scholarly journals Time difference between the 1854 CE Ansei–Tokai and Ansei–Nankai earthquakes estimated from distant tsunami waveforms on the west coast of North America

2022 ◽  
Vol 9 (1) ◽  
Author(s):  
Satoshi Kusumoto ◽  
Kentaro Imai ◽  
Takane Hori
Keyword(s):  
North America ◽  
San Francisco ◽  
West Coast ◽  
Tide Gauge ◽  
Historical Earthquakes ◽  
Time Difference ◽  
The West ◽  
Origin Time ◽  
Significant Difference ◽  
Tsunami Waveforms

AbstractWe estimated the time difference between the 1854 CE Ansei–Tokai and Ansei–Nankai earthquakes from tidal records of two tide gauge stations (San Francisco and San Diego) on the west coast of North America. The first signals of the Ansei–Tokai tsunami were apparent, whereas those of the Ansei–Nankai tsunami were obscured by the later waves of the Ansei–Tokai tsunami. Waveforms of the Ansei–Nankai tsunami simulated with nonlinear dispersive wave theory by assuming an origin time of 07:00 GMT on 24 December arrived earlier than in the observations. The normalized root mean square and the misfit between the simulated and observed waveforms of the Ansei–Nankai tsunami showed a time difference between them of approximately 0.4 h. This finding suggests that the actual origin time of the Ansei–Nankai tsunami was approximately 07:24 GMT on 24 December. A previous study estimated the origin time of the Ansei–Tokai tsunami to be about 00:30 GMT on 23 December. Thus, we concluded that the time difference between the 1854 CE Ansei–Tokai and Ansei–Nankai tsunamis was 30.9 h. Despite the significant difference in the time resolution between the seasonal timekeeping system used in Japan in 1854 and waveform digitization, our result is roughly in agreement with historical descriptions of the tsunamis, suggesting that such information can be effectively used to determine the origin times of historical earthquakes.

scholarly journals Time Difference Between the 1854 CE Ansei–Tokai and Ansei–Nankai Earthquakes Estimated from Distant Tsunami Waveforms on the West Coast of North America

2021 ◽  
Author(s):  
Satoshi Kusumoto ◽  
Kentaro Imai ◽  
Takane Hori
Keyword(s):  
North America ◽  
San Francisco ◽  
West Coast ◽  
Tide Gauge ◽  
Historical Earthquakes ◽  
Time Difference ◽  
The West ◽  
Origin Time ◽  
Significant Difference ◽  
Tsunami Waveforms

Abstract We estimated the time difference between the 1854 CE Ansei–Tokai and Ansei–Nankai earthquakes from tidal records of two tide gauge stations (San Francisco and San Diego) on the west coast of North America. The first signals of the Ansei–Tokai tsunami were apparent, whereas those of the Ansei–Nankai tsunami were obscured by the later waves of the Ansei–Tokai tsunami. Waveforms of the Ansei–Nankai tsunami simulated with non-linear dispersive wave theory by assuming an origin time of 07:00 GMT on 24 December arrived earlier than in the observations. The normalized root mean square and the misfit between the simulated and observed waveforms of the Ansei–Nankai tsunami showed a time difference between them of approximately 0.4 h. This finding suggests that the actual origin time of the Ansei–Nankai tsunami was approximately 07:24 GMT on 24 December. A previous study estimated the origin time of the Ansei–Tokai tsunami to be about 00:30 GMT on 23 December. Thus, we concluded that the time difference between the 1854 CE Ansei–Tokai and Ansei–Nankai tsunamis was 30.9 h. Despite the significant difference in the time resolution between the seasonal timekeeping system used in Japan in 1854 and waveform digitization, our result is roughly in agreement with historical descriptions of the tsunamis, suggesting that such information can be effectively used to determine the origin times of historical earthquakes.

Origin Time of the 1854 Ansei–Tokai Tsunami Estimated from Tide Gauge Records on the West Coast of North America

2020 ◽  
Vol 91 (5) ◽  
pp. 2624-2630 ◽  
Author(s):  
Satoshi Kusumoto ◽  
Kentaro Imai ◽  
Ryoko Obayashi ◽  
Takane Hori ◽  
Narumi Takahashi ◽  
...  
Keyword(s):  
North America ◽  
San Francisco ◽  
Local Time ◽  
West Coast ◽  
San Diego ◽  
Arrival Time ◽  
Tide Gauge ◽  
The West ◽  
Origin Time ◽  
Tsunami Signal

Abstract We estimated the origin time of the 1854 Ansei–Tokai tsunami from the tsunami waveforms recorded at three tide gauge stations (Astoria, San Francisco, and San Diego) on the west coast of North America. The tsunami signal is apparent in the San Francisco and San Diego records, and the arrival time was 0–1 p.m. Greenwich Mean Time (GMT) on 23 December 1854, whereas the tsunami signal of Astoria is ambiguous, and the arrival time could not be determined from the waveform. The simulated waveforms on the basis of nonlinear dispersive wave theory by assuming an origin time of 0 a.m. GMT on 23 December arrived earlier than the observations. Cross-correlation functions between the observed and simulated waveforms recorded at San Francisco and San Diego showed a time gap between them of approximately 30 min. Based on these results, we concluded that the origin time of the 1854 Ansei–Tokai tsunami was approximately 00:30 a.m. GMT or 09:46 local time on 23 December. Our result is roughly consistent with reports by a Russian frigate anchored in Shimoda Bay, ranging the earthquake between 09:00 and 09:45 and the tsunami between 09:30 and 10:00. The earthquake was also reported in historical Japanese documents ranging from 8 and 10 o’clock in local time.

scholarly journals Potential Ocean Dispersal of Cordgrass (Spartina spp.) from Core Infestations

2013 ◽  
Vol 6 (2) ◽  
pp. 250-259 ◽  
Author(s):  
Vanessa H. Morgan ◽  
Mark D. Sytsma
Keyword(s):  
North America ◽  
San Francisco ◽  
West Coast ◽  
Ocean Currents ◽  
Willapa Bay ◽  
The West ◽  
Kodiak Island ◽  
Propagule Dispersal ◽  
Release Location ◽  
North And South

AbstractNonnative Spartina species (cordgrasses) are widely distributed along the West Coast of North America, but have not invaded all bays with susceptible habitat. We used drift cards to assess the patterns and rates of potential Spartina propagule dispersal by ocean currents from estuaries with significant populations of one or more Spartina species. Cards were released monthly for 1 yr from Willapa Bay, Washington; Humboldt Bay, California; and San Francisco Bay, California; with recovery information reported by volunteers. Recovery rates averaged 37% for all release sites. Cards were commonly recovered close to their bay of release but were repeatedly found hundreds of kilometers both north and south of their release location. Cards most generally traveled northward from the release sites. Cards from Humboldt and Willapa bays were commonly recovered along the British Columbia coast, particularly in the winter. Cards released from Humboldt Bay were found farthest from their release sites. One card from Humboldt Bay traveled 2,800 km to Kodiak Island, Alaska. The timing of seed production, combined with prevailing currents, puts bays currently uninfested by Spartina at risk of repeated propagule loading by ocean currents. A coordinated coast-wide strategy for eradication of all nonnative Spartina will be critical to the success of individual bay-wide eradication efforts.

scholarly journals Nonlinear absolute sea-level patterns in the long-term-trend tide gauges of the West Coast of North America

2020 ◽  
Vol 9 (1) ◽  
pp. 382-397
Author(s):  
Alberto Boretti
Keyword(s):  
North America ◽  
Sea Level ◽  
West Coast ◽  
Tide Gauge ◽  
Relative Rate ◽  
Tide Gauges ◽  
The West ◽  
The Absolute ◽  
Long Term Trend

AbstractThe research issue of which are the present relative and absolute rates of rise and accelerations for North America is here addressed. The data of the 20 long-term-trend (LTT) tide stations of the West Coast of North America with more than 80 years of recorded data are shown. The absolute rates of rise are computed by considering the absolute vertical velocity of Global Navigation Satellite System (GNSS) antennas near the tide gauges, and the relative rate of sea-level rise from the tide gauge signals. The 20 LTT stations along the West Coast of North America show an average relative rate of rise of -0.38 mm/yr., an average acceleration of +0.0012 mm/yr2, and an average absolute rate of rise of +0.73 mm/yr. This is the first paper publishing a comprehensive survey of the absolute sea-level rates of rise along the West Coast of North America using the reliable information of relative sea-level rates of rise from LTT tide gauges plus the absolute subsidence rates from different GNSS antennas close to the tide gauge installations.

scholarly journals Are tidal predictions a good guide to future extremes? – a critique of the Witness King Tides Project

2020 ◽  
Author(s):  
John Hunter
Keyword(s):  
North America ◽  
West Coast ◽  
East Coast ◽  
Tide Gauge ◽  
Tide Gauge Records ◽  
The West ◽  
The World ◽  
The Usa ◽  
Good Guide ◽  
Using Data

Abstract. An analysis of the viability of the Witness King Tides Project (hereafter called WKT) using data from the GESLA-2 database of quasi-global tide-gauge records is described. The results indicate regions of the world where WKT should perform well (e.g. the west coast of the USA) and others where it would not (e.g. the east coast of North America). Recommendations are made both for assessments that should be made prior to a WKT project, and also for an alternative to WKT projects.

The Lower Jurassic phosphorites of southeastern British Columbia and terrane accretion to western North America

1989 ◽  
Vol 26 (8) ◽  
pp. 1612-1616 ◽  
Author(s):  
T. P. Poulton ◽  
J. D. Aitken
Keyword(s):  
British Columbia ◽  
North America ◽  
Oceanic Crust ◽  
West Coast ◽  
Cold Water ◽  
Lower Jurassic ◽  
Depositional Model ◽  
Western North America ◽  
The West ◽  
Terrane Accretion

Sinemurian phosphorites in southeastern British Columbia and southwestern Alberta conform with the "West Coast type" phosphorite depositional model. The model indicates that they were deposited on or near the Early Jurassic western cratonic margin, next to a sea or trough from which cold water upwelled. This suggests that the allochthonous terrane Quesnellia lay well offshore in Sinemurian time. The sea separating Quesnellia from North America was partly floored by oceanic crust ("Eastern Terrane") and partly by a thick sequence of rifted, continental terrace wedge rocks comprising the Purcell Supergroup and overlying Paleozoic sequence. This sequence must have been depressed sufficiently that access of upwelling deep currents to the phosphorite depositional area was not impeded.

scholarly journals A taxonomic review of pterotracheoid gastropod mollusks from California Current waters off the west coast of North America

Zoosymposia ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 147-150
Author(s):  
ROGER R. SEAPY
Keyword(s):  
North America ◽  
West Coast ◽  
Morphological Characteristics ◽  
California Current ◽  
Single Species ◽  
The West ◽  
Taxonomic Review ◽  
Gastropod Mollusks ◽  
Taxonomic Characterization

Taxonomic characterization of pterotracheoid gastropods, morphological characteristics and occurrence in California Current waters are reviewed. Single species of atlantid (Atlanta californiensis) and carinariid (Carinaria japonica) from these waters are described and illustrated.

scholarly journals The Timeless African and the Versatile Indian in Seventeenth-Century Travelogues

2005 ◽  
Vol 14 (1) ◽  
pp. 23-44
Author(s):  
Michel Duquet
Keyword(s):  
Seventeenth Century ◽  
North America ◽  
American Indian ◽  
West Coast ◽  
Tropical Environment ◽  
The West ◽  
The North ◽  
Native Populations ◽  
French And English ◽  
North American Indian

Abstract The seventeenth century saw the early stages of significant trading on the west coast of Africa as well as the establishment of permanent settlements in North America by Dutch, French and English explorers, merchants, colonists and missionaries in a period marked by the imperial contest that had been set in motion on the heels of the discovery of America in 1492. The travelers who wrote about their voyages overseas described at length the natives they encountered on the two continents. The images of the North American Indian and of the African that emerged from these travel accounts were essentially the same whether they be of Dutch, French or English origin. The main characteristic in the descriptions of African native populations was its permanent condemnation while representations of the Indian were imbued with sentiments ranging from compassion, censure and admiration. The root causes for this dichotomy were the inhospitable and deadly (to Europeans) tropical environment of Africa’s West Coast and the growing knowledge of local societies that Europeans acquired in North America. The analysis of the contrasting images of natives on both sides of the Atlantic and the context within which they were produced are the focus of the paper.

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