The Darrington seismic zone in northwestern Washington

1989 ◽  
Vol 79 (6) ◽  
pp. 1833-1845
Author(s):  
J. E. Zollweg ◽  
Peggy A. Johnson
Keyword(s):  
Surface Expression ◽  
Seismic Zone ◽  
Single Event ◽  
North Cascades ◽  
Nodal Plane ◽  
Thrust Faulting ◽  
The North ◽  
Crustal Earthquakes ◽  
The Pacific ◽  
Composite Focal Mechanism

Abstract Earthquakes occurring between 1971 and 1988 are evidence for a small zone of crustal seismicity under the western North Cascades near Darrington, Washington. Better-quality hypocenters imply the activity occurs on a fault or fault zone striking N80°W ± 20°, dipping nearly south at 40° ± 15°, with a length along strike of at least 10 km and possibly 20 km or more. We term this feature the Darrington Seismic Zone (DSZ). Focal depths range between 3 and 15 km. A single-event and a composite focal mechanism show nearly pure thrust faulting with one nodal plane in agreement with the hypocenter pattern. P axes strike N20°W to N25°W, in accord with a regional stress direction due to relative motion of the Pacific and North American Plates. No mapped fault can be identified as the surface expression of the zone. The area of the DSZ is adequate to generate a magnitude 5+ earthquake should it rupture in a single event, and an ML 5.6±earthquake on 29 April 1945 in the Cascades ESE of Seattle demonstrates that crustal earthquakes having such magnitudes are possible beneath the western North Cascades. The DSZ is the first crustal seismogenic structure to be identified beneath the North Cascades.

The moss flora of the alpine – high subalpine Chowder Ridge area, western North Cascades Range, Washington State, U.S.A.

1986 ◽  
Vol 64 (1) ◽  
pp. 146-150 ◽  
Author(s):  
John R. Spence
Keyword(s):  
Rocky Mountain ◽  
High Elevation ◽  
Washington State ◽  
Western North America ◽  
North Cascades ◽  
The West ◽  
The North ◽  
The Pacific ◽  
Ridge Area ◽  
First Time

Chowder Ridge, a high elevation area near Mt. Baker, Washington State, possesses a moss flora of 77 species based on collections made during two visits. Three species, Dicranum muehlenbeckii B.S.G., Rhacomitrium microcarpon (Hedw.) Brid., and Mnium arizonicum Amann, are reported new to Washington State. Coscinodon calyptratus (Hook.) C Jens. and Grimmia ovalis (Hedw.) Lindb. are noted for the first time from the west slope of the North Cascades. Chowder Ridge harbors an unusually large number of disjunts of the Rocky Mountain interior compared with typical sites on the west slope of the North Cascades, while the Pacific North American element is underrepresented. The bulk of the flora consists of species widespread in western North America.

Attenuation patterns in the Pacific Northwest based on intensity data and the location of the 1872 North Cascades earthquake

1979 ◽  
Vol 69 (2) ◽  
pp. 531-546
Author(s):  
Stephen D. Malone ◽  
Sheng-Sheang Bor
Keyword(s):  
Pacific Northwest ◽  
Attenuation Factor ◽  
Puget Sound ◽  
Empirical Relation ◽  
Intensity Data ◽  
North Cascades ◽  
The North ◽  
The Pacific ◽  
The Difference ◽  
Eastern Washington

abstract Intensity data from 14 historic earthquakes in or near Washington State, as reported at over 300 localities, are used to study the attenuation structure in Washington. The empirical relation of Evernden (1975) is used to determine the size and depth for each earthquake and the local attenuation factor, k, for two physiographic parts of the state. The value for k in the Puget Sound region and north into Canada is 134, while k=112 is more appropriate for eastern Washington and northern Oregon. Individual local amplification factors are computed for all localities at which four or more earthquakes have been felt by averaging the difference between the computed intensity and reported intensity at each site. Using these correction factors, the intensities for the North Cascade earthquake of 1872 are used to place constraints on its size and location. It appears this earthquake may be slightly larger (magnitude 7.4) and located south and west of the original epicenter determined by Milne.

An Update of Studies of the Bootheel Lineament in the New Madrid Seismic Zone, Southeastern Missouri and Northeastern Arkansas

1992 ◽  
Vol 63 (3) ◽  
pp. 277-284 ◽  
Author(s):  
Eugene S. Schweig ◽  
Ronald T. Marple ◽  
Yong Li
Keyword(s):  
Surface Deformation ◽  
Shear Zones ◽  
Surface Expression ◽  
Seismic Zone ◽  
Near Surface ◽  
Ground Failure ◽  
The North ◽  
Seismogenic Structures ◽  
New Madrid Earthquakes ◽  
New Madrid

Abstract Five trenches across the Bootheel lineament, a possible surface expression of one of the coseismic faults of the great New Madrid earthquakes of 1811 and 1812, indicate that ground failure took place along this 135-km-long feature, probably in 1811 or 1812. The morphology and en echelon pattern of the north-northeast-trending lineament are suggestive of strike-slip displacement on a fault. Three trenches cross portions of the lineament along which liquefied sand was injected. Vertically displaced strata were observed in two of these trenches, but the displacement could be due to collapse caused by the removal of liquefied sand from below. Shear zones exposed in two other trenches do not appear to be directly related to liquefaction and may represent near-surface deformation associated with deeper deformation along potentially seismogenic structures.

scholarly journals Interpretation of lineaments and faults near Summerville, South Carolina, USA, using LiDAR data: implications for the cause of the 1886 Charleston, South Carolina, earthquake

2020 ◽  
Vol 56 ◽  
pp. 073-095
Author(s):  
Ronald T. Marple ◽  
James D. Hurd, Jr.
Keyword(s):  
South Carolina ◽  
Surface Expression ◽  
Late Eocene ◽  
Atlantic Coastal Plain ◽  
Middle Pleistocene ◽  
Lidar Data ◽  
Seismic Zone ◽  
The North ◽  
Seismic Reflection Profiles ◽  
Atlantic Coastal

LiDAR (light detection and ranging) data acquired near Summerville, South Carolina, reveal numerous lineaments trending in various directions across the Middleton Place-Summerville seismic zone (MPSSZ) and surrounding area. These lineaments are defined by linear depressions and stream valleys that are developed within late Eocene to Holocene marine, marginal marine, and fluvial sediments of the Atlantic Coastal Plain. The 40-kmlong, ENE-WSW-oriented Deer Park lineament coincides with the Woodstock epicenter of the 1886 Charleston earthquake, suggesting that the main shock may have occurred along a fault associated with this lineament. The proximity of the 17-km-long, ENE-WSW-oriented Middleton Place lineament to the Middleton Place epicenter suggests that it too may have ruptured in 1886. Several E-W-oriented topographic scarps are also located near the area of modern seismicity, including the 3- to 5-km-long, south-facing McChune and Summerwood scarps. The McChune scarp is aligned with the E-W-trending portion of the Summerville scarp to the west, suggesting that both scarps may be from uplift to the north along the same fault. The McChune scarp and the Otranto and Middleton Place lineaments coincide with faults interpreted from previously acquired seismic-reflection profiles, suggesting that these features are surface expressions of Quaternary faults. Other lineaments east of the MPSSZ are associated with Neogene structural domes, indicating that the interpreted faults along these lineaments have been active during the late Cenozoic. The LiDAR data also revealed a ~350-m dextral offset of a middle Pleistocene beach ridge along the Woodstock fault and a ~20-km-long, NW-SE-oriented lineament to the east (Canterhilllineament) that appears to be the surface expression of the Charleston fault.

Accreted Terranes of the North Cascades Range, Washington: Spokane to Seattle, Washington, July 21–29, 1989

10.1029/ft307 ◽  
1989 ◽  
Author(s):  
R. W. Tabor ◽  
R. A. Haugerud ◽  
E. H. Brown ◽  
R. S. Babcock ◽  
R. B. Miller
Keyword(s):  
North Cascades ◽  
The North ◽  
Accreted Terranes

WTO SUCCESSOR TO GATT

1997 ◽  
Vol 14 (2) ◽  
pp. 172-187
Author(s):  
Arif Sultan
Keyword(s):  
North Africa ◽  
European Economic Community ◽  
Developed Countries ◽  
Economic Community ◽  
Land Area ◽  
The North ◽  
Muslim Countries ◽  
The Pacific ◽  
The World ◽  
The Developed Countries

Within a short span of time a number of economic blocs have emergedon the world horizon. In this race, all countriedeveloped, developingand underdeveloped-are included. Members of the North America FreeTrade Agreement (NAITA) and the European Economic Community(EEC) are primarily of the developed countries, while the EconomicCooperation Organization (ECO) and the Association of South EastAsian Nations (ASEAN) are of the developing and underdevelopedAsian countries.The developed countries are scrambling to create hegemonies throughthe General Agreement on Tariff and Trade (GATT). In these circumstances,economic cooperation among Muslim countries should be onthe top of their agenda.Muslim countries today constitute about one-third of the membershipof the United Nations. There are around 56 independentMuslim states with a population of around 800 million coveringabout 20 percent of the land area of the world. Stretchingbetween Atlantic and the Pacific Oceans, the Muslim Worldstraddles from North Africa to Indonesia, in two major Islamicblocs, they are concentrated in the heart of Africa to Indonesia,in two major blocs, they are concentrated in the heart of Africaand Asia and a smaller group in South and Southeast Asia.'GATT is a multilateral agreement on tariffs and trade establishing thecode of rules, regulations, and modalities regulating and operating internationaltrade. It also serves as a forum for discussions and negotiations ...

INCORPORATION OF METASEDIMENTARY UNITS INTO THE DEEPEST EXPOSED LEVELS OF THE NORTH CASCADES CONTINENTAL ARC: COMPARISON OF THE SKAGIT AND SWAKANE GNEISSES

2017 ◽  
Author(s):  
Kirsten B. Sauer ◽  
◽  
Stacia M. Gordon ◽  
Robert B. Miller ◽  
Jeffrey Vervoort ◽  
...  
Keyword(s):  
North Cascades ◽  
The North ◽  
Continental Arc

scholarly journals A new approach to mapping landslide hazards: a probabilistic integration of empirical and physically based models in the North Cascades of Washington, USA

2019 ◽  
Vol 19 (11) ◽  
pp. 2477-2495
Author(s):  
Ronda Strauch ◽  
Erkan Istanbulluoglu ◽  
Jon Riedel
Keyword(s):  
Statistical Approach ◽  
Joint Probability ◽  
North Cascades ◽  
Physically Based Model ◽  
New Approach ◽  
The North ◽  
Debris Avalanches ◽  
Landslide Hazards ◽  
Infinite Slope Stability Model ◽  
Physically Based

Abstract. We developed a new approach for mapping landslide hazards by combining probabilities of landslide impacts derived from a data-driven statistical approach and a physically based model of shallow landsliding. Our statistical approach integrates the influence of seven site attributes (SAs) on observed landslides using a frequency ratio (FR) method. Influential attributes and resulting susceptibility maps depend on the observations of landslides considered: all types of landslides, debris avalanches only, or source areas of debris avalanches. These observational datasets reflect the detection of different landslide processes or components, which relate to different landslide-inducing factors. For each landslide dataset, a stability index (SI) is calculated as a multiplicative result of the frequency ratios for all attributes and is mapped across our study domain in the North Cascades National Park Complex (NOCA), Washington, USA. A continuous function is developed to relate local SI values to landslide probability based on a ratio of landslide and non-landslide grid cells. The empirical model probability derived from the debris avalanche source area dataset is combined probabilistically with a previously developed physically based probabilistic model. A two-dimensional binning method employs empirical and physically based probabilities as indices and calculates a joint probability of landsliding at the intersections of probability bins. A ratio of the joint probability and the physically based model bin probability is used as a weight to adjust the original physically based probability at each grid cell given empirical evidence. The resulting integrated probability of landslide initiation hazard includes mechanisms not captured by the infinite-slope stability model alone. Improvements in distinguishing potentially unstable areas with the proposed integrated model are statistically quantified. We provide multiple landslide hazard maps that land managers can use for planning and decision-making, as well as for educating the public about hazards from landslides in this remote high-relief terrain.

scholarly journals The evolving response of mesopelagic fishes to declining midwater oxygen concentrations in the southern and central California Current

2018 ◽  
Vol 76 (3) ◽  
pp. 626-638 ◽  
Author(s):  
J Anthony Koslow ◽  
Pete Davison ◽  
Erica Ferrer ◽  
S Patricia A Jiménez Rosenberg ◽  
Gerardo Aceves-Medina ◽  
...  
Keyword(s):  
Baja California ◽  
Southern Oscillation ◽  
Global Climate ◽  
California Current ◽  
Deep Ocean ◽  
Near Surface ◽  
Oxygen Minimum Zones ◽  
The North ◽  
The Pacific ◽  
Oxygen Concentrations

Abstract Declining oxygen concentrations in the deep ocean, particularly in areas with pronounced oxygen minimum zones (OMZs), are a growing global concern related to global climate change. Its potential impacts on marine life remain poorly understood. A previous study suggested that the abundance of a diverse suite of mesopelagic fishes off southern California was closely linked to trends in midwater oxygen concentration. This study expands the spatial and temporal scale of that analysis to examine how mesopelagic fishes are responding to declining oxygen levels in the California Current (CC) off central, southern, and Baja California. Several warm-water mesopelagic species, apparently adapted to the shallower, more intense OMZ off Baja California, are shown to be increasing despite declining midwater oxygen concentrations and becoming increasingly dominant, initially off Baja California and subsequently in the CC region to the north. Their increased abundance is associated with warming near-surface ocean temperature, the warm phase of the Pacific Decadal oscillation and Multivariate El Niño-Southern Oscillation Index, and the increased flux of Pacific Equatorial Water into the southern CC.

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