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.
Sub-communities within this community
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Alaska Earthquake Center
Advancing Alaska's resilience to earthquakes through monitoring, research and public engagement
Recent Submissions
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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.
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Moment tensors for the mainshock and aftershocks of the 2018-11-30 Mw 7.1 Anchorage earthquakeWe determine moment tensor solutions for 18 aftershocks of the 2018-11-30 Mw 7.1 Anchorage earthquake, as well as for the mainshock.
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Supplemental analysis for: "Seismic response of Cook Inlet sedimentary basin, southern Alaska"This collection is a supplement to a manuscript in preparation by Kyle Smith and Carl Tape entitled ``Seismic response of Cook Inlet sedimentary basin, southern Alaska,'' to be submitted to Seismological Research Letters.
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Pedestrian Travel-Time Maps for Unalaska/Dutch Harbor, Alaska: An anisotropic model to support tsunami evacuation planningTsunami-induced pedestrian evacuation for the community of Unalaska/Dutch Harbor is evaluated using an anisotropic modeling approach developed by the U.S. Geological Survey. The method is based on pathdistance algorithms and accounts for variations in land cover and directionality in the slope of terrain. We model evacuation of pedestrians to the tsunami hazard zone boundary and to predetermined assembly areas. Pedestrian travel-time maps are computed for two cases: for travel across all viable terrain or by 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. This report was funded by the National Tsunami Hazard Mitigation Program grant to the Alaska Division of Homeland Security and Emergency Management and University of Alaska Fairbanks from the Department of Commerce/National Oceanic at Atmospheric Administration (NOAA). This does not constitute an endorsement by Alaska Earthquake Center (AEC) or NOAA.
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Pedestrian Travel-Time Maps for King Cove, Alaska: An anisotropic model to support tsunami evacuation planningTsunami-induced pedestrian evacuation for the community of King Cove is evaluated using an anisotropic modeling approach developed by the U.S. Geological Survey. The applied 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 the tsunami hazard zone boundary and to predetermined assembly areas. The pedestrian travel-time maps are computed for two cases: for travel across all viable terrain or by 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. This report was funded by the National Tsunami Hazard Mitigation Program grant to the Alaska Division of Homeland Security and Emergency Management and University of Alaska Fairbanks from the Department of Commerce/National Oceanic at Atmospheric Administration (NOAA). This does not constitute an endorsement by Alaska Earthquake Center (AEC) or NOAA.
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Pedestrian Travel-Time Maps for Homer, Alaska: An anisotropic model to support tsunami evacuation planningTsunami-induced pedestrian evacuation for the community of Homer 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 the tsunami hazard zone boundary and to predetermined assembly areas. The pedestrian travel-time maps are computed for two cases: for travel across all variable terrain or by roads only. Results presented here are intended to provide guidance to local emergency management agencies in tsunami inundation assessment, evacuation planning, and public education to mitigate future tsunami hazards. This report was funded by the National Tsunami Hazard Mitigation Program grant to the Alaska Division of Homeland Security and Emergency Management and University of Alaska Fairbanks from the Department of Commerce/National Oceanic at Atmospheric Administration (NOAA). This does not constitute an endorsement by Alaska Earthquake Center (AEC) or NOAA.
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Pedestrian Travel-Time Maps for Chignik, Alaska: An anisotropic model to support tsunami evacuation planningTsunami-induced pedestrian evacuation for the community of Chignik 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 the tsunami hazard zone boundary and to predetermined assembly areas. Pedestrian travel-time maps are computed for two cases: for travel across all viable terrain or by 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. This report was funded by the National Tsunami Hazard Mitigation Program grant to the Alaska Division of Homeland Security and Emergency Management and University of Alaska Fairbanks from the Department of Commerce/National Oceanic at Atmospheric Administration (NOAA). This does not constitute an endorsement by Alaska Earthquake Center (AEC) or NOAA.
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Earthquake Stories from Minto and Nenana, AlaskaOn Wednesday October 15, 1947 at 4:10pm local time, a magnitude 7.2 earthquake struck Interior Alaska, near Healy. This is a collection of stories of six life-long Alaskan elders who felt this earthquake and shared their recollections in fall of 2014, sixty-seven years after the earthquake. Geraldine Charlie had recently turned 18 years old and worked in the village store in Minto when the earthquake hit. Geraldine was crouching down to weigh a bag of potatoes at the moment the earthquake hit. She felt dizzy and noticed Coleman lanterns swaying from side to side, and items shook off the shelves. Sarah Silas and Berkman Silas were also in Minto and had been married for three years. Sarah recalls watching her toddler son, who laughed as he tried to maintain his balance as the floor rolled back and forth under his feet. Berkman and other men were ice fishing near Little Goldstream Creek when the earthquake hit. Rafting ice caused the men to run for the shore. Paul Esau was near Tolovana working on the roof of their home. Caroline Ketzler was up in their food cache at their home up the Kantishna River. Henry Ketzler was in a cabin in Nenana and ran for the exit, only to hit the door frame as it shook with the entire house. These are their stories from 1947. Also discussed in these stories are the effects from the 1912 Katmai eruption, the 1937 Salcha earthquake, and the 1964 earthquake.
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Pilot Andy Bachner’s account of the 1964 Alaska earthquakeOn Friday, March 27, 1964, at about 4:30pm, a 22-year-old pilot named Andy Bachner took off from Fairbanks International Airport on a training flight for Wien Airlines. Alongside Bachner in the single-engine Tri-Pacer plane was the flight instructor, Don Edgar Jonz. Their instrument training flight took them into the clouds and north of Fairbanks 100 miles, in the vicinity of Beaver Creek. Approximately one hour into the flight, Bachner and Jonz abruptly lost all communication with the ground. Fearing a nuclear strike on Eielson and expecting to see Soviet fighter jets, Bachner continued to fly for approximately 30 minutes until fuel was a consideration, prompting them to return to Fairbanks. Upon landing back at Fairbanks, Bachner and Jonz learned about the catastrophic earthquake in southern Alaska. Jonz was asked by the U.S. Army Corps of Engineers to pilot a flight to southern Alaska to survey the earthquake and tsunami damage. Jonz invited Bachner to pilot the plane, allowing Bachner to gain additional instrument training. The two men boarded a Twin Bonanza plane owned by Frontier Flying Service and were provided with a fancy radio. They flew for approximately six hours that night . They live-radioed what they saw in the twilight, fire light, and light of the full moon, while surveying Anchorage, Whittier, Valdez, and Cordova, and then landing back in Fairbanks early March 28th. On Friday, March 27, 1964, at 5:36pm local time, a magnitude 9.2 earthquake struck south-central Alaska. The earthquake devastated Anchorage with its shaking, and it devastated coastal communities with its tsunami. To date, this was the second largest earthquake ever recorded on Earth (1960 magnitude 9.5 in Chile).
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An improved glimpse into earthquake activity in northeastern AlaskaThe northeastern Brooks Range is long known to be seismically active, but meaningful analysis of the earthquake activity has been limited by the lack of instrumentation. The seismic record in the area dates back to the mid-1970s, and shows a broad northeast-trending zone of earthquake activity. Improvements made in the past 20 years to the permanent seismic network along with new data collected by the temporary USArray network of seismometers located throughout northeastern Alaska have dramatically lowered the earthquake detection threshold in the area. It is now possible to identify patterns within the earthquake data including spatial distribution and occurrence rates, which indicate the presence of previously unrecognized active fault systems. I highlight several such features within the data: a 110 km (60 mi) line of recurring earthquakes near the village of Beaver that strongly suggest a singular fault system; a cluster of earthquakes near the village of Venetie that are likely occurring on a complex active fault system; a years-long mainshock-aftershock sequence of earthquakes near the Draanjik River that began in 2006; and two swarms separated by 50 km (30 mi) in distance and 7 years near the Hulahula River.
