking is the primary hazard. Everything else is a secondary hazard, including faults in the ground.

IB 12 - Earthquakes

Human triggers: Dam building and resource extraction

Secondary Hazards

tsunami, landslides, liquefaction, transverse faults

Watch the video at the top of this page

Exercise (suggested pages from Bishop)

1. Using visuals, explain the key principles of the Richter scale (43)

2. Draw a labeled diagram explaining. Include a known, recent example of hazard event.

ground shaking (44)
liquefaction (46)
tsunamis (84)
landslides caused by earthquakes (p. 46)
fires caused by earthquakes

Characteristics of volcanoes (shield, composite and cinder) formed by varying types of volcanic eruption; and associated secondary hazards (pyroclastic flows, lahars, landslides)

First watch the videos below:

Secondary Hazards

Lahars: Also called a volcanic mudflow or debris flow. A mixture of water and volcanic debris that moves rapidly downstream. Consistency can range from that of muddy dishwater to that of wet cement, depending on the ratio of water to debris. They form in a variety of ways, chiefly by the rapid melting of snow and ice by pyroclastic flows, intense rainfall on loose volcanic rock deposits, breakout of a lake dammed by volcanic deposits, and as a consequence of debris avalanches. (source)

Pyroclastic Flow: A hot (typically >800 °C), chaotic mixture of rock fragments, gas, and ash that travels rapidly (tens of meters per second) away from a volcanic vent or collapsing flow front. (source)