Kīlauea Volcano, one of the most active on Earth, put on a spectacular show in 2018 with an eruption that left scientists and the general public in awe. The eruption was notable not just for its scale but for the fascinating chain of events that led to it. The series of cascading events, starting with relatively small changes within the volcano's plumbing system, culminated in a massive outpouring of lava and the collapse of Kīlauea's summit caldera.
This dramatic episode underscores the complexity and interconnectedness of volcanic processes. Kīlauea's 2018 eruption involved numerous distinct stages, each building upon the previous ones, much like dominoes falling in succession. As the eruption unfolded, scientists at the Hawaiian Volcano Observatory (HVO) were able to track these developments in real-time, providing invaluable insights into the dynamics of volcanic activity.
The journey to the 2018 eruption began years earlier. Evidence suggests that magma started leaking downrift of Pu'u 'Ō'ō as early as 2013, gradually building pressure within the East Rift Zone (ERZ). By late 2017, a restriction had developed in the vent conduit supplying lava to Pu'u 'Ō'ō, causing the lava output to decrease and the system to pressurize. This built-up pressure was a critical factor in the events that followed.
In April 2018, the pressure reached a critical level, driving a small intrusion at Pu'u 'Ō'ō and a larger injection of magma into the Lower East Rift Zone (LERZ). This intrusion led to the LERZ eruption on May 3, 2018, which marked the beginning of the most intense phase of the volcanic activity. The influx of magma into the LERZ also imparted stress on Kīlauea's south flank, triggering a magnitude 6.9 earthquake on May 4. This earthquake, in turn, relieved confining stress on the rift zone, which facilitated even greater magma transport to the eruption site.
The LERZ eruption resulted in a significant amount of magma being drained from Kīlauea's summit magma reservoir, leading to the collapse of the caldera floor. This collapse caused frequent summit earthquakes and small explosions as the pressure within the magma reservoir was maintained, partially sustaining the eruption. The entire sequence of events underscores how a relatively small initial change can lead to significant and unforeseen consequences in a volcanic system.
The 2018 eruption of Kīlauea was challenging to forecast. Although the HVO scientists recognized signs of system-wide inflation and pressurization in the months leading up to the eruption, the precise timing and scale of the activity remained uncertain. The gradual nature of the long-term trends did not clearly point to an imminent hazard, making it difficult to predict the exact location and magnitude of the eruption.
Scientists have since proposed a conceptual model to explain the processes that led to the eruption. According to this model, the prolonged inflation of the summit magma reservoir and slow leakage of magma into the LERZ primed the system for a major event. The short-term perturbations in early 2018, including the developing restriction in the vent conduit and the subsequent pressure buildup, set off a cascading series of events that ultimately culminated in the historic eruption.
This eruption has significant implications for our understanding of volcanic processes and hazard forecasting. It highlights the importance of continuous monitoring and the need for sophisticated models to interpret the complex signals from volcanic systems. Quantitative hazard forecasting tools, such as probabilistic event trees and Bayesian belief networks, allow scientists to integrate various types of data to assess the probability of future volcanic activity.
Despite the advancements in monitoring and modeling, the 2018 Kīlauea eruption also serves as a reminder of the inherent uncertainties in volcanic forecasting. Volcanic systems are complex and often behave in unexpected ways, as evidenced by the unforeseen series of cascading events in 2018. This unpredictability underscores the need for continued research and the development of more comprehensive monitoring and forecasting techniques.
Looking ahead, scientists emphasize the importance of preparing for the possibility of future eruptions by understanding the conditions that prime volcanic systems for such events. The integration of monitoring data with geological and historical records can provide valuable insights into the types and recurrence rates of future volcanic activities.
One key lesson from the 2018 eruption is the importance of maintaining vigilance for the potential of low-probability, high-impact events. Even small changes in a volcanic system can, under the right circumstances, escalate into major eruptions. This awareness is crucial for volcano observatory scientists as they develop long-term forecasts and respond to volcanic crises.
The 2018 Kīlauea eruption was not just a scientific event but also a societal one. It had profound impacts on the local communities in Hawai'i, displacing residents, damaging properties, and altering the landscape. The eruption serves as a stark reminder of the need for effective communication and collaboration between scientists, government agencies, and the public to mitigate the risks associated with volcanic activity.
As the global population continues to grow and more people live in volcanic regions, the need for accurate and timely volcanic hazard assessments becomes increasingly critical. The 2018 Kīlauea eruption provides a valuable case study for improving our ability to forecast and respond to volcanic events, ultimately helping to protect lives and property.
"An important focus of future work should thus be to better understand when systems may be primed such that a small trigger can result in a large eruption" .
