EQ2: Why do some tectonic hazards develop into disasters? GapFill

 ProblemsHazardsSolutionsRisks are the potential threat to people’s lives and belongings.  They can kill and injure people, destroy homes and belongings, and have severe economic and environmental consequences.  These potential results are risk.  When a hazard is realised, then that is  a disasteran occurrencea riskan event.

 NaturalArtificialAnthropogenicShort-term hazards occur without human control.  We do our best to predict when they will occur, but it’s very difficult, and they usually give very little warning.  We can’t stop them from happening so we need to adapt the way we live to minimise their effects on us.  We can also try to directly mitigate their effects, but only to a degree.

 VulnerabilityRiskPlanningManagement is how much a person is likely to be affected by a hazard, influenced by how effectively they can prepare for a hazard and cope after a disaster.

The level of  populationdeath ratedevelopmentbirth rate or the economy affects vulnerability – the more developed a country, the more choice its citizens might have about where they live, and the higher the level of development, the greater the chance of being protected from hazard, e.g. better planning, warning systems and structures in place.

The effects of a hazard differ based on the location and the influence of human and physical geography.   PrimaryDisasterTertiarySecondary effects occur instantly and are directly caused by the disaster.   SecondaryHumanTertiaryPrimary effects occur as a result of the primary effects in the hours, days and weeks after a disaster.

Hazards occur on different scales.  The effects from some can be felt throughout the world, while others may affect only a local area.   MagnitudePrimaryLogarithmicMapping is the size or scale of the event – often classified on a scale.   LogarithmicMagnitudeSecondaryDistribution is the area affected by the hazard.

We use different scales to measure earthquakes.  We once used the Richter scale (developed a long time ago and specific to the crust found below California).  This used  a lineara logarithmican infinitean open scale measuring how much energy was released, and data was provided by a  telephoneseismometersatelliteprinter.  Nowadays, we usually use its successor, the moment magnitude scale.

Another way of classifying an earthquake is based on its effects.  This is the  MercalliMeridianMerchantMoment scale, and the later modified scale.  The scale goes from I to XII, and each notch has a description and an assessment of the ground-shaking.

One scale we use to measure a volcano’s eruption is the volcanic  explosivityexplanatoryeffectivenesseffusive index (VEI).  This is a logarithmic scale that uses three indicators – the amount of material ejected, the height into the atmosphere that the material reaches and the duration of the eruption.