scholarly journals Distribution of Holocene Marine Mud and Its Relation to Damage from the 1923 Earthquake Disaster in the Tokyo Metropolitan Area, Japan

Geosciences ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 272
Author(s):  
Susumu Tanabe ◽  
Yoshiro Ishihara ◽  
Toshimichi Nakanishi ◽  
Jan Stafleu ◽  
Freek S. Busschers
Keyword(s):  
Strongly Correlated ◽  
S Wave ◽  
Natural Period ◽  
Incised Valley ◽  
Tokyo Metropolitan Area ◽  
The North ◽  
Kanto Earthquake ◽  
Wooden House ◽  
Valley Fills ◽  
Marine Mud

Tokyo, which is located near the boundary between the North American and Philippine Sea plates, has been frequently struck by large earthquakes throughout the Holocene. The 1923 Taisho Kanto Earthquake is a rare historical earthquake that can be reconstructed in detail because abundant datasets were collected by investigations performed just after the earthquake. We examined 13,000 borehole logs from the Tokyo and Nakagawa lowlands to clarify the distribution and thickness of incised-valley fills and soft marine mud that had accumulated since the Last Glacial Maximum (LGM) on a grid with a resolution of 150 m × 150 m. We compared these datasets with the distribution of wooden house damage ratios caused by the Taisho Kanto Earthquake. Our results showed that the thickness of the soft mud, but not that of the incised-valley fills, was strongly correlated with the wooden house damage ratio. The mud content was >60%, water content was >30%, and S-wave velocity was ca. 100 m/s in the soft Holocene marine mud. The wooden house damage ratio was highest where the soft mud thickness was 20 m, because in those areas, both the soft mud and the wooden houses resonated with a natural period of ca. 1 s.

scholarly journals BROADBAND STRONG MOTION SIMULATION OF THE GREAT 1923 KANTO EARTHQUAKE IN THE TOKYO METROPOLITAN AREA

2007 ◽  
Vol 13 (26) ◽  
pp. 447-450 ◽  
Author(s):  
Shinichi MATSUSHIMA ◽  
Motofumi WATANABE ◽  
Kazuo DAN ◽  
Toshiaki SATO ◽  
Jun'ichi MIYAKOSHI
Keyword(s):  
Metropolitan Area ◽  
Strong Motion ◽  
Motion Simulation ◽  
Tokyo Metropolitan ◽  
Tokyo Metropolitan Area ◽  
Kanto Earthquake ◽  
Strong Motion Simulation

Shear‐wave velocity and density estimation from PS-wave AVO analysis: Application to an OBS dataset from the North Sea

Geophysics ◽  
2000 ◽  
Vol 65 (5) ◽  
pp. 1446-1454 ◽  
Author(s):  
Side Jin ◽  
G. Cambois ◽  
C. Vuillermoz
Keyword(s):  
Wave Velocity ◽  
North Sea ◽  
Random Noise ◽  
P Wave ◽  
S Wave ◽  
Data Set ◽  
Avo Analysis ◽  
The North ◽  
Avo Inversion ◽  
The North Sea

S-wave velocity and density information is crucial for hydrocarbon detection, because they help in the discrimination of pore filling fluids. Unfortunately, these two parameters cannot be accurately resolved from conventional P-wave marine data. Recent developments in ocean‐bottom seismic (OBS) technology make it possible to acquire high quality S-wave data in marine environments. The use of (S)-waves for amplitude variation with offset (AVO) analysis can give better estimates of S-wave velocity and density contrasts. Like P-wave AVO, S-wave AVO is sensitive to various types of noise. We investigate numerically and analytically the sensitivity of AVO inversion to random noise and errors in angles of incidence. Synthetic examples show that random noise and angle errors can strongly bias the parameter estimation. The use of singular value decomposition offers a simple stabilization scheme to solve for the elastic parameters. The AVO inversion is applied to an OBS data set from the North Sea. Special prestack processing techniques are required for the success of S-wave AVO inversion. The derived S-wave velocity and density contrasts help in detecting the fluid contacts and delineating the extent of the reservoir sand.

scholarly journals The biology of Goldsilk Sea Bream (family: Sparidae) from the inshore waters of north coast Kenya

2019 ◽  
Vol 18 (2) ◽  
pp. 77-86
Author(s):  
Rashid O. Anam ◽  
Cosmas N. Munga ◽  
James R. Gonda
Keyword(s):  
Condition Factor ◽  
Well Being ◽  
Feeding Preference ◽  
Growth Patterns ◽  
Sea Bream ◽  
North Coast ◽  
Strongly Correlated ◽  
The North ◽  
Kenyan Coast ◽  
And Migration

The biology of the sparid, Acanthopagrus berda (goldsilk sea bream) was investigated using catch samples obtained from artisanal fishers at selected fish landing sites in the Marereni and Ngomeni fishing areas on the north coast of Kenya. This species has not previously been studied in Kenya although it forms significant proportions of artisanal fish landings and is also a promising aquaculture species. In order to contribute to knowledge of this species, the length-weight relationship, condition factor and feeding preference for prey items were studied in a total of 751 specimens sampled from July 2013 to July 2014. Length-weight relationships for male and female individuals from both fishing areas were strongly correlated (Males: Marereni - R2 = 0.920, Ngomeni - R2 = 0.983; Females: Marereni - R2 = 0.966, Ngomeni - R2 = 0.941). The condition factor of mixed sexes was not significantly different between the two fishing areas (Marereni 2.15 ± 0.08; Ngomeni 2.05 ± 0.02) at p > 0.05. Gut content analysis recorded a total of 5 taxa in the diet (gastropods, molluscs, detritus, crustaceans and fish). The overall sample was dominated by female individuals with an overall sex ratio of females (405 individuals) to males (338 individuals) of 1:0.8 being significantly different at p < 0.05. The species exhibited isometric and positive allometric growth patterns, indicative of the physiological well-being of this species on the north coast of Kenya. Gonadal maturation occurred throughout the year with peaks in July, August and September. However, more work is needed on the biology, distribution, spawning grounds, behavior, and migration patterns along the Kenyan coast. 

scholarly journals Hubungan Rugositas Terumbu Karang terhadap Struktur Komunitas Ikan Corallivor dan Herbivor di Perairan Pemuteran, Bali

2020 ◽  
Vol 3 (1) ◽  
pp. 6
Author(s):  
Nidzar Muhammad Rafly ◽  
I Wayan Gede Astawa Karang ◽  
Widiastuti Widiastuti
Keyword(s):  
Coral Reefs ◽  
Reef Fishes ◽  
Herbivorous Fish ◽  
Strongly Correlated ◽  
Total Abundance ◽  
Underwater Visual Census ◽  
Herbivorous Fishes ◽  
The North ◽  
Fish Feeds ◽  
Abundance And Diversity

Reef fishes are the highest number of organisms that can be found in coral reefs in which the abundance depends on the healthy of this ecosystem. Reef fishes are mainly consisted of corallivorous and herbivorous fish. Corralivorous fish feeds on coral polyps while herbivorous fish feeds on algae. Therefore these fishes are an important indicators in the resilience of coral reefs. Studies showed that its abundance is strongly correlated with reef’s conture (rugosity). Pemuteran waters is one of developing tourists attraction in the north Bali island. However, the data of reef fishes and coral reefs in Pemuteran waters remain limited. Therefore, this research aimed to study the reef` condition and rugosity in Pemuteran waters, also to examine the correlation between reefs fishes and reefs rugosity in this area. There were four stations according to purposive sampling method. Data of corallivorous and herbivorous fishes were collected by using the underwater visual census with a 40 m2 transect. Reef rugosity index were determined by using chain transect method. Results showed that reef rugosity in Pemuteran waters was in the medium to high category. Reef rugosity has strong correlation with the total abundance and diversity of corallivorous fishes. However, reef rugosity was only strong correlated with the total abundance but not with the diversity of herbivorous fishes.

scholarly journals Improving Meteorological Seasonal Forecasts for Hydrological Modeling in European Winter

2020 ◽  
Vol 59 (2) ◽  
pp. 317-332
Author(s):  
Nicky Stringer ◽  
Jeff Knight ◽  
Hazel Thornton
Keyword(s):  
North Atlantic ◽  
Large Scale ◽  
Hydrological Modeling ◽  
Strongly Correlated ◽  
Hydrological Models ◽  
Seasonal Forecasts ◽  
The North ◽  
Ensemble Mean ◽  
The North Atlantic Oscillation ◽  
Correlation Skill

AbstractRecent advances in the skill of seasonal forecasts in the extratropics during winter mean they could offer improvements to seasonal hydrological forecasts. However, the signal-to-noise paradox, whereby the variability in the ensemble mean signal is lower than would be expected given its correlation skill, prevents their use to force hydrological models directly. We describe a postprocessing method to adjust for this problem, increasing the size of the predicted signal in the large-scale circulation. This reduces the ratio of predictable components in the North Atlantic Oscillation (NAO) from 3 to 1. We then derive a large ensemble of daily sequences of spatially gridded rainfall that are consistent with the seasonal mean NAO prediction by selecting historical observations conditioned on the adjusted NAO forecasts. Over northern and southwestern Europe, where the NAO is strongly correlated with winter mean rainfall, the variability of the predicted signal in the adjusted rainfall forecasts is consistent with the correlation skill (they have a ratio of predictable components of ~1) and are as skillful as the unadjusted forecasts. The adjusted forecasts show larger predicted deviations from climatology and can be used to better assess the risk of extreme seasonal mean precipitation as well as to force hydrological models.

Shallow gas features in incised-valley fills (Rı́a de Vigo, NW Spain): a case study

2002 ◽  
Vol 22 (16) ◽  
pp. 2303-2315 ◽  
Author(s):  
S Garcia-Gil ◽  
F Vilas ◽  
A Garcia-Garcia
Keyword(s):  
Nw Spain ◽  
Shallow Gas ◽  
Incised Valley ◽  
Valley Fills
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