S-wave studies of earthquakes of the North Pacific, Part II: Aleutian Islands

1963 ◽  
Vol 53 (1) ◽  
pp. 59-77
Author(s):  
William Stauder ◽  
Agustin Udias
Keyword(s):  
Aleutian Islands ◽  
Aleutian Island ◽  
Stress System ◽  
S Wave ◽  
The North ◽  
Double Couple ◽  
First Motion ◽  
Good Determination ◽  
The North Pacific

Abstract The polarization of the S wave at stations distributed azimuthally about the source is examined for each of twenty-five Aleutian Island earthquakes. A combination of data from the first motion of P and from the polarization of S is then used to study the focal mechanisms of the earthquakes. This combination of P and S wave data is found to make possible a good determination of the focal mechanism in cases where data from the first motion of P alone do not suffice. The earthquakes are divided into three groups according to three basic patterns of S wave polarization. The first group (fourteen earthquakes) corresponds to a double couple. The second group (five earthquakes) and the third group (six earthquakes) are conformable to conjugate shears and may therefore be explained by single couple sources of opposite moment, respectively. It is shown that a uniform principal stress system predominates in the region and that the axis of greatest compressive stress is normal to the trend of the island arc.

S-Wave studies of earthquakes of the North Pacific, Part I: Kamchatka

1962 ◽  
Vol 52 (3) ◽  
pp. 527-550 ◽  
Author(s):  
William Stauder
Keyword(s):  
Focal Mechanism ◽  
North Pacific ◽  
Vertical Plane ◽  
Point Model ◽  
S Wave ◽  
S Waves ◽  
The North ◽  
Plane Normal ◽  
Double Couple ◽  
The North Pacific

abstract The polarization of S waves at stations distributed azimuthally about the source is examined for each of twenty-three Kamchatka earthquakes of 1950-1960. In nineteen of these earthquakes the P and S wave data are in agreement with a double couple source as the point model of the focal mechanism. The S waves indicate a uniform mechanism which repeats itself from earthquake to earthquake and from which it may be inferred that the axes of greatest and least stress at the foci tend to lie in a vertical plane normal to the trend of the Kamchatka-Kuriles arc. The axis of least stress usually plunges almost vertically under the continent, but may also plunge less steeply, at angles as low as 45 degrees. At least two earthquakes may be represented by a single couple source.

A least squares method for earthquake mechanism determination using S-wave data

1964 ◽  
Vol 54 (6A) ◽  
pp. 2037-2047
Author(s):  
Agustin Udias
Keyword(s):  
Least Squares ◽  
Statistical Evaluation ◽  
Least Squares Method ◽  
Numerical Approach ◽  
Focal Mechanisms ◽  
Least Square ◽  
S Wave ◽  
Double Couple ◽  
Earthquake Mechanism

abstract In this paper a numerical approach to the determination of focal mechanisms based on the observation of the polarization of the S wave at N stations is presented. Least-square methods are developed for the determination of the orientation of the single and double couple sources. The methods allow a statistical evaluation of the data and of the accuracy of the solutions.

Palmaria hecatensis sp. nov. (Rhodophyta, Palmariales) from British Columbia and Alaska with a survey of other Palmaria species

1985 ◽  
Vol 63 (3) ◽  
pp. 474-482 ◽  
Author(s):  
Michael W. Hawkes
Keyword(s):  
British Columbia ◽  
Pacific Ocean ◽  
Geographical Distribution ◽  
North Pacific ◽  
North Pacific Ocean ◽  
Aleutian Islands ◽  
Rocky Shores ◽  
Intertidal Zones ◽  
The North ◽  
The North Pacific

Palmaria hecatensis sp. nov. is described based on material from northern British Columbia. Male gametophytes and tetrasporophytes are thick, coriaceous, flattened blades, linear to lobed in habit and arise from an extensive encrusting basal holdfast. Putative female gametophytes are microscopic multicellular discs. Palmaria hecatensis grows on rocky shores in the midintertidal to lower intertidal zones and has a known geographical distribution from Nootka Island, Vancouver Island, B.C., to Shemya Island in the Aleutian Islands, Alaska. Palmaria hecatensis is compared with other species in the genus and, in addition, another distinctive (and possibly undescribed) Palmaria species from British Columbia and Alaska is discussed, bringing the total number of Palmaria species reported in the North Pacific Ocean to six.

scholarly journals Strengthened Relationship between Tropical West Pacific and Midsummer Precipitation over Northeast China after the Mid-1990s

2020 ◽  
Vol 33 (16) ◽  
pp. 6833-6848
Author(s):  
Tingting Han ◽  
Minghua Zhang ◽  
Botao Zhou ◽  
Xin Hao ◽  
Shangfeng Li
Keyword(s):  
North Pacific ◽  
Northeast China ◽  
Aleutian Islands ◽  
Northwest Pacific ◽  
West Pacific ◽  
The North ◽  
Circulation Anomalies ◽  
The Relationship ◽  
The North Pacific ◽  
Central North Pacific

AbstractThe relationship between the tropical west Pacific (TWP) and East Asian summer monsoon/precipitation has been documented in previous studies. However, the stability for the signals of midsummer precipitation in the TWP sea surface temperature (SST_TWP), which is important for climate variation, has drawn little attention. This study identifies a strengthened relationship between the leading empirical orthogonal function mode (EOF1) of midsummer precipitation over Northeast China (NEC) and the SST_TWP after the mid-1990s. The EOF1 mode shows a significant positive correlation with the SST_TWP for 1996–2016, whereas the relationship is statistically insignificant for 1961–90. Further results indicate that the North Pacific multidecadal oscillation (NPMO) shifts to a positive phase after the 1990s. In the positive NPMO phase, the anomalous circulation over the northeast Pacific expands westward over the central North Pacific–Aleutian Islands region. Concurrently, the SST_TWP-associated wavelike pattern propagates northeastward from the west Pacific to the northwest Pacific and farther to the North Pacific, facilitating the poleward expansion and intensification of the SST_TWP-related circulation anomalies over the North Pacific. Therefore, the SST_TWP has an enhanced influence on NEC precipitation through the modulation of the circulation anomalies over the central North Pacific–Aleutian Islands region after the mid-1990s. Additionally, the tropical anticyclone/cyclone associated with the SST_TWP expands westward to South China, exerting an intensified impact on meridional wind anomalies along eastern China and on moisture transport over NEC. These conditions jointly contribute to the strengthened relationship between the SST_TWP and the EOF1 mode of NEC midsummer precipitation after the mid-1990s.

New species of Poecilosclerida (Demospongiae, Porifera) from the Aleutian Islands, Alaska, USA

Zootaxa ◽  
2006 ◽  
Vol 1155 (1) ◽  
pp. 1 ◽  
Author(s):  
HELMUT LEHNERT ◽  
ROBERT STONE ◽  
WOLFGANG HEIMLER
Keyword(s):  
New Species ◽  
North Pacific ◽  
Aleutian Islands ◽  
The North ◽  
The North Pacific

Five new species of poecilosclerid sponges, Artemisina amlia sp. nov., Coelosphaera oglalai sp. nov., Melonanchora globogilva sp. nov., Tedania kagalaskai sp. nov., and Mycale carlilei sp. nov, are described from the Aleutian Islands, Alaska, from depths ranging between 100–190m and are compared with congeners of the North Pacific Ocean.Keywords: Taxonomy, Porifera, Demospongiae, Poecilosclerida, new species, N-Pacific, Aleutian Islands, Alaska

The Sadiron Lamp of Kamchatka as a Clue to the Chronology of the Aleut

1946 ◽  
Vol 11 (3) ◽  
pp. 202-203
Author(s):  
George I. Quimby
Keyword(s):  
North Pacific ◽  
Cultural Development ◽  
Aleutian Islands ◽  
Bering Strait ◽  
The North ◽  
Kurile Islands ◽  
Cultural Connections ◽  
The North Pacific

Recent studies of trait distributions by Collins, de Laguna, and Heizer, have, in my opinion, demonstrated a cultural connection between southern Alaska, the Aleutian Islands, Kamchatka, and Kurile Islands. These circum- North Pacific cultural connections seem to have been established after settlement of all the areas mentioned and therefore are not properly a part of the problem of man's first entry into America.Southern Alaska, the Aleutian Islands, Kamchatka, and the Kurile Islands form a zone or rim around the North Pacific shores of Asia and America. Along this rim of the North Pacific there seems to have been a drifting of traits and trait complexes, both from America to Asia and from Asia to America. And for the most part, the cultural connections of the circum-North Pacific zone seem to have been rather independent of the diffusions and cultural development of the Bering Strait region.

Combination of P and S data for the determination of earthquake focal mechanism

1971 ◽  
Vol 61 (6) ◽  
pp. 1655-1673 ◽  
Author(s):  
Umesh Chandra
Keyword(s):  
Focal Mechanism ◽  
P Wave ◽  
Wave Polarization ◽  
S Wave ◽  
Polarization Data ◽  
Wave Data ◽  
Earthquake Focal Mechanism ◽  
First Motion ◽  
Depth Ranges

abstract A method has been proposed for the combination of P-wave first-motion directions and S-wave polarization data for the numerical determination of earthquake focal mechanism. The method takes into account the influence of nearness of stations with inconsistent P-wave polarity observations, with respect to the assumed nodal planes. The mechanism solutions for six earthquakes selected from different geographic locations and depth ranges have been determined. Equal area projections of the nodal planes together with the P-wave first-motion and S-wave polarization data are presented for each earthquake. The quality of resolution of nodal plane determination on the basis of P-wave data, S-wave polarization, and the combination of P and S-wave data according to the present method, is discussed.

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