There are enough supervolcanoes on Earth to wipe out much ofthe planet and they may "wake up" much sooner than wethought. Supervolcanoes explode with a force that isthousands of times that of a normal volcanic eruption.Earthquake experts once thought it would take hundreds ofthousands of years for the reservoirs of molton rock (calledmagma) lying beneath a supervolcano to build up enoughpressure to cause an eruption, but a new study shows thatthe time between eruptions can actually be only tens ofthousands of years, meaning many of them are long overdue.
The Journal of Petrology reports that an eruption from asupervolcano can be strong enough to cause change theworld's climate enough to cause a mass extinction, due tothe large amounts of ash that would be thrown up into theatmosphere. One of these temporarily dormant volcanoes liesbeneath Yellowstone National Park in Wyoming. The last timeit erupted, over 600,000 thousand years ago, half the NorthAmerican continent was covered in volcanic ash.
Exactly how long does it take for the enough magma pressureto build up beneath a supervolcano to cause it to erupt? Theanswer: around 40,000 years, which may seem like a long timeto us but is a blink of the eye in geologic time. A supereruption is five to 10 times more likely to happen than anasteroid impact. Scientists now know that the magmareservoir underneath the Yellowstone supervolcano has risen19 inches, which is evidence that pressure is building.
Paul Rincon writes in BBC news that geologist Stephen Selfwants to set up an emergency contingency plan to prepare forthe eruption of a supervolcano. The super-eruption thatstruck Sumatra 74,000 years ago may have taken the humanrace to the edge of extinction by blacking out the sun andcausing a "volcanic winter." DNA studies show that thenumber of humans on the Earth dropped to about 10,000,probably as a result of climate change.
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