RSS 1.0Geophysical Institute
At the Geophysical Institute the diversity of our research focus is reflected by our disciplinary-based, functional groupings of faculty and research staff. These divisions are: space physics and aeronomy, atmospheric sciences, snow, ice, and permafrost, seismology, volcanology, and tectonics and sedimentation. Along with an ubiquitous, cross-discipline remote sensing group, these research divisions reflect the range and diversity of the active scientific research projects which reach from the center of the sun to the center of the earth and beyond.
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Alaska Earthquake Center
Advancing Alaska's resilience to earthquakes through monitoring, research and public engagement
Collections in this community
Recent Submissions
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PEDESTRIAN TRAVEL-TIME MAPS FOR WHITTIER, ALASKA: An anisotropic model to support tsunami evacuation planningTsunami-induced pedestrian evacuation for the community of Whittier is evaluated using an anisotropic modeling approach developed by the U.S. Geological Survey. The method is based on path-distance algorithms and accounts for variations in land cover and directionality in the slope of terrain. We model evacuation of pedestrians to exit points from the tsunami hazard zone boundary. The pedestrian travel is restricted to the roads only. Results presented here are intended to provide guidance to local emergency management agencies for tsunami inundation assessment, evacuation planning, and public education to mitigate future tsunami hazards.
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PEDESTRIAN TRAVEL-TIME MAPS FOR SITKA, ALASKA: An anisotropic model to support tsunami evacuation planningTsunami-induced pedestrian evacuation for Sitka is evaluated using an anisotropic modeling approach developed by the U.S. Geological Survey. The method is based on path-distance algorithms and accounts for variations in land cover and directionality in the slope of terrain. We model evacuation of pedestrians to exit points from the tsunami hazard zone. The pedestrian travel is restricted to the roads only. Results presented here are intended to provide guidance to local emergency management agencies for tsunami inundation assessment, evacuation planning, and public education to mitigate future tsunami hazards.
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PEDESTRIAN TRAVEL-TIME MAPS FOR PERRYVILLE, ALASKA: An anisotropic model to support tsunami evacuation planningTsunami-induced pedestrian evacuation for the community of Perryville is evaluated using an anisotropic modeling approach developed by the U.S. Geological Survey. The method is based on path-distance algorithms and accounts for variations in land cover and directionality in the slope of terrain. We model evacuation of pedestrians to exit points located at the tsunami hazard zone boundary. Pedestrian travel-time maps are computed for two cases: i) travel to an existing evacuating shelter and ii) travel to either the evacuation or an alternative shelter. Results presented here are intended to provide guidance to local emergency management agencies for tsunami inundation assessment, evacuation planning, and public education to mitigate future tsunami hazards.
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PEDESTRIAN TRAVEL-TIME MAPS FOR CORDOVA, ALASKA: An anisotropic model to support tsunami evacuation planningTsunami-induced pedestrian evacuation for Cordova is evaluated using an anisotropic modeling approach developed by the U.S. Geological Survey. The method is based on path-distance algorithms and accounts for variations in land cover and directionality in the slope of terrain. We model evacuation of pedestrians to exit points from the tsunami hazard zone. The pedestrian travel is restricted to the roads only. Results presented here are intended to provide guidance to local emergency management agencies for tsunami inundation assessment, evacuation planning, and public education to mitigate future tsunami hazards.
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Seismicity and Stresses in the Kantishna Seismic Cluster, Central AlaskaThe Kantishna Cluster is an enigmatic and energetic cluster of earthquakes located in central Alaska, just to the northwest of Mt. McKinley/Denali and adjacent to the Denali Fault. The Kantishna Cluster has no visible fault traces, and is often speculated to have a connection to the Denali Fault. The Kantishna Cluster is located at a hub of tectonic activity including Bering Block rotation to the west, bookshelf faulting to the northeast, and rotation of southern Alaska due to Pacific plate convergence to the south. The intention of this study was to broaden the knowledge base about the Kantishna Cluster and use the Mw 7.9 Denali Fault earthquake to find a relationship between the cluster and the Denali Fault Zone. Rate calculations in conjunction with z- and b-value changes show that the Denali Fault earthquake had little influence on the seismicity of the Kantishna Cluster, with the exception being the southern most portion closest to the Denali Fault. The highly variable background rate of seismicity in the Kantishna Cluster makes seeing changes in the seismicity difficult. Stress tensor inversions suggest a change in the stresses in the Kantishna Cluster; however, triangle diagram comparisons show that the pattern of earthquake mechanism types did not change. Coulomb stress change calculations predict small changes that were not observed in the data. Double difference hypocentral relocations show that the cloud of earthquakes collapses down to several distinct features. Seismicity trends resolved from hypocentral relocations made it possible to infer fault planes or planar structures in the region. The newly uncovered structures are utilized in the formation of a model involving two wedges to describe the seismicity in the Kantishna Cluster. The two wedges are being “squeezed” in opposite directions accommodating for compression across the cluster due to Pacific plate convergence.
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Recent and Possible Future Changes in PermafrostRecent observations indicate a warming of permafrost in many northern regions with the resulting degradation of ice-rich and carbon rich permafrost. Permafrost temperature has increased by 0.5°C to 3°C in the northern Hemisphere during the last 30-40 years (Romanovsky et al., 2010).
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Supplemental analysis for: "Seismic response of Nenana sedimentary basin, central Alaska"This collection is a supplement to a manuscript in preparation by Kyle Smith, Carl Tape, and Victor Tsai entitled "Seismic response of Nenana sedimentary basin, central Alaska," to be submitted to Bulletin of the Seismological Society of America.
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Shear-wave splitting observations from local and teleseismic earthquakes recorded in AlaskaThis collection contains shear wave splitting measurements for earthquakes recorded in south-central Alaska. These data support the 2020 Master's thesis of Cole Richards, which is being adapted and prepared for submission as a manuscript.
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Seismic moment tensor catalog for local and regional earthquakes recorded in Nenana basin, central AlaskaWe determine moment tensor solutions for 33 earthquakes recorded in the Nenanabasin region of central Alaska. For each earthquake, the best solution is obtained using a grid-search over depth, magnitude, and double-couple moment tensors by using the "cut-and-paste" (CAP) approach of Zhu and Helmberger (1996).
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Step-response signals recorded during earthquakes in AlaskaWe present waveform record sections of 18 earthquakes recorded the Minto Flats fault zone in central Alaska. These include the largest earthquakes to have occurred within the Minto Flats fault zone since the installation of the 13-station FLATS network in September 2015 (Tape and West, 2014). Several seismograms from these earthquakes exhibit a ``step-response signal'' that is a long-period, unwanted signal that does not reflect regional ground motion. We use the term ``anomalously high amplitudes'' to refer to amplitudes within a certain bandpass that exceed the amplitude of earthquake ground motion (within the same bandpass). We attribute anomalously high amplitudes to three possibilities: (1) step-response signal due to local tilt or other effect, (2) step-response signal due to defective sensor, (3) digitizer clipping, (4) high noise (especially before the earthquake). We find widespread occurrences of the step-response signal for earthquakes in the Minto Flats fault zone.
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Supplemental data for "Bear encounters with seismic stations in Alaska and northwestern Canada"This collection is established as a supplement to a published manuscript, "Bear encounters with seismic stations in Alaska and northwestern Canada".
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Using nodal seismic sensors to estimate seismic moment tensorsThis report has two documents pertaining to seismic data recorded by a 400-sensor array in central Alaska between February and March, 2019. The first part examines the influence of removing the instrument response on the amplitude of filtered waveforms. The second part shows how the array of sensors can be used to estimate source mechanisms for local earthquakes.
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Manuscript - Ionospheric heating experiment with HF frequency-sweeping -- original radar power dataThis is the original data from the UHF diagnostic radar at HAARP during the experiment. The data represent the total back-scattered power (as function of time) from the Langmuir Parametric Decay Instability that occurs at a height immediately below the HF cut-off height that corresponds to the frequency of the high-power HF wave from the HAARP facility.
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Manuscript - Ionospheric heating experiment with HF frequency-sweeping -- supplemental TEC dataThis TEC data includes the altitude of the TEC measurements inside the HAARP beam. The TEC data were acquired using an oblique ray path through the HAARP beam.
