seismic hazards

Seite 1

Seismic Hazards

Nature and Distribution

Slow build-up of stress in crust

Pressure released

Causes ground to shake

Focus – in crust

Epicentre – point on earth’s surface

Depth

Deep focus – 300700 km

Intermediate focus – 70300 km

Shallow focus – 070 km – most damaging

Conservative boundary

Distribution

Occur at plate boundaries

Conservative

Anomalies

Intraplate deformation

Human activity

Magnitude

Richter scale

110

Logarithmic

Mercalli scale

112

Intensity and impact

Based on human observations

Frequency

Seismic records

Seismometer – detects shaking of ground

Historical records

Effects of seismic events

Primary impacts

Immediate

Ground rupture

Ground shakings

Secondary impacts

Landslides/avalanches

In glaciated areas

Tsunami

Fires

Building collapse

Soil liquefaction

Tsunamis

Giant sea wave

Shallow focus (underwater EQ)

Long wavelength (100km+)

Travel up to 700km/h

As they reach land rapidly increase in height (over 25m tall)

Effects

Disease

Depend on

Waring systems

Coastal geography

Population density

Distance travelled

Infrastructure destroyed

People injured by debris

Frowning

Wash coastal structures inland

Managing seismic hazards

Prediction

Frequency

Random

Radon gas

Animals

Magnetic fields

Plate boundaries

Prevention

Impossible

Protection

Insurance

Aid

Land-use planning

Tsunami protection

Hazard resistant structures

Education

Fire prevention

Emergency services