The Pacific Plate motion relative to the North American plate is shown with arrows. Alaska is the most geologically active part of North America. Active plate tectonics creates the high topographic relief and aggressive erosion by gravity, glaciers, rivers, and weathering creates unstable slopes. Southcentral Alaska overlies the subduction zone of the Pacific Plate where earthquakes are frequent and often high magnitude Figure 1. Plate tectonics along with isostatic rebound result in rapidly uplifting mountains.
For example, the Wrangell-St. Elias and Glacier Bay areas are uplifting at a rate of more than 0. Geohazards include earthquakes, landslides, rockfall, debris flows, glacier outburst floods, ice and snow avalanches, river erosion and deposition, and other hazards associated with geological processes. The active tectonics and extreme climatic processes combine to make geohazards common in Alaska.
Much of the mystique of Alaska is its essence of wilderness where the land is expected to be wild and unpredictable. The awe-inspiring landscape, harsh climate, and obvious forces of nature make it an exciting tourist destination. As such, geohazards are expected as a part of life, or even a badge of honor, for those who can overcome their challenges. With the expectation of Alaska being wild, it is often hard to justify diverting valuable resources to study a process that occurs infrequently.
Earthquake along the Alaska Penninsula!
Furthermore, because Alaska's parks have so many types of geohazards, it can appear futile to attempt managing the potential risk. It is often the case in the remote Alaska parks that geohazard events unfold without notice. For example, the massive Taan Inlet landslide and tsunami in Wrangell-St. Elias National Park and Preserve was not noticed until researchers detected it on seismometers and confirmed it by satellite imagery days later see The Taan Fiord Landslide and Tsunami.
No people were present, so no one was at risk. Only a remote airstrip was destroyed by the tsunami. Without exposure to a geohazard, there is no risk. However, events like this are occurring more frequently in Alaska parks, so it is important to recognize the nexus where infrastructure or people are exposed to geohazards.
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- Geohazards in Alaska’s National Parks (U.S. National Park Service).
- High Performance Embedded Architectures and Compilers: Fourth International Conference, HiPEAC 2009, Paphos, Cyprus, January 25-28, 2009. Proceedings!
In this issue of Alaska Park Science , the scientists that study geohazards present where they may occur, what we know about the processes influencing them, and what can be done to improve safety and resiliency. After reading these articles, a reader will better understand the state of the science for geologic and climatic processes that cause geohazards.
Geohazards exist with or without resources, infrastructure, or humans present. The hazard level is a function of the frequency of events and their magnitudes. Risk is a function of the probability of a geohazard, but also exposure levels, vulnerability, and resiliency. Although the exact timing of most geohazards is hard to determine, the areas at risk can be identified mapped and our vulnerabilities to these hazards can be assessed.
Only with this knowledge can we manage our exposure and develop resilient systems to protect people and infrastructure from geohazards. People are generally poor at assessing the risk of low-frequency events, even if they potentially pose catastrophic consequences. It is often the case that while hazards are recognized by geologists, the extent of a geohazard is understood only after catastrophic events.
The NPS also has a responsibility to protect people as well as park resources. While the NPS is charged with unimpaired preservation of naturally occurring geologic processes and scenery, risk reduction is also a central management strategy. This Alaska Park Science issue was created to highlight the state of the knowledge about geohazards as a park management issue and to better inform decision makers and the public.
Geohazards are present in every park in Alaska Table 1. Some parks were formed due to geohazards; for example Aniakchak National Monument was created after the eruption of Aniakchak, and Katmai National Monument was created after the eruption of Novarupta see Volcanic Ash Resuspension from the Katmai Region. For each type of geohazard in Alaska, there are government agencies developed to study, evaluate, and warn the public about geohazards. For some geohazards, there are robust monitoring systems in place that can provide early warning to help save lives.
For example, the Alaska Volcano Observatory conducts studies to understand the eruptive histories and the potential hazards of active volcanoes.
They have a monitoring system of seismometers, infrasound microphones, and satellite data that geophysicists use to detect eruptions and send notifications through a widely available warning system. In contrast, there are other geohazards, like landslide-generated tsunamis that are less understood and are not actively monitored.
Landslide-generated tsunamis have occurred in Alaska parks and some have killed people, but the areas with landslide potential have yet to be mapped, so the risk to visitor safety from landslide-generated tsunamis is largely unknown. Elias National Park and Preserve. Therefore, the known history of landslide events may not be useful for quantifying the frequency and magnitude of future events.
Particularly for large landslides, the historic record in Alaska goes back less than a century. Also, places prone to landslide-generated tsunamis are in steep fjords that have only recently been deglaciated. Internet Explorer. Available for download. Not available in stores. This multidisciplinary monograph provides the first modern integrative summary focused on the most spectacular active tectonic systems in North America. Encompassing seismology, tectonics, geology, and geodesy, it includes papers that summarize the state of knowledge, including background material for those unfamiliar with the region; address global hypotheses using data from Alaska; and test important global hypotheses using data from this region.
Dr. Julie Elliott - Department of Earth, Atmospheric, and Planetary Sciences - Purdue University
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