Summary
Highlights
In October 2004, Mount St. Helens showed ominous signs of reawakening with steam and ash plumes, prompting fears of another massive explosion. This led scientists to reflect on the events of May 18, 1980, when a 5.1 magnitude earthquake triggered the largest landslide in recorded history, causing the volcano's northern flank to collapse and releasing millions of tons of magma. The eruption created a pyroclastic flow, flattening forests, choking Spirit Lake, and extinguishing virtually all life over 200 square miles, killing 57 people and drastically altering the mountain's shape.
Weeks after the 1980 eruption, scientists, including Dan Dzurisin, arrived at the still-rumbling crater, describing a new, unfamiliar world of steam and cascading rocks. Mount St. Helens is located on the Pacific Ring of Fire, a vast seismic zone where tectonic plates converge. The subduction of the Pacific plate beneath the North American plate creates pressure and friction, melting rock into magma that fuels volcanic eruptions. Understanding these processes is crucial for predicting future events and preventing further destruction.
Biologist Charlie Crisafulli, one of the leading experts on the mountain's ecology, began surveying the devastation. To his surprise, life started to return almost immediately. He discovered Northern pocket gophers, which survived the blast underground, and later, resilient prairie lupins flourishing on the barren pumice plane. These 'pioneering species' played a crucial role in enriching the nutrient-poor volcanic soil, with lupins providing nitrogen and gophers mixing organic matter through their burrowing, paving the way for other life forms.
By fall of 1980 and into 1981, geologists observed a lava dome rising in the crater, growing several hundred feet taller and doubling in diameter. Scientists installed seismometers to monitor the internal activity. They discovered a cyclical pattern of seismic activity, indicating lava movement, followed by periods of quiet and then renewed growth. This dome-building continued for five years, with the dome reaching nearly 1,000 feet at its peak. This predictable pattern abruptly ended in late 1986, leaving scientists to wonder if the mountain had gone back to sleep.
While the volcano slept, Spirit Lake, once a lifeless, bacteria-filled black water, began a remarkable recovery. Microscopic phytoplankton, brought in by birds or wind, started to colonize the lake three years post-eruption, generating oxygen and forming the base of a new aquatic food web. Within a decade, the lake teeming with amphibians and fish, brought by fishermen, indicating a return to normal water quality and demonstrating nature's surprising speed of recovery.
In September 2004, seismic tremors signaled Mount St. Helens' reawakening, leading to explosive steam and ash eruptions. After these initial bursts, a new, strange phenomenon emerged: giant, solid blocks of lava, some as tall as skyscrapers, pushing out of the crater floor. These 'spines' generated a unique, repetitive seismic signature, dubbed 'drum beats,' unlike anything seen before. Geologists, like John Pallister, rushed to analyze these new lava samples, seeking to understand this novel eruption style and its implications for future activity.
John Pallister's analysis of lava samples from different eruptions revealed a crucial insight: the amount of gas determines the eruption's nature. The 1980 eruption's lava was highly gassy, leading to an explosive event. The 1983 dome-building lava had less gas, while the 2005 spine-forming lava was nearly degassed, pushing up solid rock. This 'gas budget' concept explained the varied eruption styles, suggesting that the lava under Mount St. Helens was running low on gas, leading to less explosive events. The 'drum beats' seismic activity ceased completely in 2007, indicating the lava had finally run out of gas.
Geologists examine the exposed rock layers in the crater walls to reconstruct Mount St. Helens' eruptive history. They found evidence of major eruptions in the past, some much larger than 1980, occurring with varied frequencies, including two large eruptions within three years around 500 years ago. This historical record complicates predictions, indicating that while a large eruption might typically take a thousand years to build up, the volcano is capable of unexpected and rapid, powerful events. Scientists agree another eruption is inevitable, but its timing and magnitude remain unknown, posing a significant challenge for forecasting and public safety.
Over 30 years, Mount St. Helens has provided an extraordinary journey of discovery, revealing nature's remarkable ability to recover from devastation faster than anticipated. The ecological return, with new species and complex food webs, is a testament to natural resilience. However, the mountain continues to be a 'ticking time bomb,' with scientists still wrestling with fundamental questions about when and how big its next eruption will be. Despite continuous research, a 'silver bullet' for accurate prediction remains elusive, leaving the future of Mount St. Helens a compelling mystery.