Engineering Geology

Earth Hazazrds

Infastructure

Waste

Earthquakes

Volcanic Eruptions

Tsunamis

Landslides

Hazards

Building collapse

Ground Liquefaction

Fires

Landslides

soil substantially loses strength and stiffness

Due to an applied stress such as shaking during an earthquake

Concentrated on plate boundaries

Generated by submarine (below sea) Earthquakes

Initiated by Earthquakes

Initiated by Volcanic eruptions

Initiated by Slope failure

Generated by volcanic island collapse

Generated by meteorite impacts into the sea

Generated by landslides into the sea

Hazards

Lava flows

ash fall

Pyroclastic flow

Lahars

Risk reduction methods

Minimum standards for reinforced concrete

Safety glass to replace conventional glass in skyscrapers

Retrofitting foundations with rubber dampeners

Smart values to turn off oil/gas supplies when Earthqukes occur

Use of bolts to pin walls to floors

Reduce chance of 'pancaking'

collapse occurs from the top-down

Upper floors collapse down onto lower ones, causing collapse

Fasteing of major appliances to walls to prevent movement

E.g. fridges, TVs

Deep foundations into solid bedrock

New building's with lower center of gravity

Not affected by liquefaction

Avoid building on areas prone to liquefaction during Earthquakes

Computer-controlled weights on the top of skyscrapers to counter any swaying caused by a seismic event

Floors able to slide horizontally on muli-storey buildings

Through the use of a rack and pinion device and teflon (non-stick) coated materials on the base/top of floors

Avoid building on:

Reclaimed land

marshes

Old lake beds

River floodplains

Reinforce weak points in infrastructure to ensure they are Earthquake resistant

Tunnels

Bridges

Flyovers

Freeways/Motorways

Risk reduction methods

Implementing building restrictions in areas prone to eruptions

Risk reduction methods

Buildings on stilts in areas prone to tsunamis

Allow water to flow underneath

Planting of mangroves in coastal areas prone to tsunami

Mangroves absorb the force of the waves

Prediction of Hazards

Measuring Ground deformation

using tiltmeters

Measure minute changes the angle of the Earth's surface

ground increasing in tilt/bulging over time

Magma moving towards surface

land fails

  1. major Earthquake
  1. volcanic eruption

Prediction of Hazards

Groundwater changes

Monitor in Boreholes:

Water chemistry

Water levels

Temperatures

Increased Temp.'s , increased dissolved sulphur dioxide, increased carbon dioxide

Falling water levels, increase in dissolved radon gas

Sometimes occur before major seismic event

Magma moving towards surface

May lead to volcanic eruption

Gas emissions

Correlation spectrometers (COSPEC) around active volcanoes

rapid carbon dioxide and Sulphur dioxide emission increase just (24-48hr) before eruptions

Hazard Interval Patterns (Seismic Gaps)

Seismic Gaps in time

Long time since Earthquake at a certain part of the Boundary (compared with other segments along the same boundary/structure)

Seismic gap in space

Long time since Earthquake around/near to a certain part/segment of the Boundary (compared with other segments along the same boundary/structure)

(At Segments of an active fault known to produce significant earthquakes)

Detailed record of past seismic events

With dates

Can be used to calculate an average resurgence interval for a seismic event over a certain magnitude

With locations

Areas that haven't expericnced seismic events for a long time/at all are more likely to have the next seismic event

Seismic event more likely

Risk reduction methods

Investment in emergency services and rescue equipment

Bulldozers, JCBs, cranes, fire engines

Doctors, paramedics, hospitals

heat-seeking equipment, sniffer dogs

Factors affecting level of risk (to hazards)

Population density

Increased pop. density = increased casualties

Technology

Aseismic desgn

Early warning systems

Rapid response emergency services

Land use planning

High risk areas

Parks, Golf couses, ect.

Low risk areas

Hospitals, schools, ect.

Intermediate risk areas

Houses, commerical

Communication

lack of PCs, broadband, political will

Warnings poorly communicated

Increased casualties

Decreased casualties

In MEDC's and HEDC's

In LEDC's

(Least/Less Economically Developed Countries)

Causalities higher (per pop.) in LEDC's

as they lack money to invest on Disaster prevention

More pressing matters occupy resources (e.g. shelter, education, health care)

Warning + Evacuation schemes

Earthquake drills

Clear Evacuation routes

Early warning

Decreased casualties

Factors that affect waste disposal

Waste type

Domestic

Hazardous

Medical waste, industrial waste, radioactive waste

Household waste, garden waste, ect.

Waste that needs special disposal

Permability

Impermeable rock types

Permeable rock types

Site must be made impermeable through Engineering

Clay linings

Artificial geomembranes

(Type of textile sheet to prevent seepage from waste disposal site)

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preventing contamination

Toxic Leachate is collected in a sump and removed from landfill for treatment

Leechate

r the liquid pollution that seeps through a landfill's waste pile when it rains or snows

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(landfill)

monitor local rivers, ponds, wells and springs

ensure that water quality is
of an acceptable and safe standard

Ensure not contaminated

Toxic waste storage

in sealed drums

underground in impermeable rocks

(e.g. as in disused salt mines)

at the surface in secure repositories

Restoring contaminated ground

removing the soil and replacing it with a cleaner alternative

Employing bioremediation using microbes
and/or plants to extract the toxic materials from the ground

Remove/harvest

treat so that they are safe

bioremediation

process that uses mainly microorganisms, plants, or microbial or plant enzymes to detoxify contaminants in the soil and other environments

Geological factors affect the siting of engineering projects

Such as:

Dams

Reservoirs

Cuttings

Tunnels

Rock fact cut out for road, rail, ect.

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Stability of the rock

Mechanically strong

Mechanically weak

Can support steep slopes

Unable to support steep slopes

collapse/slump after periods of high rainfall

e.g. clay, mudstone, shale

e.g. limestone, sandstone, granite

Permeability of the rock

Permeable

Absorbs water

Increases in mass

increases pore water pressure

the pressure experienced by water trapped in pores

slope failure

Presence of faults + joints

Faults and joins common

Fault reactivaton may occur

Fault may reopen due to stress, think 'structures' unit

Expensive engineering solutions to re-stabilize area

Dip (direction + angle) of strata

Strata dips down towards excavation

Expensive slope stabilization

Strata dips down away from excavation

Naturally stable

Methods to overcome geological factors/problems

Rock bolts

shockcrete

Gabion baskets

Slope re-profiling

Drainage

Or slope failure

slope failure

(slope collapse)