Scientists can't pinpoint exactly when Mount St. Helens will next erupt, but perhaps they can hazard a more educated guess after gathering data at the site this past weekend.

An international team of around 75 geophysicists planned to drill 23 holes into the mountain over the weekend. The scheme to create seismic waves with the holes is part of a larger project that is essentially like taking an ultrasound and CAT scan of the volcano, the Associated Press reported.

"Mount St. Helens and other volcanoes in the Cascade Range threaten urban centers from Vancouver to Portland, and we'd like to better understand their inner workings in order to better predict when they may erupt and how severe those eruptions are likely to be," said lead researcher Alan Levander of Houston's Rice University, as quoted by the AP.

The scientists also planned to map around 3,500 seismic sensors around Mount St. Helens while they drilled holes to result in small-scale explosions similar to a magnitude 2 earthquake.

In other volcano-related news, researchers from four states have used seismic imaging to study Mount Rainier, publishing their findings this week in the journal Science.

The data they collected shows how magma builds underneath Mount Rainier for future eruptions, according to geophysicist Phil Wannamaker of the University of Utah.

Wannamaker put Mount Rainier's magma reserve at about 5 to 10 miles deep and 5 to 10 miles wide from east to west, the AP reported via Seattlepi.com.

"But it does not provide any information on the timing of future eruptions from Mount Rainier or other Cascade Range volcanoes," he said.

The U.S. Geological Survey said in a May report that building magma is normal for an active volcano and an eruption isn't expected for Mount St. Helens any time soon.

Scientists have been monitoring the volcano, which has been building magma 2.5 to 5 miles below the surface, since it last erupted from 2004 to 2008, CBS News reported at the time.

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