Download or read book Seismological Constraints on Tectonics of Southern and Central Alaska written by Natalia Anatolievna Ratchkovski and published by . This book was released on 2001 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The major emphasis of this thesis is on investigations of earthquake locations and source mechanisms and what we can learn about Earth structure from them. I used a Joint Hypocenter Determination (JHD) method to improve the earthquake locations obtained after routine data processing. Over 15,000 subduction zone earthquakes in sourthern Alaska and over 3,600 crustal earthquakes in central Alaska with magnitudes of ML> 2 that occurred from 1988 to 2000 were relocated. I found that the relative earthquake locations can be improved with the use of the JHD relocation technique (30-60% reduction in RMS residuals). Thus, many details of the subduction zone geometry and crustal structure can be mapped. To constrain source characteristics, I use a moment tensor inversion method that simultaneously inverts for the source parameters and velocity structure. First, I apply this technique to the sequence of strong earthquakes in the Kodiak Island region, including December 6, 1999 and January 10, 2001 MW 7 events. Next, I expand this approach to moderate-sized (ML> 4) crustal earthquakes in central Alaska and calculate 38 moment tensors. I demonstrate that the moment tensor inversion of regional waveforms provides reliable results even when recordings from a single broadband station are used. A catalog of the moment tensors together with the focal mechanisms obtained using conventional P-wave first motion analysis is used to calculate principal stress directions in central Alaska. I find that the stress state in the crust is inhomogeneous and that the orientation of the maximum compressive stress changes from a SE-NW to SSW-NNE orientation from west to east across interior Alaska. One more topic of this thesis is the application of the array analysis to understanding characteristics of anomalous seismic phases observed in the records of the intermediate-depth Alaskan subduction zone eearthquakes. I identified two secondary phases arriving with 1-3 s and 7-12 s delays after the first P-wave arrival. They are interpreted as S-to-P and P-to-S converted phases at the upper/lower surface of the subducted slab"--Leaf iii.

Download or read book Seismological Investigations of Plate Tectonics in South Central Alaska written by John N. Davies and published by . This book was released on 1975 with total page 386 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Seismological Research in Central Alaska written by N. N. Biswas and published by . This book was released on 1974 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: ;Contents: Travel time relations for the crust and upper mantle P-wave phases for central Alaskan data; Seismicity and plate tectonics in South-central Alaska; Earthquake source mechanics for small magnitude earthquakes in central Alaska; Study of Ms-m sub b relations from central Alaska data.

Download or read book Tectonics of the March 27 1964 Alaska Earthquake written by George Plafker and published by . This book was released on 1970 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Active Tectonics and Seismic Potential of Alaska written by Jeffrey T. Freymueller and published by John Wiley & Sons. This book was released on 2013-06-05 with total page 1025 pages. Available in PDF, EPUB and Kindle. Book excerpt: Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 179. 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. It is organized around four major themes: subduction and great earthquakes at the Aleutian Arc, the transition from strike slip to accretion and subduction of the Yakutat microplate, the Denali fault and related structures and their role in accommodating permanent deformation of the overriding plate, and regional integration and large-scale models and the use of data from Alaska to address important global questions and hypotheses. The book's publication near the beginning of the National Science Foundation's EarthScope project makes it especially timely because Alaska is perhaps the least understood area within the EarthScope footprint, and interest in the region can be expected to rise with time as more EarthScope data become available.

Download or read book Constraints on Tectonic Deformation in the Southern Alaska Subduction Zone from Historical Seismicity written by Emile A. Okal and published by . This book was released on 1993 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Alaska s Good Friday Earthquake March 27 1964 written by Arthur Grantz and published by . This book was released on 1964 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Tectonic Growth of a Collisional Continental Margin written by Kenneth D. Ridgway and published by Geological Society of America. This book was released on 2007 with total page 676 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The convergent margin of southern Alaska is considered one of the type areas for understanding the growth of continental margins through collisional tectonic processes. Collisional processes that formed this margin were responsible for multiple episodes of sedimentary basin development, subduction complex growth, magmatism, and deformation. Two main collisional episodes shaped this Mesozoic-Cenozoic continental margin. The first event was the Mesozoic collision of the allochthonous Wrangellia composite terrane. This event represents the largest addition of juvenile crust to western North America in the past 100 m.y. The second event is the ongoing collision of the Yakutat terrane along the southeastern margin of Alaska. This Cenozoic event has produced the highest coast mountain range on Earth (Saint Elias Mountains), the Wrangell continental arc, and sedimentary basins throughout southern Alaska. Active collisional processes continue to shape the southern margin of Alaska, mainly through crustal shortening and strike-slip deformation, large-magnitude earthquakes, and rapid uplift and exhumation of mountain belts and high sedimentation rates in adjacent sedimentary basins. This volume contains 24 articles that integrate new geophysical and geologic data, including many field-based studies, to better link the sedimentary, structural, geochemical, and magmatic processes that are important for understanding the development of collisional continental margins."--Publisher's website.

Download or read book Seismological Studies in South Central Alaska and Northern Mexico written by Oscar Romero-de la Cruz and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The work in this study is focused on two different areas, south-central Alaska and northern Mexico. In the first study area, I calculated dynamic stress drops for moderate sized earthquakes and performed receiver function analyses. The goal of the stress drop studies was to determine if events occurring within the more strongly coupled portion of the subducting slab have higher stress drops. My results shows that higher stress drops correspond to the locked and strongly coupled region in Prince William Sound, and lower stress drops are associated with the Cook Inlet region, a zone of relaxation of the plate interface. The receiver function analysis focused on data from an isolated broad band station on the Kenai Peninsula that may be located near the edge of the strongly coupled portion of the Yakutat microplate. The station recorded global teleseismic events of M>5.5 for a three different periods achieving a total recording of ~9 months. I used these data to determine the crustal structure from the P to S converted phases. The best match to data shows a thickness of 34 km and a Vp/Vs ratio of 1.45 just under the station, but, three other results from different directions obtained values of 28 km and 2.3 toward south of the station, 30 km and 1.98 southwest of the station, and 32 km and 1.63 eastward of the station. This would suggest the presence of a mantle wedge beneath the study area. In the second study area, northern Mexico, I obtained a crustal velocity model by means of the Joint Hypocenter Determination inversion technique using microseismicity and mining blasts in the region as sources. The final model shows the moho depth at 30 km and the upper-lower crust boundary at 21 km. The inclusion of a transition layer at 12 km allowed better adjustment than preliminary starting model of Harder and Keller. The new locations of the epicenters maintain the alignment to the Pitaycachi fault and the mining blasts clusters converge better to the mining locations.

Download or read book Catalog of Earthquakes in South Central Alaska written by John C. Lahr and published by . This book was released on 1973 with total page 74 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effects of the March 1964 Alaska Earthquake on the Hydrology of South central Alaska written by Roger M. Waller and published by . This book was released on 1966 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: Water-level fluctuations, long-term changes, and temporary effects caused by response of the ground water to seismic waves.

Download or read book The Seismic Wavefield in Nenana Basin and Cook Inlet Basin of Alaska written by Kyle K. Smith and published by . This book was released on 2020 with total page 554 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sedimentary basins amplify ground motion from earthquakes which can have severe consequences for major cities on basins like Tokyo and Los Angeles. Ground motion on sedimentary basins is complex and it depends on the geometry and elastic properties. We study the seismic wavefield from ambient noise and earthquake sources in Nenana Basin and Cook Inlet Basin with seismic stations from the Fault Locations and Alaska Tectonics from Seismicity (FLATS) and Southern Alaska Lithosphere and Mantle Observation Network (SALMON) projects. The FLATS project consists of 13 seismic stations placed over the Nenana Basin region in Central Alaska from 2014 to 2019. In South-Central Alaska, 28 seismic stations were placed around the Cook Inlet Region from 2015-2017 for the SALMON project. In this thesis, we have established two valuable data sets of events that can be used to better understand the complex influence of sedimentary basins on the seismic wavefield. Our analyses help quantify the frequency-dependent amount of amplification that occurs within these sedimentary basins. A greater understanding of ambient noise can improve site selection as well as understanding other forces of nature. Many FLATS stations are near trees and a river, so we quantify the influence of river, wind and basin on ambient noise. We analyze ambient noise in the frequency domain with power spectral densities on annual, daily and hourly time scales. Rivers affect ground motion from shearing and turbulent forces. For FLATS stations within several meters of the Tanana River, we found consistent seasonal perturbations around 10 Hz. A comparison of the 10 Hz signal with river stage height, measured 14 km upriver, shows strong correlations exist during the summer and ambient noise increases by 40 dB. In the town of Nenana, a weather station shows wind occurs less during the winter than summer. Wind can directly interact with the ground through shearing forces or indirectly with the transfer of energy through trees. In this study, we found that wind can affect the ground motion by at least 10 dB for

Download or read book Effects of the Earthquake of March 27 1964 on Air and Water Transport Communications and Utilities Systems in South central Alaska written by Edwin Butt Eckel and published by . This book was released on 1967 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: A description of the disruption and damage that all systems sustained from seismic vibrations and tectonic changes and from the slides, waves, and fires caused by the earthquake.

Download or read book Toward Reduction of Losses from Earthquakes written by National Research Council (U.S.). Committee on the Alaska Earthquake and published by . This book was released on 1979 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Seismic hazard Analysis of the Nenana Agricultural Development Area Central Alaska written by Hans Pulpan and published by . This book was released on 1988 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book U S Geological Survey Professional Paper written by and published by . This book was released on 1984 with total page 628 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Geologic Studies in Alaska by the U S Geological Survey During written by and published by . This book was released on 1997 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt: