<a href="https://en.wikipedia.org/wiki/Lassen_Peak" id="mw8w" rel="mw:WikiLink" title="Lassen Peak">Lassen Peak</a> erupts with a powerful force, the only volcano besides <a href="https://en.wikipedia.org/wiki/Mount_St._Helens" id="mw9A" rel="mw:WikiLink" title="Mount St. Helens">Mount St. Helens</a> to erupt in the contiguous U.S. during the 20th century.