• 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.
    • 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.
    • 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.
    • 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).
    • 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).
    • 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).
    • 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 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.
    • 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.