There are several things volcanoes do before they erupt: They exhibit anomalous
1) seismic activity,
2) ground deformation,
3) gas emissions
4) thermal emissions.
So scientists monitor changes in these characteristics and try to forecast the likelihood of an eruption. There are usually hours to day to weeks of warning for a volcano. The accuracy varies with volcano - sometimes a volcano shows all the signs of waking up, but then nothing happens. But for volcanoes that are closely monitored, the forecasts are very good and we are getting better at it all the time.
Unfortunately, earthquakes exhibit no known warning signs more than seconds before the quake hits.
A seismometer (or seismograph) is a sensor that detects the intensity of earthquakes caused by magma that is moving. It has been around for almost 2,000 years. The first seismograph was invented by a Chinese scientist. It looked like a large jar with dragon heads on every side. Each dragon had a metal ball in its mouth, and when an earthquake struck, one of the balls would drop into the open mouth of a toad sculpture below. By looking at which ball dropped, Heng (the inventor) said he could tell from which direction the earthquake came. (Actually he couldn't but it was a good guess!)
Luigi Palmieri invented a seismograph in 1856 while working near Italy's Mt. Vesuvias. He wanted a way to predict eruptions, and knew that tremors were usually felt before an eruption. The seismograph uses a pendulum to record movement of the ground below it. The squiggly lines recorded on paper by a seismograph are called a seismogram.
-- GPS(Global Positioning System) is a method to determine position of locations on Earth. It uses satellites that broadcast a signal and receivers that pick up and record the signal. GPS uses the relationship between velocity, distance, and time (velocity equals distance divided by time). With GPS, the velocity is the speed of light. Knowing the velocity and time (and the position of the satellite) allows the distance to be calculated. As magma moves up into a volcano the volcano swells and distances between points on the volcano increases (think of dots on a balloon) and the elevation at specific points increases. Such a change is a common occurrence prior to an eruption.
Volcanologists use these instruments to successfully predict eruptions which saves many lives. Scientists are trying to develop new ways to predict future eruptions.
1) seismic activity,
2) ground deformation,
3) gas emissions
4) thermal emissions.
So scientists monitor changes in these characteristics and try to forecast the likelihood of an eruption. There are usually hours to day to weeks of warning for a volcano. The accuracy varies with volcano - sometimes a volcano shows all the signs of waking up, but then nothing happens. But for volcanoes that are closely monitored, the forecasts are very good and we are getting better at it all the time.
Unfortunately, earthquakes exhibit no known warning signs more than seconds before the quake hits.
A seismometer (or seismograph) is a sensor that detects the intensity of earthquakes caused by magma that is moving. It has been around for almost 2,000 years. The first seismograph was invented by a Chinese scientist. It looked like a large jar with dragon heads on every side. Each dragon had a metal ball in its mouth, and when an earthquake struck, one of the balls would drop into the open mouth of a toad sculpture below. By looking at which ball dropped, Heng (the inventor) said he could tell from which direction the earthquake came. (Actually he couldn't but it was a good guess!)
Luigi Palmieri invented a seismograph in 1856 while working near Italy's Mt. Vesuvias. He wanted a way to predict eruptions, and knew that tremors were usually felt before an eruption. The seismograph uses a pendulum to record movement of the ground below it. The squiggly lines recorded on paper by a seismograph are called a seismogram.
-- Since magma gives off electric currents, electric meters are used tospot rising magma levels by measuring its electric current. Gravimeters can also detect flowing magma.
-- Scientists also take temperatures and gauge gas by using a Landsat satellite. The satellite uses infared sensors to detect temperatures and changes in volcanoes. Aircraft monitors the amount of gas released from the ground. An increase in sulfur dioxide and other gases usually means that there could be volcanic eruptions.
-- The tiltmeter is a sensor that uses a laser beam to find the rising or lowering of magma levels by measuring changes in ground elevation.-- GPS(Global Positioning System) is a method to determine position of locations on Earth. It uses satellites that broadcast a signal and receivers that pick up and record the signal. GPS uses the relationship between velocity, distance, and time (velocity equals distance divided by time). With GPS, the velocity is the speed of light. Knowing the velocity and time (and the position of the satellite) allows the distance to be calculated. As magma moves up into a volcano the volcano swells and distances between points on the volcano increases (think of dots on a balloon) and the elevation at specific points increases. Such a change is a common occurrence prior to an eruption.
Volcanologists use these instruments to successfully predict eruptions which saves many lives. Scientists are trying to develop new ways to predict future eruptions.
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