Mount Rainier is behaving about as it has over the last half-million years, so all evidence suggests that the volcano will continue to erupt, grow, and collapse.

What would happen if Mount Rainier erupted?

It would be hot, and it would melt the ice and snow. And tumble over cliffs. “The lava flows encounter those very steep slopes and make avalanches of hot rocks and gas that are hurtling down the mountain maybe 100 miles per hour or so,” Driedger says.

Is Mt Rainier going to erupt again?

Over the past half million years, Mount Rainier has erupted again and again, alternating between quiet lava-producing eruptions and explosive debris-producing eruptions. ... While Mount Rainier's last eruptive period was about 1,000 years ago, Mount Rainier is considered an active volcano and will have future eruptions.