8/3/2019 Agricultural Benefits

http://slidepdf.com/reader/full/agricultural-benefits 1/7

 

1

Agricultural benefits - After a volcanoic eruption the burning lava can turn

into the some of the richest soil in the world. Some early civilizations grew

their food (farmed) in the rich volcanic soil.

Energy source benefits - Geothermal energy is a useful way to make

electricity. With a ready supply of water and and a steadt source of heat, steam

Governments all over the world must prepare to give

adequate warning of potential disaster and be ready to

organize speedy evacuation if need be. This means that

resources such as television, radio, and a sufficient road

network be available. For many places around the world,

however, this is not the case. 

This can be especially true of many communities living closeto volcanoes. Many poor countries do not have the resources

to notify and evacuate people. Densely populated areas have

to deal with being able to efficiently move large numbers of

people as quickly as possible. 

Since different types of volcanoes can produce different

forms of disaster damage, it is important that governments

and community planners be knowledgeable about the type of

volcano each area must deal with. Each community then

should plan ahead as much as possible in order to be ready

for a possible eruption. It is important that all residents of

these areas take the time to find out about their

community's disaster preparation plans. In the United

States, county and/or state governments all have civil

defense agencies which help coordinate disaster plans.

Each community must know the potential eruption risk of thevolcano in their area. Just because a volcano has not

erupted for hundreds of years does not mean that the

volcano is no longer dangerous. Numerous volcanoes along the

Cascade Mountains in the Pacific Northwest have the

potential to erupt explosively. One of these volcanoes did

 just that in 1980, with the destructive eruption of Mt. St.

Helens. Worried city planners in the densely populated area

of Seattle, Washington are currently involved in seriouspreparations for the potential eruption of Mt. Rainier, which

last erupted in 1882. Miles upon miles of homes have been

built in the path of projected pyroclastic flows. 

8/3/2019 Agricultural Benefits

http://slidepdf.com/reader/full/agricultural-benefits 2/7

 

2

For the most part, the people of Hawaii have to deal with

volcanic eruptions that produce slow-moving lava, which

allows time for people to safely evacuate. However, many

homes and historic landmarks have been lost to theseunstoppable fiery flows. Planners living in the shadows of

Italy's Mt. Etna have met with some success in building lava

barriers to protect towns but such efforts have not yet

been found possible for the communities of Hawaii. 

It is known that Hawaii's currently active volcano of Kilauea

does have a history of explosive events. It seems to erupt

once every 300 years. The day will come when it will happen

again. The Hawaii Volcano Observatory and Hawaii Volcano

National Park's Jaggar Museum sit right on the potential

explosion area. 

It is expected that the currently inactive volcano of Maunea

Loa, which last erupted in 1984 and threatened the city of

Hilo, will erupt again. Hualalai Volcano last erupted in 1800

and is still considered potentially active. Mauna Kea, last

active some 4,000 years ago, may yet give one final blowbefore completely dying. 

Haleakala, on the island of Maui, last erupted in 1790 and is

now entering a period of possible eruption. 

Fortunately, scientists from all over the world have come to

Hawaii to study its volcanoes. The people of Hawaii have

benefited from the extensive knowledge that has been

learned and have used this to develop their community

disaster plans. New instruments for measuring a wider

variety of eruption indicators have been developed and are in

place. The work done in Hawaii made it possible to give a

better warning for the 1980 Mt. St. Helens eruption. 

The people of Hawaii can rely on their civil defense agencies

and the state's emergency broadcast system to keep them

Remember, being well-informed means being well-prepared. 

8/3/2019 Agricultural Benefits

http://slidepdf.com/reader/full/agricultural-benefits 3/7

8/3/2019 Agricultural Benefits

http://slidepdf.com/reader/full/agricultural-benefits 4/7

 

4

resources, and scenic beauty. But volcanoes can be very dangerous. Where

can a person go to be safe from an erupting volcano? What types of volcanic

hazards might they face? These questions are difficult to answer because

there are many types of volcanic eruptions which produce different types of 

volcanic hazards. 

Types of Volcanic Eruptions 

When Mount St. Helens erupted on May 18, 1980, red hot lava did 

not spew out of the volcano and pour down its flanks. This

 perception of a volcanic eruption is a common one and is

 probably due in part to pictures seen on television or in books of 

the beautiful lava flows and lava fountains in Hawai'i. The type of 

eruptions in Hawai'i are known as hawaiian volcanism and are

 far less dangerous than the eruptions produced by Mount St.Helens. It is important to know what type of an eruption a

volcano is most likely to produce so that the types of hazards

 produced by such an eruption can be identified. Knowledge of 

these types of hazards, will help determine where a person would 

need to go to be safe during a volcanic eruption.

Volcanic eruptions can be placed into two general categories: those that

are explosive, such as at Mount St. Helens, and those that are effusive,

such as in Hawai'i. The most active volcano in the world, KilaueaVolcano on the big island of Hawai'i, is generally a nonexplosive

volcano (though there have been occasions when it erupted explosively).

Eruptions from it normally result in gently flowing lava flows, spatter

cones, and lava fountains. Another type of nonexplosive volcanism

is flood basalts. Lava flows from this type of eruption are extruded from

fissures and cover vast areas. These nonexplosive eruptions are the least

dangerous type of volcanic eruption since people rarely get killed by

them (Francis, 1993). However, they are devastating and may have

global consequences. 

8/3/2019 Agricultural Benefits

http://slidepdf.com/reader/full/agricultural-benefits 5/7

 

5

Many eruptions are explosive in nature. They produce

 fragmental rocks from erupting lava and surrounding country 

rock. Some eruptions are highly explosive and produce fine

volcanic ash that rises many kilometers into the atmosphere in

enormous eruption columns. Explosive activity also causes

widespread ash fall, pyroclastic flows, debris avalanches,landslides, pyroclastic surges, and lahars. Explosivity is usually 

the result of gases expanding within a viscous lava. Another 

mechanism for explosions at volcanoes occurs when surface

water or ground water enters a magma chamber. These

eruptions are likely when a volcano occurs in a wet area or in the

 sea.

What is a Volcanic Hazard?

A volcanic hazard refers to any potentially dangerous volcanic process (e.g.

lava flows, pyroclastic flows, ash). A volcanic risk  is any potential loss or

damage as a result of the volcanic hazard that might be incurred by persons,

property, etc. or which negatively impacts the productive

capacity/sustainability of a population. Risk not only includes the potential

monetary and human losses, but also includes a population's vulnerability. The

definitions of hazard and risk are not well-defined.

8/3/2019 Agricultural Benefits

http://slidepdf.com/reader/full/agricultural-benefits 6/7

 

6

Tilling and Lipman (1993) estimate that 500 million people will 

be at risk from volcanic hazards by the year 2000. In the past 500

 years, over 200,000 people have lost their lives due to volcanic 

eruptions (Tilling, 1980). An average of 845 people died each

 year between 1900 and 1986 from volcanic hazards. The number 

of deaths for these years is far greater than the number of deaths for previous centuries (Tilling, 1991). The reason behind this

increase is not due to increased volcanism, but due, instead, to an

increase in the amount of people populating the flanks of active

volcanoes and valley areas near those volcanoes (Tilling, 1991

and Hall, 1991).

Types of Volcanic HazardsThe following is a list of volcanic hazards. Click on the one that 

 you are interested in learning about.

  Volcanic Earthquakes 

 

Directed Blast  

  Tephra 

 

Volcanic Gases 

  Lava Flows 

  Debris Avalanches, Landslides, and Tsunamis 

 

Pyroclastic Surge 

 

Pyroclastic Flows 

 

Lahars 

Hazards Prevention

In recent years, with the eruptions of Mount St. Helens and Mount 

Pinatubo many advances have been made in the study of 

volcanoes particularily in eruption prediction. The problem with

volcanoes is that, though there may be similarities between

volcanoes, every volcano behaves differently and has its own set 

of hazards. That is why it's important for scientists to study and 

monitor volcanoes. Many active volcanoes near populated areas

have not been sufficiently studied to assess risk.

8/3/2019 Agricultural Benefits

http://slidepdf.com/reader/full/agricultural-benefits 7/7

 

7

When scientists study volcanoes, they map past volcanic deposits

and use satellites to look at volcanic features, ash clouds, and gas

emissions. They also monitor seismic activity, ground 

deformation, and geomagnetic, gravimetric, and geoelectrical 

and thermal changes at a volcano. They study and monitor 

volcanic gases and monitor the temperature, flow rate, sediment 

transport, and water level of streams and lakes near the volcano.

By studying volcanic deposits, scientists can produce hazard 

maps. These maps indicate the types of hazards that can be

expected in a given area the next time a volcano erupts. Dating of 

these volcanic deposits helps determine how often an eruption

may occur and the probability of an eruption each year.

Monitoring of a volcano over long periods of time will indicate

changes in the volcano before it erupts. These changes can help

in predicting when an eruption may occur.

 A Few Final Remarks...

The main reason scientists study and monitor volcanoes is so

that those living near active volcanoes can be aware of the

hazards produced by volcanoes. This awareness will hopefully 

 prevent loss of life and property when an eruption occurs. It is

important that scientists communicate with local government 

officials and the general public about hazards produced by the

volcanoes in their area. This interaction and the developement of 

an emergency plan with established lines of communication will 

hopefully save lives and encourage better land use planning.