In a devastating event that has underscored the environmental fragility of Alaska, a powerful atmospheric river brought heavy rainfall to the southern region of the state in early August 2024. This event culminated in a large-scale landslide and tsunami that affected Pedersen Lagoon, resulting in significant destruction to the local ecosystem and infrastructure.
The Atmospheric River’s Impact
The atmospheric river, a long, narrow band of concentrated moisture in the atmosphere, brought intense rainfall to Alaska, leading to a series of events that culminated in the landslide and tsunami. The event occurred on August 7th when a series of events started at a slope in the upper northwest of the Pedersen Lagoon, located in the vicinity of Seward, Alaska, about 20 miles southwest of the city.
Landslide and Tsunami Formation
The landslide involved approximately 2 million cubic meters of rock and debris, which moved down the slope and into the water, triggered by the intense rainfall. The United States Geological Survey (USGS) estimated that the landslide involved around 2 million cubic meters of material.
Upon entering the lagoon, the descending mass of rock and debris caused a tsunami of approximately 56 feet (17 meters) in height. The resulting waves collided with the eastern slope of the lagoon and also flowed across the land separating the upper and lower parts of the lagoon, dissipating on the eastern shore of the lower lagoon.
Satellite Imagery and Damage Assessment
Satellite imagery captured by the Landsat 9 satellite equipped with the Operational Land Imager (OLI-2) on August 20th provided a visual account of the aftermath. The images revealed the extensive destruction of vegetation and infrastructure, including the eradication of trees and vegetation in the area. Additionally, it showed the impact on the local community, with reports of damage to a boardwalk at a hotel located on the eastern shore of the lagoon downstream.
Environmental Implications
This event highlights the vulnerability of the region to environmental changes, particularly the retreat of glaciers. The retreat of glaciers like Pedersen, which has been observed over the past four decades, has increased the instability of slopes in areas sculpted by glaciers, such as the cliffs on either side of the fjords in southern Alaska.
Scientific Insights and Research
Research conducted over the period from 1984 to 2021, using Landsat imagery, has shown that Pedersen Glacier, one of three terminal glaciers in Kenai Fjords National Park, has retreated by 2 miles (3.2 kilometers) during this time. This retreat has led to increased instability in the slopes, making them more susceptible to landslides, such as the one that occurred in August 2024.
Conclusion
The event at Pedersen Lagoon serves as a stark reminder of the interconnectedness between climate change, environmental changes, and natural disasters. It underscores the need for increased monitoring and preparedness in regions vulnerable to such events, particularly in areas where glaciers are retreating, increasing the risk of landslides and tsunamis.
Source and Further Reading
For more information, visit ScitechDaily for a detailed account of this event and its environmental implications.
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