Natural Hazards

A National Threat

Presidential Disaster Declarations in the United States and Territories by county from 1965–2003 reflect the broad geographic distribution and human impacts of earthquakes, floods, hurricanes, landslides, tsunamis, volcanoes and wildfires. (Map not to Scale. Source: FEMA)

National Natural Hazard Facts . . . Over 75 percent of declared Federal disasters are related to floods.

More than half of the U.S. population lives within 50 miles of a coast. Many of these areas, especially the Atlantic and Gulf coasts, will be in the direct path of future hurricanes.

Landslides affect every State, causing $3.5 billion dollars annually in damages and between 25 and 50 deaths.

The United States faces significant tsunami threats to the West Coast, Hawaii, Alaska, and island territories in the Caribbean and the Pacific.

The United States has 169 active volcanoes capable of producing a wide range of hazards that threaten people and infrastructure on the ground as well as aircraft in flight.

In 2004, wildfires burned more than 8 million acres in 40 States.

http://pubs.usgs.gov/fs/2007/3009/2007-3009.pdf

Why does California have so many hazards?

The answers lie in the geography of the state: its geology and climate, and also in the way humans have used and misused the landscape and resources.

Introduction to Natural Hazards What is a “Geohazard”?

Earth processes (involving the lithosphere, hydrosphere & atmosphere) that, upon interaction with human activity, cause loss of life and property

It is important to understand the human element without it, there would be no hazard because of it, the science of geohazards becomes more

important every year mitigation: reduction/prevention

geo-process

humanprocess

Hazardousconditionor result

The Earth’s population is increasing more people living in hazard-prone areas populations are becoming hyper-concentrated consumption of resources examples:

today there are 6 billion people on Earth ( ~ 50% live in cities) by 2025, there will be ~8 billion people (~ 66% in cities) of these cities, 40% are coastal

prone to severe storm and tsunami damage and a large majority lie in areas subject to other geohazards

(for example volcanoes and earthquakes)

Why is the human element so critical?

•CANNOT stop the geologic processes•CANNOT stop the population growth/expansion

•Therefore, we must try to reduce (mitigate) the hazards through:

•scientific study•population education•changes in engineering/building practices•management plans and hazard response scenarios

Name some types of Natural Hazards

Volcanoes, floods, earthquakes, landslides, tsunamis, wildfires, etc. can act adversely on human processes can occur:

without warning (e.g. earthquakes) with warnings (precursors) (e.g. satellite

monitoring of cyclone tracks, or the presence of ground deformation at a volcano before an eruption)

To help mitigate the hazard we need to know: Frequency vs. Magnitude

F: how often a given event occurs in a certain region

M: how powerful (amount of energy released) an event is

for example, high M hazards happen with low F, but are much more destructive

Scope S: area affected by a given hazard

local: landslides, floods, earthquakes, fire … regional: tsunamis, volcanoes, larger earthquakes,

cyclones … global: large volcanoes, global warming, meteorite

impacts …

Practical Exercise 1.

Impact of Environmental Disasters