Probabilistic Estimates of Maximum Seismic Horizontal Ground Acceleration on Rock in Alaska and the Adjacent Continental Shelf

1985 ◽  
Vol 1 (2) ◽  
pp. 285-306 ◽  
Author(s):  
Paul C. Thenhaus ◽  
Joseph I. Ziony ◽  
William H. Diment ◽  
Margaret G. Hopper ◽  
David M. Perkins ◽  
...  
Keyword(s):  
Continental Shelf ◽  
Return Period ◽  
Chukchi Sea ◽  
Poisson Model ◽  
Seismic Source ◽  
Gulf Of Alaska ◽  
Historical Record ◽  
Peak Acceleration ◽  
Ground Acceleration ◽  
Predicted Values

Estimates of ground motion hazard from earthquakes in Alaska and the adjacent continental shelf indicate that, for all the exposure times considered, the predicted values of peak acceleration are highest in the Gulf of Alaska and near the major active strike-slip faults of southern Alaska. The evaluations assume a Poisson model of earthquake occurrence and are based on seismic source zones delineated from regional geologic considerations and the historical record of earthquakes. Calculated peak acceleration values for a return period of 100 years range as high as 0.4 g in the Gulf of Alaska sector between Kodiak and Kayak Islands, are about 0.2 g near Anchorage, and 0.1 g near Fairbanks. Values for most of the rest of the state are estimated to be less than .04 g; however, most of the southern Alaska industrial and population base lies within the 0.2 g contour. For a return period of 500 years, peak accelerations are estimated as high as 0.8 g for parts of southeastern Alaska near the Fairweather fault, 0.6 g or greater for part of the Gulf of Alaska, and are about 0.45 g and 0.2 g, respectively, for the Anchorage and Fairbanks areas. Values of acceleration for a return period of 2,500 years exceed 0.6 g for much of southern Alaska and are 0.8 g or greater near the Fairweather and central Denali faults; estimated values are 0.1 g or greater for nearly all of onshore Alaska and for the continental shelf areas of the Bering Sea, Norton and Kotzebue Sounds, southern Chukchi Sea and southeastern Beaufort Sea.

scholarly journals Exploration and Estimation of Gravel Resource Potential in Southeast Chukchi Sea Continental Shelf off Kivalina, Alaska

2009 ◽  
Vol 27 (4) ◽  
pp. 255-272 ◽  
Author(s):  
A. D'Souza ◽  
S. Bandopadhyay ◽  
S. Naidu ◽  
R. Ganguli ◽  
D. Misra
Keyword(s):  
Continental Shelf ◽  
Chukchi Sea ◽  
Resource Potential

Strong ground motion of mine tremors: Some implications for near-source ground motion parameters

1981 ◽  
Vol 71 (1) ◽  
pp. 295-319
Author(s):  
A. McGarr ◽  
R. W. E. Green ◽  
S. M. Spottiswoode
Keyword(s):  
Ground Motion ◽  
Source Parameters ◽  
Seismic Source ◽  
Shear Velocity ◽  
Recording System ◽  
Ground Acceleration ◽  
Hypocentral Distance ◽  
Earthquake Size ◽  
Mine Tremors ◽  
Stress Drops

abstract Ground acceleration was recorded at a depth of about 3 km in the East Rand Proprietary Mines, South Africa, for tremors with −1 ≦ ML ≦ 2.6 in the hypocentral distance range 50 m < R ≦ 1.6 km. The accelerograms typically had predominant frequencies of several hundred Hertz and peak accelerations, a, as high as 12 g. The peak accelerations show a dependence on magnitude, especially when expressed as dynamic shear-stress differences, defined as σ˜ = ρRa, where ρ is density. For the mine tremors, σ˜ varies from 2 to 500 bars and depends on magnitude according to log σ˜ = 1.40 + 0.38 · ML. Accelerograms for 12 events were digitized and then processed to determine velocity and, for seven events with especially good S/N, displacement and seismic source parameters. Peak ground velocities v ranged up to 6 cm/sec and show a well-defined dependence one earthquake size as measured by ML or by seismic moment, Mo. On the basis of regression fits to the mine data, with −0.76 ≦ ML ≦ 1.45, log Rv = 3.95 + 0.57 ML, where Rv is in cm2/sec, and log Rv = −4.68 + 0.49 log Mo. These regression lines agree excellently with the corresponding data for earthquakes of ML up to 6.4 or Mo to 1.4 × 1026 dyne-cm. At a given value of ML or Mo, a, at fixed R, shows considerably greater variation than v and appears to depend on the bandwidth of the recording system. The peak acceleration at small hypocentral distances is broadly consistent with ρRa = 1.14 Δτrofs/β, where Δτ is stress drop, ro is the source radius, β is shear velocity, and fs is the bandwidth of the recording system. The peak velocity data agree well with Rv = 0.57 βΔτro/μ, where μ is the modulus of rigidity; both expressions follow from Brune's model of the seismic source and were compared with data for events in the size range 5 × 1016 ≦ Mo ≦ 1.4 × 1026 dyne-cm. Measurements of the source parameters indicated that, as for earthquakes, the stress drops for the tremors range from 1 to 100 bars and show no consistent dependence on Mo down to Mo = 5 × 1016 dyne-cm.

scholarly journals Seismic hazard assessment of Iran

1999 ◽  
Vol 42 (6) ◽  
Author(s):  
B. Tavakoli ◽  
M. Ghafory-Ashtiany
Keyword(s):  
Seismic Hazard ◽  
Peak Ground Acceleration ◽  
Grid Point ◽  
Seismic Hazard Assessment ◽  
Earthquake Hazard ◽  
Seismic Source ◽  
Historical Earthquakes ◽  
Earthquake Insurance ◽  
Ground Acceleration ◽  
Seismic Source Models

The development of the new seismic hazard map of Iran is based on probabilistic seismic hazard computation using the historical earthquakes data, geology, tectonics, fault activity and seismic source models in Iran. These maps have been prepared to indicate the earthquake hazard of Iran in the form of iso-acceleration contour lines, and seismic hazard zoning, by using current probabilistic procedures. They display the probabilistic estimates of Peak Ground Acceleration (PGA) for the return periods of 75 and 475 years. The maps have been divided into intervals of 0.25 degrees in both latitudinal and longitudinal directions to calculate the peak ground acceleration values at each grid point and draw the seismic hazard curves. The results presented in this study will provide the basis for the preparation of seismic risk maps, the estimation of earthquake insurance premiums, and the preliminary site evaluation of critical facilities.

scholarly journals Historical record of polychlorinated biphenyls (PCBs) in the continental shelf of the Korea Strait

Chemosphere ◽  
2019 ◽  
Vol 237 ◽  
pp. 124438 ◽  
Author(s):  
Roberta Guerra ◽  
Andrea Pasteris ◽  
Serena Righi ◽  
Gon Ok
Keyword(s):  
Polychlorinated Biphenyls ◽  
Continental Shelf ◽  
Historical Record ◽  
Korea Strait

scholarly journals Peak ground acceleration at surface for Mataram city with a return period of 2500 years using probabilistic method

2018 ◽  
Vol 195 ◽  
pp. 03019
Author(s):  
Rian Mahendra Taruna ◽  
Vrieslend Haris Banyunegoro ◽  
Gatut Daniarsyad
Keyword(s):  
Seismic Hazard ◽  
Return Period ◽  
Peak Ground Acceleration ◽  
Subduction Zones ◽  
Amplification Factor ◽  
Hazard Analysis ◽  
Probabilistic Method ◽  
Seismic Zone ◽  
Ground Acceleration ◽  
Back Arc

The Lombok region especially Mataram city, is situated in a very active seismic zone because of the existence of subduction zones and the Flores back arc thrust. Hence, the peak ground acceleration (PGA) at the surface is necessary for seismic design regulation referring to SNI 1726:2012. In this research we conduct a probabilistic seismic hazard analysis to estimate the PGA at the bedrock with a 2% probability of exceedance in 50 years corresponding to the return period of 2500 years. These results are then multiplied by the amplification factor referred from shear wave velocity at 30 m depth (Vs30) and the microtremor method. The result of the analysis may describe the seismic hazard in Mataram city which is important for building codes.

Seismic design forces for cylindrical tanks on ground

1985 ◽  
Vol 12 (1) ◽  
pp. 12-23
Author(s):  
W. K. Tso ◽  
A. Ghobarah ◽  
S. K. Yee
Keyword(s):  
Radius Ratio ◽  
Hydrodynamic Effect ◽  
Tank Wall ◽  
Base Shear ◽  
Ground Acceleration ◽  
Liquid Storage ◽  
Wall Flexibility ◽  
Flexibility Effect ◽  
Predicted Values ◽  
Cylindrical Tanks

A study is made on the hydrodynamic effect caused by seismic ground motions on the design of cylindrical on-ground liquid-storage tanks. The current techniques for determining the design base shear and overturning moment of the tank are reviewed, first treating the tank wall as rigid and then including the wall flexibility effect. By means of examples, these calculations are compared with those suggested by the National Building Code of Canada (NBCC). In addition, theoretically predicted values are compared with experimental data.It was found that in the case of tanks of high height to radius ratio and small wall thickness to radius ratio, the interaction of the fluid and wall flexibility can cause responses as high as two to three times those calculated based on rigid tank wall assumptions. The range of tank geometries under which the tank can be considered rigid is given. It is shown that the NBCC formula to establish seismic loads for tanks on ground is in general conservative, provided the acceleration ratio in the NBCC formulae takes on the value of maximum peak ground acceleration of the site. Key words: seismic, earthquake, hydrodynamic force, response, cylindrical tanks, design code.

Migration and Feeding of the Gray Whale (Eschrichtius gibbosus)

1962 ◽  
Vol 19 (5) ◽  
pp. 815-838 ◽  
Author(s):  
Gordon C. Pike
Keyword(s):  
British Columbia ◽  
Bering Sea ◽  
Chukchi Sea ◽  
Close Contact ◽  
Gulf Of Alaska ◽  
Bering Strait ◽  
Visual Contact ◽  
Gray Whales ◽  
Baleen Whales ◽  
The Bering Sea

Observations of gray whales from the coasts of British Columbia, Washington, and Alaska are compared with published accounts in order to re-assess knowledge of migration and feeding of the American herd. Source of material is mainly from lighthouses and lightships.The American herd of gray whales retains close contact with the shore during migration south of Alaska. Off Washington and British Columbia the northward migration begins in February, ends in May, and is at a peak during the first two weeks in April; the southward migration occurs in December and January, and is at a peak in late December. Northward migrants stop occasionally to rest or feed; southward migrants are travelling faster and appear not to stop to rest or feed during December and January. Gray whales seen off British Columbia, sometimes in inside protected waters, from June through October, probably remain in this area throughout the summer and fall months.Available evidence suggests that gray whales retain contact with the coast while circumscribing the Gulf of Alaska, enter the Bering Sea through eastern passages of the Aleutian chain, and approach St. Lawrence Island by way of the shallow eastern part of the Bering Sea. Arriving off the coast of St. Lawrence Island in May and June the herd splits with some parts dispersing along the Koryak coast and some parts continuing northward as the ice retreats through Bering Strait. Gray whales feed in the waters of the Chukchi Sea along the Siberian and Alaskan coasts in July, August and September. Advance of the ice through Bering Strait in October initiates the southern migration for most of the herd. In summering areas, in northern latitudes, gray whales feed in shallow waters on benthic and near-benthic organisms, mostly amphipods.There is no evidence to indicate that gray whales utilize ocean currents or follow the same routes as other baleen whales in their migrations. Visual contact with coastal landmarks appear to aid gray whales in successfully accomplishing the 5000-mile migration between summer feeding grounds in the Bering and Chukchi Seas and winter breeding grounds in Mexico.Reconstruction of the migration from all available data shows that most of the American herd breeds and calves in January and February, migrates northward in March, April and May, feeds from June through October, and migrates southward in November and December.

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