Main Question:To what extent can volcanoes be successfully predicted?
Strombolian eruptions result in giant pieces of rock being expelled through the volcano’s vent hole and often send lava arcing through the sky.
Hawaiian eruptions are less explosive, with lava flowing more slowly out of openings in the ground. Unlike the cinder cone shape of many volcanoes, these are much wider and less tall.
The Plinian eruption is the most violent type of eruption known, which shoots a giant cloud of ash and gases into the sky. In Plinian eruptions,a large portion or the whole volcano may collapse following the explosion. There are many other types of eruptions, including ones that occur under the sea.
Earthquakes and volcanoes occur primarily along plate boundaries; the frequency and type of events vary with the type of boundary. Plates interact with one another at boundaries in one of three ways: they diverge, converge, or slide past one another.
Plates are made up of two types of crust -- oceanic and continental; oceanic crust is thinner and denser that continental crust. A single plate can have both crusts.
Gravity and mantle convection are two driving forces for plate movements.
Various notorious eruptions of volcanoes in the past, such as Mount Pelée, Tambora, Krakatau and Pinatubo are examples of devastating impact of volcanic activity on nearby landscapes and communities. Many people got killed. Big numbers of people had to abandon their homes and land forever. The whole world's climate was changed for a while as result of eruption!
Effects of volcanic eruptions are mostly result of certain hazards. Volcanoes provide different hazards during an eruption. Each poses different risks affecting different areas. The most threatening hazards include:
Pyroclastic Flows
Nuées Ardentes
Volcanic Ashes
Lahars
Debris Avalanches, Landslides, Tsunamis
Blast
Lava
Types of Lava Flows
Gas
http://www.metrolic.com/the-mystery-of-the-stromboli-eruptions-107053/
http://answers.yourdictionary.com/science/why-do-volcanoes-erupt.html
http://www.volcano.si.edu/world/largeeruptions.cfm
Instruments used in predicting volcanoes:
Tiltmeter- used to measure small changes in the tilt of the earth's surface
Gravimeter
Richter Scale -measure the earth's activity and seismic waves from the earth's movement
seismometer(also called a seismograph)-to predict earthquakes
Several things volcanoes do before they erupt:
They exhibit anomalous
1) seismic activity, refers to the frequency, type and size of earthquakes experienced over a period of time. 2) ground deformation,
3) gas emissions, and
4) thermal emissions.
Sulfur emissions from the volcano vent and seismic activity are widely used to predict volcano activity.
Scientists monitor changes in these characteristics and try to forecast the likelihood of an eruption. There are usually hours to days or weeks of warning for a volcano. The accuracy varies- sometimes a volcano shows all signs of waking up, but then nothing happens.However,closely monitored volcanoes have very good forecasts and we are getting better at it.
Scientific instruments attempt to detect early signs,and behavior of birds and animals may give warning of a shock, but none are currently foolproof.
Hazard Mapping and Satellite Monitoring could be used so we can tell exactly when the volcano will erupt. Some countries could also use barrier walls to penetrate the lava flow and use diversionary lava channels.
Hazard Mapping is knowing the phenomenon and making it known to residents.
providing with information on range of possible damage and disaster prevention activities.
Resident-educating type: This map has the main objective to inform the residents living within the damage forecast area of the risk of danger.Information on areas of danger or places of safety and the basic knowledge on disaster prevention are given to residents. Therefore, it is important such information should be understood properly.
Administrative information type: This type is used as basic materials the administrative agencies utilize to provide disaster prevention services. These hazard maps can be used to establish a warning system and evacuation system, as well as evidence for land use regulations. They may also be used in preventive works.
http://en.wikipedia.org/wiki/Earthquake
