Impacts of simulated M9 Cascadia Subduction Zone earthquakes considering amplifications due to the Georgia sedimentary basin on reinforced concrete shear wall buildings

2020 ◽  
Vol 50 (1) ◽  
pp. 237-256
Author(s):  
Preetish Kakoty ◽  
Sai Mithra Dyaga ◽  
Carlos Molina Hutt
Keyword(s):  
Reinforced Concrete ◽  
Subduction Zone ◽  
Sedimentary Basin ◽  
Shear Wall ◽  
Cascadia Subduction Zone ◽  
Subduction Zone Earthquakes

Performance of Lightly Confined Reinforced Concrete Columns in Long-Duration Subduction Zone Earthquakes

2005 ◽  
Vol 1928 (1) ◽  
pp. 184-192
Author(s):  
Seth E. Stapleton ◽  
Cole C. McDaniel ◽  
William F. Cofer ◽  
David I. McLean
Keyword(s):  
Reinforced Concrete ◽  
Subduction Zone ◽  
Concrete Columns ◽  
Cascadia Subduction Zone ◽  
Longitudinal Reinforcement ◽  
Reinforced Concrete Columns ◽  
Lap Splice ◽  
Western Washington ◽  
Subduction Zone Earthquake ◽  
Subduction Zone Earthquakes

The main goals of this research were to evaluate typical 1950s and 1960s as-built bridge columns in western Washington State in large subduction zone earthquakes and to investigate the dependency of failure mechanisms on loading history. Eight displacement histories were applied to eight nominally identical, half-scale, circular reinforced concrete columns expected to respond primarily in flexure (flexure-dominated). The main design deficiencies were a short longitudinal reinforcement lap splice at the base of the column (35 db) and inadequate transverse reinforcement. Test results showed that the failure mode of reinforced concrete columns was controlled by the column loading history. Three distinct failure mechanisms were observed for columns with an aspect ratio of approximately 4.2, assuming symmetric, double-curvature behavior. Large initial displacements greater than six times the effective yield displacement (Δ y) were likely to result in shear failures. Columns experiencing many displacements less than 4Δ y were likely to fail because of longitudinal reinforcement buckling. Columns subjected to several displacement excursions less than 4Δ y followed by an excursion greater than 6Δ y were likely to fail by longitudinal reinforcement slipping within the splice region. Despite the deficiencies present in circular reinforced concrete bridge columns built before 1975 in western Washington State, this study showed that flexure-dominated columns with a 35 db lap splice in multiple-column bent, three-or four-span bridges were not likely to experience significant damage in the predicted Cascadia Subduction Zone earthquake. However, other components of the bridge need to be assessed to determine whether the global bridge response is acceptable under the predicted Cascadia Subduction Zone earthquake.

Stratigraphic and microfossil evidence for a 4500-year history of Cascadia subduction zone earthquakes and tsunamis at Yaquina River estuary, Oregon, USA

2014 ◽  
Vol 127 (1-2) ◽  
pp. 211-226 ◽  
Author(s):  
Nicholas A. Graehl ◽  
Harvey M. Kelsey ◽  
Robert C. Witter ◽  
Eileen Hemphill-Haley ◽  
Simon E. Engelhart
Keyword(s):  
Subduction Zone ◽  
River Estuary ◽  
Cascadia Subduction Zone ◽  
History Of ◽  
Subduction Zone Earthquakes

Subduction zone heterogeneity observed across the magnitude spectrum for megathrust earthquakes

2021 ◽  
Author(s):  
Susan Bilek ◽  
Emily Morton
Keyword(s):  
Spatial Heterogeneity ◽  
Subduction Zone ◽  
Stress Drop ◽  
Subduction Zones ◽  
Cascadia Subduction Zone ◽  
Ocean Bottom ◽  
Small Earthquake ◽  
Megathrust Earthquakes ◽  
Seismic Slip ◽  
Subduction Zone Earthquakes

<p>Observations from recent great subduction zone earthquakes highlight the influence of spatial geologic heterogeneity on overall rupture characteristics, such as areas of high co-seismic slip, and resulting tsunami generation.  Defining the relevant spatial heterogeneity is thus important to understanding potential hazards associated with the megathrust. The more frequent, smaller magnitude earthquakes that commonly occur in subduction zones are often used to help delineate the spatial heterogeneity.  Here we provide an overview of several subduction zones, including Costa Rica, Mexico, and Cascadia, highlighting connections between the small earthquake source characteristics and rupture behavior of larger earthquakes.  Estimates of small earthquake locations and stress drop are presented in each location, utilizing data from coastal and/or ocean bottom seismic stations.  These seismicity characteristics are then compared with other geologic and geophysical parameters, such as upper and lower plate characteristics, geodetic locking, and asperity locations from past large earthquakes.  For example, in the Cascadia subduction zone, we find clusters of small earthquakes located in regions of previous seamount subduction, with variations in earthquake stress drop reflecting potentially disrupted upper plate material deformed as a seamount passed.  Other variations in earthquake location and stress drop can be correlated with observed geodetic locking variations. </p>

THE TIMING AND DEFORMATION OF CASCADIA SUBDUCTION ZONE EARTHQUAKES FROM COASTAL MARSH RECORDS OF OREGON

2017 ◽  
Author(s):  
Simon E. Engelhart ◽  
◽  
Niamh Cahill ◽  
Andrea Hawkes ◽  
Benjamin P. Horton ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Coastal Marsh ◽  
Cascadia Subduction Zone ◽  
Subduction Zone Earthquakes

Inelastic Structural Response to Cascadia Subduction Zone Earthquakes

1995 ◽  
Vol 11 (1) ◽  
pp. 63-89 ◽  
Author(s):  
M. Lee Marsh ◽  
Christopher M. Gianotti
Keyword(s):  
Subduction Zone ◽  
Structural Response ◽  
Degree Of Freedom ◽  
Cascadia Subduction Zone ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Energy Demands ◽  
Cyclic Displacement ◽  
Energy Dissipated ◽  
Subduction Zone Earthquakes

The effects of postulated Cascadia subduction zone earthquakes on inelastic structural response are examined. The earthquakes considered ranged in size from those previously recorded to the largest plausible event, a magnitude 9.5 earthquake. Artificial acceleration records were generated and used as input for inelastic response history analyses of single-degree-of-freedom systems with bilinear or degrading stiffness hysteretic relationships. The results indicate that the maximum displacements are not significantly greater than those produced by previously recorded events. The inelastic energy dissipated and the numbers of displacement cycles are somewhat greater for the largest events, although the energy demands and the cyclic displacement demands are similar to those from the recorded events for magnitudes up to 8.5.

scholarly journals Rainfall triggers more deep-seated landslides than Cascadia earthquakes in the Oregon Coast Range, USA

2020 ◽  
Vol 6 (38) ◽  
pp. eaba6790
Author(s):  
S. R. LaHusen ◽  
A. R. Duvall ◽  
A. M. Booth ◽  
A. Grant ◽  
B. A. Mishkin ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Pacific Northwest ◽  
Cascadia Subduction Zone ◽  
Mean Annual Precipitation ◽  
Coast Range ◽  
Ground Acceleration ◽  
Oregon Coast Range ◽  
Oregon Coast ◽  
Subduction Zone Earthquakes ◽  
Large Earthquakes

The coastal Pacific Northwest USA hosts thousands of deep-seated landslides. Historic landslides have primarily been triggered by rainfall, but the region is also prone to large earthquakes on the 1100-km-long Cascadia Subduction Zone megathrust. Little is known about the number of landslides triggered by these earthquakes because the last magnitude 9 rupture occurred in 1700 CE. Here, we map 9938 deep-seated bedrock landslides in the Oregon Coast Range and use surface roughness dating to estimate that past earthquakes triggered fewer than half of the landslides in the past 1000 years. We find landslide frequency increases with mean annual precipitation but not with modeled peak ground acceleration or proximity to the megathrust. Our results agree with findings about other recent subduction zone earthquakes where relatively few deep-seated landslides were mapped and suggest that despite proximity to the megathrust, most deep-seated landslides in the Oregon Coast Range were triggered by rainfall.

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