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Tectonostratigraphy and major structures of the Georgian Greater Caucasus: Implications for structural architecture, along-strike continuity, and orogen evolution Tectonostratigraphy and major structures of the Georgian Greater Caucasus: Implications for structural architecture, along-strike continuity, and orogen evolution

Although the Greater Caucasus Mountains have played a central role in absorbing late Cenozoic convergence between the Arabian and Eurasian plates, the orogenic architecture and the ways in which it accommodates modern shortening remain debated. Here, we addressed this problem using geologic mapping along two transects across the southern half of the western Greater Caucasus to reveal a...
Authors
Charles Cashman Trexler, Eric Cowgill, Nathan A Niemi, Dylan A Vasey, Tea Godoladze

20th-century strain accumulation on the Lesser Antilles megathrust based on coral microatolls 20th-century strain accumulation on the Lesser Antilles megathrust based on coral microatolls

The seismic potential of the Lesser Antilles megathrust remains poorly known, despite the potential hazard it poses to numerous island populations and its proximity to the Americas. As it has not produced any large earthquakes in the instrumental era, the megathrust is often assumed to be aseismic. However, historical records of great earthquakes in the 19th century and earlier, which...
Authors
Belle E. Philibosian, Nathalie Feuillet, Jennifer Weil-Accardo, Eric Jacques, Abel Guihou, Anne-Sophie Meriaux, Andre Anglade, Jean-Marie Saurel, Sebastien Deroussi

Open-source resources help navigate new IM regulations Open-source resources help navigate new IM regulations

The revision of federal safety regulations for integrity management of gas transmission pipelines to require explicit consideration of seismicity increases the importance for operators to be actively identifying high-consequence areas (HCAs), evaluating seismic-related threats, and choosing a risk model to support risk management decisions. To ensure equal access to information by both...
Authors
N. Simon Kwong, Kishor S. Jaiswal, J. W. Baker, Nico Luco, K. A. Ludwig, Vasey J. Stephens

Estimates of metals contained in abyssal manganese nodules and ferromanganese crusts in the global ocean based on regional variations and genetic types of nodules Estimates of metals contained in abyssal manganese nodules and ferromanganese crusts in the global ocean based on regional variations and genetic types of nodules

Deep-ocean ferromanganese crusts and manganese nodules are important marine repositories for global metals. Interest in these minerals as potential resources has led to detailed sampling in many regions of the global ocean, allowing for updated estimates of their global extent. Here, we present global estimates of total tonnage as well as contained metal concentrations and tonnages for
Authors
Kira Mizell, James R. Hein, Manda Viola Au, Amy Gartman

Seismic site characterization with shear wave (SH) reflection and refraction methods Seismic site characterization with shear wave (SH) reflection and refraction methods

Reflection and critically refracted seismic methods use traveltime measurements of body waves propagating between a source and a series of receivers on the ground surface to calculate subsurface velocities. Body wave energy is refracted or reflected at boundaries where there is a change in seismic impedance, defined as the product of material density and seismic velocity. This article...
Authors
James A. Hunter, Heather L. Crow, William J. Stephenson, Andre J.-M. Pugin, Robert Williams, James B. Harris, Jackson K. Odum, Edward W Woolery

An assessment of uncertainties in VS profiles obtained from microtremor observations in the phased 2018 COSMOS blind trials An assessment of uncertainties in VS profiles obtained from microtremor observations in the phased 2018 COSMOS blind trials

Site response is a critical consideration when assessing earthquake hazards. Site characterization is key to understanding site effects as influenced by seismic site conditions of the local geology. Thus, a number of geophysical site characterization methods were developed to meet the demand for accurate and cost-effective results. As a consequence, a number of studies have been...
Authors
Michael W. Asten, Alan Yong, Sebastiano Foti, Koichi Hayashi, Antony J. Martin, William J. Stephenson, John F. Cassidy, Jacie Coleman, Robert L. Nigbor, Silvia Castellaro, Kosuke Chimoto, Ikuo Cho, Cecile Cornou, Takumi Hayashida, Manuel Hobiger, Chun-Hsiang Kuo, Albert Macau, E. Diego Mercerat, Sheri Molnar, Passakorn Pananont, Marco Pilz, Nakhorn Poovarodom, Esteban Saez, Marc Wathelet, Hiroaki Yamanaka, Toshiaki Yokoi, Don Zhao

Zoning Verification in Mexico City Using Strong Motions of the M7.1 Puebla-Morelos Earthquake of September 19, 2017 Zoning Verification in Mexico City Using Strong Motions of the M7.1 Puebla-Morelos Earthquake of September 19, 2017

Mexico City suffers extensive damage from large earthquakes that originate at far distances due mainly to densely built areas on a filled lakebed. Seismic design codes in Mexico recognize the site-specific issues in Mexico City by acknowledging zones that represent lakebed as being riskier compared to other Mexico City areas. At the time of the 19 September 1985 M8.1 Michoacán Earthquake...
Authors
Mehmet Celebi, Valerie J. Sahakian, Diego Melgar, Luis Quintanar

Responses of the Carquinez, California suspension bridge during the MW6.0 South Napa earthquake of August 24, 2014 Responses of the Carquinez, California suspension bridge during the MW6.0 South Napa earthquake of August 24, 2014

The behavior of the suspension bridge in Carquinez, CA, during the Mw6.0 24 August 2014 South Napa, CA earthquake is studied using data recorded by an extensive array of accelerometers. Modes, corresponding frequencies and damping are identified and compared with previous studies that used ambient data of the deck only plus mathematical models. Data are systematically analyzed for...
Authors
Mehmet Celebi, S. F. Ghahari, E. Taciroglu

Landslides triggered by the 2002 M 7.9 Denali Fault earthquake, Alaska, USA Landslides triggered by the 2002 M 7.9 Denali Fault earthquake, Alaska, USA

The 2002 M 7.9 Denali earthquake in Alaska, USA, was the largest inland earthquake in North America in nearly 150 years. The earthquake involved oblique thrusting but mostly strike-slip motion, and faults ruptured the ground surface over 330 km. Fault rupture occurred in a rugged, mountainous, subarctic environment with extensive permafrost and variable glaciation, geology, and...
Authors
William H. Schulz

Preliminary study of correlation of natural periods and damping percentages of tall buildings in several countries Preliminary study of correlation of natural periods and damping percentages of tall buildings in several countries

Fundamental periods (T) and critical damping percentages (ζ) of 41 tall buildings in several countries form the basis of this preliminary study. Correlation between building height and fundamental period for steel and reinforced concrete buildings clearly shows a linear variation but with a large standard deviation, most likely due to considerable variation in the designs of structural...
Authors
Mehmet Celebi

Diagenesis of Vera Rubin ridge, Gale crater, Mars from Mastcam multispectral images Diagenesis of Vera Rubin ridge, Gale crater, Mars from Mastcam multispectral images

Images from the Mars Science Laboratory (MSL) mission of lacustrine sedimentary rocks of Vera Rubin ridge on “Mt. Sharp” in Gale crater, Mars, have shown stark color variations from red to purple to gray. These color differences crosscut stratigraphy and are likely due to diagenetic alteration of the sediments after deposition. However, the chemistry and timing of these fluid...
Authors
Briony H. N. Horgan, Jeffrey R. Johnson, Abigail A. Fraeman, Melissa Rice, Christina Seeger, James F. Bell, Kristen A. Bennett, Edward A. Cloutis, Lauren A. Edgar, Jens Frydenvang, John P. Grotzinger, Jonas L’Haridon, Samantha Jacob, Nicolas Mangold, Elizabeth B. Rampe, Frances Rivera-Hernandez, Vivian Z. Sun, Lucy Thompson, Danika F. Wellington

Multi-period response spectra Multi-period response spectra

Multi-period response spectra (MPRS) are incorporated in the development of seismic design ground motions in the 2020 edition of the NEHRP Recommended Seismic Provisions for New Buildings and Other Structures (2020 NEHRP Provisions) and are approved for adoption in the American Society of Civil Engineers (ASCE) Standard, Minimum Design Loads and Associated Criteria for Buildings and...
Authors
Sanaz Rezaeian, Nico Luco, C. A. Kircher
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