Correlation of Kamchatka lithosphere velocity anomalies with subduction processes

2007 ◽  
pp. 97-106 ◽  
Author(s):  
Irina Nizkous ◽  
Edi Kissling ◽  
Irina Sanina ◽  
Larissa Gontovaya ◽  
Valeria Levina
Keyword(s):  
Velocity Anomalies

Magnitude of velocity anomalies prior to earthquakes

1996 ◽  
Vol 101 (B5) ◽  
pp. 11217-11223 ◽  
Author(s):  
Mickaële Le Ravalec ◽  
Yves Gueguen ◽  
Tamaz Chelidze
Keyword(s):  
Velocity Anomalies

Horizontal energy flux of wind-driven intraseasonal waves in the tropical Atlantic by a unified diagnosis

2021 ◽  
Author(s):  
Qingyang Song ◽  
Hidenori Aiki
Keyword(s):  
Energy Flux ◽  
Wave Energy ◽  
Horizontal Distribution ◽  
Kelvin Waves ◽  
Asymmetric Distribution ◽  
Central Basin ◽  
Tropical Atlantic ◽  
Equatorial Wave ◽  
Wave Energy Flux ◽  
Velocity Anomalies

AbstractIntraseasonal waves in the tropical Atlantic Ocean have been found to carry prominent energy that affects interannual variability of zonal currents. This study investigates energy transfer and interaction of wind-driven intraseasonal waves using single-layer model experiments. Three sets of wind stress forcing at intraseasonal periods of around 30 days, 50 days and 80 days with a realistic horizontal distribution are employed separately to excite the second baroclinic mode in the tropical Atlantic. A unified scheme for calculating the energy flux, previously approximated and used for the diagnosis of annual Kelvin and Rossby waves, is utilized in the present study in its original form for intraseasonal waves. Zonal velocity anomalies by Kelvin waves dominate the 80-day scenario. Meridional velocity anomalies by Yanai waves dominate the 30-day scenario. In the 50-day scenario, the two waves have comparable magnitudes. The horizontal distribution of wave energy flux is revealed. In the 30-day and 50-day scenarios, a zonally alternating distribution of cross-equatorial wave energy flux is found. By checking an analytical solution excluding Kelvin waves, we confirm that the cross-equatorial flux is caused by the meridional transport of geopotential at the equator. This is attributed to the combination of Kelvin and Yanai waves and leads to the asymmetric distribution of wave energy in the central basin. Coastally-trapped Kelvin waves along the African coast are identified by along-shore energy flux. In the north, the bend of the Guinea coast leads the flux back to the equatorial basin. In the south, the Kelvin waves strengthened by local wind transfer the energy from the equatorial to Angolan regions.

Non-tomographic Resolution of Small-scale Velocity Anomalies Offshore Netherlands

2014 ◽  
Author(s):  
S. Greenwood ◽  
J.K. Fruehn ◽  
J.K. Fruehn ◽  
R. Lengkeek ◽  
R. Gras ◽  
...  
Keyword(s):  
Small Scale ◽  
Velocity Anomalies

scholarly journals Imaging of the Upper Mantle Beneath Southeast Asia: Constrained by Teleseismic P-Wave Tomography

2020 ◽  
Vol 12 (18) ◽  
pp. 2975
Author(s):  
Huiyan Shi ◽  
Tonglin Li ◽  
Rongzhe Zhang ◽  
Gongcheng Zhang ◽  
Hetian Yang
Keyword(s):  
South China Sea ◽  
Southeast Asia ◽  
Travel Time ◽  
South China ◽  
High Velocity ◽  
Velocity Model ◽  
P Wave ◽  
Deep Part ◽  
Low Velocity ◽  
Velocity Anomalies

It is of great significance to construct a three-dimensional underground velocity model for the study of geodynamics and tectonic evolution. Southeast Asia has attracted much attention due to its complex structural features. In this paper, we collected relative travel time residuals data for 394 stations distributed in Southeast Asia from 2006 to 2019, and 14,011 seismic events were obtained. Then, teleseismic tomography was applied by using relative travel time residuals data to invert the velocity where the fast marching method (FMM) and subspace method were used for every iteration. A novel 3D P-wave velocity model beneath Southeast Asia down to 720 km was obtained using this approach. The tomographic results suggest that the southeastern Tibetan Plateau, the Philippines, Sumatra, and Java, and the deep part of Borneo exhibit high velocity anomalies, while low velocity anomalies were found in the deep part of the South China Sea (SCS) basin and in the shallow part of Borneo and areas near the subduction zone. High velocity anomalies can be correlated to subduction plates and stable land masses, while low velocity anomalies can be correlated to island arcs and upwelling of mantle material caused by subduction plates. We found a southward subducting high velocity body in the Nansha Trough, which was presumed to be a remnant of the subduction of the Dangerous Grounds into Borneo. It is further inferred that the Nansha Trough and the Dangerous Grounds belong to the same tectonic unit. According to the tomographic images, a high velocity body is located in the deep underground of Indochina–Natuna Island–Borneo–Palawan, depth range from 240 km to 660 km. The location of the high velocity body is consistent with the distribution range of the ophiolite belt, so we speculate that the high velocity body is the remnant of thee Proto-South China Sea (PSCS) and Paleo-Tethys. This paper conjectures that the PSCS was the southern branch of Paleo-Tethys and the gateway between Paleo-Tethys and the Paleo-Pacific Ocean. Due to the squeeze of the Australian plate, PSCS closed from west to east in a scissor style, and was eventually extinct under Borneo.

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