Mount St. Helens, the volcano in Western Washington state located approximately 70 miles northeast of Portland, Oregon, is showing signs of extended magma build-up and seismic activity, but there's no evidence of an eruption soon.

Scientists with the United States Geologic Survey's Cascades Volcano Observatory have said in a statement posted on its official Website that a magma reservoir located an estimated four to six miles under the surface has been steadily re-pressurizing since the 8,363-foot volcano vented steam from 2004 to 2008.

Scientists believe the mountain's natural reservoir of fresh molten rock has been recharging Mount St. Helens, which last erupted in 1980.

However, researchers have only recently been able to confirm that the volume of magma is increasing, Carolyn Driedger, a USGS spokeswoman, told NBC News.

"The magma could be at current levels for another 100 years before any eruption," Driedger said.

The eruption of Mount St. Helens on May 18, 1980, spewed a giant plume of volcanic ash into the sky, sent destructive flows of pyroclastic materials down local rivers, toppled a forest and killed 57 people.

Here's the full statement from the Cascades Volcano Observatory :

"Activity Update: All volcanoes in the Cascade Range of Oregon and Washington are at normal levels of background seismicity. These include Mount Baker, Glacier Peak, Mount Rainier, Mount St. Helens, and Mount Adams in Washington State; and Mount Hood, Mount Jefferson, Three Sisters, Newberry, and Crater Lake in Oregon.

"Recent Observations: All the volcanoes were relatively quiet seismically and exhibited only typical background activity. The stage on regional rivers, which had been elevated owing to storms, has been slowly but steadily declining. The Cascades Volcano Observatory issued an information statement on 30 April 2014 summarizing geodetic- and seismological evidence for re-pressurization of the magma reservoir beneath Mount St. Helens since 2008. There is no evidence to suggest that this re-pressurization portends an imminent eruption."