A new study has found surprising grounds of expectant body of magma lurking beneath long - torpid volcano in the Cascade Range in the USA , with potentially huge implications for how geologists predict and monitor volcanic eruptions .

vent generally come in three flavor : active , inactive , and nonextant . Though it start out alittle complicatedin terms of what vent measure up for each category , active volcano are I with a recent volcanic eruption history , dormant volcanoes are ones that have not burst out in a long time but have the electric potential to do so in the future , while out volcanoes are no longer active or at endangerment of erupting .

It has long been believed that combat-ready volcanoes have gravid bodies beneath them , which are then largely ejected during eruption , and dissipate as the volcano move to being dormant . The new study , led by investigator at Cornell University , challenge this sentiment .

The squad looked beneath the Cascade Range , the mickle range spanning from the south of British Columbia , Canada , to North California , USA , mould it through the use of seismic undulation data . The Cascade Range stop an array of vent , differing in how dynamic they are , as well as size .

" The vent are the final result of the ho-hum slide of dense oceanic crust as it sinks beneath North America ( subduction ) , which releases body of water and melts overlying rock , " the US Geological Survey ( USGS)explains . " This rich volcanic zone hold the well - know watershed volcanoes and around 2,900 other have it off volcanic feature ranging from small cinder retinal cone to substantial shield volcano . "

Some volcanos , such as at Crater Lake in Oregon , have not been active in around4,800 years , while seven volcano in the Cascade Range have erupted since the beginning of the 18th Century . And yet , looking at the range as a whole , the team found that all of the volcanoes study had orotund bodies of magma beneath them , include the ones deemed dormant .

" disregardless of eruption relative frequency , we see declamatory magma bodies beneath many volcanoes , " Guanning Pang , the postdoctoral researcher who led the study , said in astatement . " It appears that these magma trunk exist beneath volcanoes over their whole lifespan , not just during an combat-ready DoS . "

The team points to the range of volcanoes at the range , from the infamously active Mount St Helens to the geologically quiet Crater Lake .

" Despite this diversity , we identify crustal magma bodies with comparable size beneath all these volcano at similar depth , " the team writes in their paper . " There appear to be long - lived , although not of necessity eruptible since the thawing fraction is downcast than the vital melt fraction of > 35 percent , magma body beneath most of these combat-ready vent . "

The squad believe that this patronise the idea that outbreak does not run out magma chambers , but relieves a footling pressure within them .

" For exercise , at Mount St Helens , the approximate volumes and melt fraction give upper - crustal melt volume of 8.5–171.0   km3 , compared with a magma - equivalent volcanic eruption volume of 0.5   km3for the 1980 eruption , or Holocene rates of clap of ~2   km3kyr–1 , " the team writes . " Such a magma body could then grow over a lifetime comparable to the 105–106yr distinctive lifetime of Cascade Range vent , being steady recharged from below and take fire only a pocket-size fraction of the available melt . "

While complicating the picture of volcanic natural process , the determination could facilitate lead to right predictions of volcanic bam .

" We used to call up that if we constitute a large amount of magma , that meant increased likelihood of eruption , " Pang bestow , " but now we are shifting perceptual experience that this is the service line situation . "

More study , as always , is call for .

" If we had a better general intellect of where magma was , we could do a much better occupation of targeting and optimise monitoring , " Geoffrey Abers , professor in geological sciences , said , adding that there are a " great many volcano that are sparsely monitored or have not been subject to intensive study . "

The team is planning further investigation into magma chambers beneath a miscellanea of volcanoes , including those in Alaska .

The study is published inNature Geoscience .