Mount St. Helens, a prominent peak in the Cascade Range of Washington, is widely recognized for its dramatic 1980 eruption. This cataclysmic event reshaped the landscape and captured global attention, leaving a lasting impression. Many people continue to wonder if this famous volcano remains a threat or if its active days are behind it. The straightforward answer is that Mount St. Helens is indeed still considered an active volcano, continuously observed for any signs of renewed unrest.
Understanding Volcanic Activity
Understanding a volcano’s status requires a grasp of volcanological terms, as “active” does not always mean erupting. An “active” volcano is one that has erupted in recent geological history (typically within the last 10,000 years) or shows clear potential to erupt again. This classification means the internal magmatic and tectonic processes for an eruption are still present and ongoing beneath the surface. In contrast, a “dormant” volcano has not erupted for a significant period but could still become active, while an “extinct” volcano is one scientists believe will not erupt again due to a permanent lack of magma supply.
A Brief History of Mount St. Helens’ Eruptions
Mount St. Helens has a long and dynamic eruptive history, with activity dating back approximately 40,000 years. It stands as the most active volcano in the Cascade Range during the Holocene epoch, which covers the last 10,000 years. The volcano’s most impactful modern event was the May 18, 1980, eruption, which dramatically altered its summit and surrounding environment. Following this major blast, Mount St. Helens exhibited further activity between 1980 and 1986, including the growth of a new lava dome within the crater. Another significant period of renewed activity occurred from 2004 to 2008, characterized by continuous magma extrusion that built a new lava dome, along with steam and ash emissions.
Mount St. Helens Today: Monitoring and Current Signs
Mount St. Helens is closely monitored by scientists to track its subsurface activity and detect changes. The U.S. Geological Survey (USGS) and the Pacific Northwest Seismic Network (PNSN) use a comprehensive network of instruments:
- Seismographs are deployed to detect and precisely locate earthquakes, which indicate magma movement, fracturing of rock, or stress changes.
- Continuous GPS stations precisely measure ground deformation, revealing subtle landscape changes as magma accumulates beneath the surface or as pressure builds.
- Gas sensors are employed to detect and analyze volcanic gas emissions, such as sulfur dioxide and carbon dioxide, providing clues about the depth and activity of the magma chamber.
- Satellite imagery also plays a significant role, offering a broad view of changes in the volcano’s surface, detecting thermal anomalies, and tracking ash plumes.
While Mount St. Helens is not currently erupting, it exhibits ongoing signs of activity, including small, shallow earthquakes and subtle ground changes. Since mid-July 2023, over 400 small earthquakes have been recorded, occurring at depths between 2 and 6 kilometers (1.2 to 3.7 miles) below sea level. These tremors are considered part of the volcano’s normal background seismicity and indicate a recharging process, rather than an imminent large eruption.
What to Expect in the Future
Given its history of frequent activity and ongoing subsurface processes, Mount St. Helens is highly likely to erupt again. Scientists anticipate that future eruptions will resemble those of its recent past, including various types, frequencies, and magnitudes of activity. However, a large debris avalanche or a major lateral blast, similar to the devastating 1980 event, is not considered likely now that a deep crater has formed.
The exact timing or scale of its next eruption remains impossible to predict precisely years in advance. Nevertheless, the extensive monitoring systems provide early warnings by detecting changes in seismic activity, ground deformation, and gas emissions. Continued observation is paramount for understanding the volcano’s behavior and ensuring public safety, as these systems enable scientists to issue short-term forecasts and warnings if conditions change.