Now showing items 1-20 of 24

    • EarthScope publications database

      Sims, Nealey; Tasa, Keir; Larsen, Jessica; Tape, Carl (2020-08-04)
      We compile a database of EarthScope science publications though May 11, 2020. The database is preserved as a Google Scholar profile available at https://scholar.google.com/citations?user=ZKI-0gUAAAAJ&hl=en&authuser=3
    • Supplemental analysis for: "Seismic response of Nenana sedimentary basin, central Alaska"

      Smith, Kyle (2020-04-17)
      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.
    • Shear-wave splitting observations from local and teleseismic earthquakes recorded in Alaska

      Richards, Cole (2020-04-17)
      This 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.
    • Seismic moment tensor catalog for local and regional earthquakes recorded in Nenana basin, central Alaska

      Smith, Kyle (2020-04-12)
      We 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).
    • Step-response signals recorded during earthquakes in Alaska

      Tape, Carl; Silwal, Vipul; Holtkamp, Stephen (2017-10-27)
      We 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.
    • Supplemental data for "Bear encounters with seismic stations in Alaska and northwestern Canada"

      Tape, Carl; Heath, David C.; Baker, Michael G.; Dalton, Scott; Aderhold, Kasey; West, Michael E. (2019-04-04)
      This collection is established as a supplement to a published manuscript, "Bear encounters with seismic stations in Alaska and northwestern Canada".
    • Using nodal seismic sensors to estimate seismic moment tensors

      Richards, Cole (2019-11-26)
      This 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.
    • Moment tensors for the mainshock and aftershocks of the 2018-11-30 Mw 7.1 Anchorage earthquake

      RIchards, Cole (2019-05-15)
      We determine moment tensor solutions for 18 aftershocks of the 2018-11-30 Mw 7.1 Anchorage earthquake, as well as for the mainshock.
    • Supplemental analysis for: "Seismic response of Cook Inlet sedimentary basin, southern Alaska"

      Smith, Kyle (2019-07-31)
      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.
    • Earthquake Stories from Minto and Nenana, Alaska

      Tape, Carl (2015-07-13)
      On 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.
    • Pilot Andy Bachner’s account of the 1964 Alaska earthquake

      Tape, Carl (2018-09-12)
      On 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).
    • Seismic moment tensor results for nine events in the North Korea region

      Alvizuri, Celso (2018-05-25)
      We determine moment tensor solutions for nine events in the North Korea region. This is a supplement for a published manuscript by Alvizuri and Tape (2018).
    • Seismic moment tensor catalog for crustal earthquakes in the Cook Inlet and Susitna region of southern Alaska

      Silwal, Vipul (2018-05-03)
      We determine moment tensor solutions for 53 earthquakes in southern Alaska, which include 9 in Beluga, 22 in Cook Inlet, and 22 in Susitna. The moment tensors were estimated using both the waveforms and the first-motion polarities. The best solution was obtained through a grid-search in the double-couple moment tensor space using the "cut-and-paste" (CAP) approach of Zhu and Helmberger (1996).
    • Hypocenter estimation for 14 earthquakes in south-central Alaska (1929-1975)

      Lomax, Anthony; Silwal, Vipul; Tape, Carl (2018-05-02)
      We provide results from an analysis of 14 historical earthquakes in the region of Cook Inlet and Susitna, south-central Alaska. Using global arrival times of P and S waves, we estimate probabilistic hypocenters using the code NonLinLoc. We provide the complete results, as well as a set of plots to help interpret the likelihood of each earthquake being within the crust, on the subduction interface, or within the subducting Pacific slab.
    • Seismic moment tensors for six events in the Minto Flats fault zone, 2012-2016

      Silwal, Vipul (2018-04-04)
      Using seismic waveform data, we determine seismic moment tensor solutions for six events in the Minto Flats fault zone, 2012-2016.
    • Moment tensor catalog results for nuclear explosions, volcanic events, and earthquakes

      Alvizuri, Celso (2017-12-01)
      Using seismic waveform data, we determine seismic moment tensor solutions for 12 earthquakes and 17 nuclear explosions at the Nevada Test Site, 3 cavity collapse events, 63 events at Uturuncu volcano (Bolivia), and 21 earthquakes in Alaska. We convey uncertainties in the solutions by displaying a probability density function for source type and by calculating a confidence parameter.
    • Curves Vhat_gamma(omega) (Tape and Tape, 2017) for download and details of their calculation

      Tape, Carl (2017-01-30)
      The files in this collection are a supplement to Tape and Tape (2017). Here we provide precomputed curves Vhat_gamma(omega), where Vhat_gamma(omega) is defined as in Section 2.4 of Tape and Tape (2017). The motivation for this work is the characterization of uncertainties for moment tensors for events in Earth's crust, such as earthquakes, volcanic events, and more. The curves Vhat_gamma(omega) were calculated using Matlab's integral2 function and have an accuracy of approximately 2 x 10^-7.
    • Archival search for felt reports for the Alaska earthquake of August 27, 1904

      Tape, Carl (2016-06-03)
      This report documents a search of primary sources from 1904 to identify felt reports of the 1904-08-27 earthquake in central Alaska. The objective is to use the felt reports to get a better idea for where the earthquake occurred.
    • Step-response signals recorded at seismic stations in Alaska

      Holtkamp, Stephen; Tape, Carl (2016-11-14)
      This technical report documents the occurrence of a "step-response signal" on seismic stations in Alaska. The unwanted signal occurs both during earthquakes and independent of earthquakes. The cause of the signal is unknown to us, though it has previously been identified in the published seismology literature.
    • Analysis of regional seismograms and 3D synthetic seismograms for the 2016-01-24 Mw 7.1 Iniskin earthquake in southern Alaska

      Tape, Carl (2016-11-03)
      I perform two analyses to identify cases of seismogram clipping or other problems (e.g., data gaps) for the 2016-01-24 Mw 7.1 Iniskin, Alaska, earthquake. The first analysis is a comparison of synthetic and observed seismograms: three-component, displacement seismograms filtered between periods 4-80 s. The subset of 141 stations is limited to an oblique rectangular region that is 1200 km x 600 km (Figures 1 and 2) and used in a seismic wavefield simulation with a three-dimensional seismic velocity model. I identify 60 out of 141 stations that are suspected of clipping or other problems. Of the 81 good stations, only 8 are within 250 km of the Iniskin epicenter, and all 8 stations are outside of Cook Inlet basin, which strongly amplifies ground motion (both in data and in synthetics). The second, much simpler, analysis is to identify clipping based on the maximum counts on the waveforms. The max-counts approach reveals general agreeement with the classification based on long-period data and synthetics. The analysis suggests that (1) some recorded waveforms that exceed clipping levels may still be usable for some modeling purposes, and (2) some recorded waveforms that appear to be suitable for modeling purposes should probably be discarded due to clipping at high frequencies. The identification of suspected stations, along with the waveform comparisons, may help network operators assess the possibility of unexpected performance during the Mw 7.1 slab earthquake.