scholarly journals Crustal movement and strain distribution in East Asia revealed by GPS observations

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Ming Hao ◽  
Yuhang Li ◽  
Wenquan Zhuang
Keyword(s):  
East Asia ◽  
Crustal Deformation ◽  
North China ◽  
Mainland China ◽  
Pacific Plate ◽  
Indian Plate ◽  
Stress Axis ◽  
The Pacific ◽  
Ryukyu Arc ◽  
Gps Observations

AbstractEast Asia is bounded by the Indian plate to the southwest and the Pacific and Philippine plates to the east, and has undergone complex tectonic evolution since ~55 Ma. In this study, we collect and process three sources of GPS datasets, including GPS observations, GPS positioning time series, and published GPS velocities, to derive unified velocity and strain rate fields for East Asia. We observed southward movement and arc-parallel extension along the Ryukyu Arc and propose that the maximum principal stress axis (striking NEE) in North China could be mainly induced by westward subduction of the Pacific plate and the southward movement of the Ryukyu Arc. The large EW-trending sinistral shear zone that bounds North China has been created by eastward movement of South China to the south and westward subduction of the Pacific plate to the north. GPS velocity profiles and strain rates also demonstrate that crustal deformation in mainland China is controlled by northeastward collision of the Indian plate into Eurasia and westward subduction of the Pacific and Philippine Sea plates beneath Eurasia. In particular, the India-Eurasia continental collision has the most extensive impact, which can reach as far as the southern Lake Baikal. The viscous behavior of the subducting Pacific slab also drives interseismic deformation of North China. The crustal deformation caused by Philippine oceanic subduction is small and is limited to the region between the southeast coast of mainland China and Taiwan island. However, the principal compressional strain around eastern Taiwan is the largest in the region.

scholarly journals A Microearthquake Study of the Plate Boundary, North Island, New Zealand

2021 ◽  
Author(s):  
◽  
Martin Everardus Reyners
Keyword(s):  
Plate Boundary ◽  
Pacific Plate ◽  
Focal Mechanisms ◽  
Phase Changes ◽  
Indian Plate ◽  
Depth Range ◽  
The North ◽  
The Pacific ◽  
Deep Activity ◽  
Set Up

<p>The seismicity, structure and tectonics of the North Island plate boundary have been studied by means of a microearthquake traverse oriented in the direction of dip of the subducted Pacific plate and stretching from southern Hawke's Bay to northern Taranaki. The geometry of the top of the Pacific plate is inferred from a band of concentrated microearthquake activity which can be identified with the crust of the plate. The Pacific plate appears to have two knee-like bends, one between the east coast and the Ruahine Range, where the top of the plate is about 25 km deep, the other below the volcanic front, where it is about 70 km deep. The shallower bend and subsequent restraightening of the plate can be related to phase changes in the plate, while the deeper bend can be related to volcanism. Composite focal mechanisms indicate that seaward of its shallower bend the Pacific plate is being loaded by the Indian plate, whereas landward of this bend the Pacific plate is sinking under its own weight. Both composite focal mechanisms and the distribution of microseismicity in the Pacific plate suggest the existence of a major discontinuity striking down the dip of the plate and passing beneath the Tongariro volcanic centre. A conspicuous lack of microseismicity in the Indian plate in the eastern North Island revealed in this study can be related to the plates being unlocked in this region. A feature of the seismicity of the Indian plate in the region of the Wanganui Basin is the concentration of activity in the 25-42 km depth range, shallower activity being largely confined to the northeast edge of the basin, near Mt Ruapehu and Waiouru. Composite focal mechanisms suggest the 25-42 km deep activity reflects stresses set up by locking and unlocking of the plates, while the shallower activity reflects local stresses related to volcanic phenomena.</p>

scholarly journals A Microearthquake Study of the Plate Boundary, North Island, New Zealand

2021 ◽  
Author(s):  
◽  
Martin Everardus Reyners
Keyword(s):  
Plate Boundary ◽  
Pacific Plate ◽  
Focal Mechanisms ◽  
Phase Changes ◽  
Indian Plate ◽  
Depth Range ◽  
The North ◽  
The Pacific ◽  
Deep Activity ◽  
Set Up

<p>The seismicity, structure and tectonics of the North Island plate boundary have been studied by means of a microearthquake traverse oriented in the direction of dip of the subducted Pacific plate and stretching from southern Hawke's Bay to northern Taranaki. The geometry of the top of the Pacific plate is inferred from a band of concentrated microearthquake activity which can be identified with the crust of the plate. The Pacific plate appears to have two knee-like bends, one between the east coast and the Ruahine Range, where the top of the plate is about 25 km deep, the other below the volcanic front, where it is about 70 km deep. The shallower bend and subsequent restraightening of the plate can be related to phase changes in the plate, while the deeper bend can be related to volcanism. Composite focal mechanisms indicate that seaward of its shallower bend the Pacific plate is being loaded by the Indian plate, whereas landward of this bend the Pacific plate is sinking under its own weight. Both composite focal mechanisms and the distribution of microseismicity in the Pacific plate suggest the existence of a major discontinuity striking down the dip of the plate and passing beneath the Tongariro volcanic centre. A conspicuous lack of microseismicity in the Indian plate in the eastern North Island revealed in this study can be related to the plates being unlocked in this region. A feature of the seismicity of the Indian plate in the region of the Wanganui Basin is the concentration of activity in the 25-42 km depth range, shallower activity being largely confined to the northeast edge of the basin, near Mt Ruapehu and Waiouru. Composite focal mechanisms suggest the 25-42 km deep activity reflects stresses set up by locking and unlocking of the plates, while the shallower activity reflects local stresses related to volcanic phenomena.</p>

Lower Yangtze drainage reorganization response to western Pacific Subduction

2020 ◽  
Author(s):  
Ping Wang ◽  
Hongbo Zheng ◽  
Yongdong Wang ◽  
Xiaochun Wei ◽  
Lingyu Tang ◽  
...  
Keyword(s):  
East Asia ◽  
Active Role ◽  
Pacific Plate ◽  
Western Pacific ◽  
Surface Processes ◽  
Silty Clay ◽  
Lithospheric Deformation ◽  
The Pacific ◽  
Lower Yangtze ◽  
Early Cenozoic

&lt;p&gt;The evolution of the longest river in Asia, Yangtze, provides a spectacular example to understand the Cenozoic interaction between tectonic, climate and surface processes. The oldest Yangtze deposits in southeast China, characterized by thick sequence of unconsolidated gravel, sand and silty clay, referred as &amp;#8220;Yangtze Gravel&amp;#8221;, has been recently found in its lower reach and dated back to &gt; 23 Ma, indicating a pre-Miocene establishment of a through-going river. However, the link between river reorganization and tectonic evolution has never been well understood. Far-field effects of the Indian&amp;#8211;Eurasia collision are often invoked to explain the widespread East Asia lithospheric deformations and the opening of the marginal, as well as the through-going of the large rivers. However,&amp;#160; some geological and geophysical investigations challenge this model and suggest that the Pacific Plate subduction beneath Eurasia plays an much more active role in East Asia lithospheric deformation during the Cenozoic. Here, we study the sedimentology, chronology and provenance of the Yangtze Gravel based on 17 stratigraphic sections exposed along the Lower Yangtze River. Our results indicate a braided alluvial system (Paleo-Lower Yangtze) established since early Miocene across the Jianghan Basin, North Jiangsu Basin and East China Sea Shelf Basin. Compared with the Early Cenozoic red-colored, halite-bearing lacustrine deposits, our results indicate a larger tectonically controlled shift from rifting to post-rift down-warping across these basins. During Early Cenozoic, the initial subduction of Pacific Plate may contribute to the back-arc extension and affect the continental deep interior of East Asia many thousands of kilometers from the subduction margin. During Oligocene to Miocene, the ongoing subduction of the Pacific plate produced a stagnant slab that may have significantly triggered the post-rift subsidence and the connection of these basins. The deposition of the &amp;#8220;Yangtze Gravel&amp;#8221; reflect the dynamic response of surface processes to western Pacific subduction in East Asia.&lt;/p&gt;

Cenozoic faulting response of eastern North China to subduction of the Pacific Plate: A case of study of the Luxi Block

2017 ◽  
Vol 52 ◽  
pp. 70-80 ◽  
Author(s):  
Shaojun Li ◽  
Sanzhong Li ◽  
Yongming Wang ◽  
Xiyao Li ◽  
Yanhui Suo ◽  
...  
Keyword(s):  
North China ◽  
Pacific Plate ◽  
The Pacific

Imaging the East Asia using waveform tomography with massive datasets 

2021 ◽  
Author(s):  
Hui Dou ◽  
Sergei Lebedev ◽  
Bruna Chagas de Melo ◽  
Baoshan Wang ◽  
Weitao Wang
Keyword(s):  
East Asia ◽  
Mantle Plume ◽  
Upper Mantle ◽  
High Velocity ◽  
Deep Structure ◽  
Indian Plate ◽  
Low Velocity ◽  
Velocity Anomaly ◽  
The Pacific ◽  
Velocity Anomalies

&lt;p&gt;We present a new shear-wave velocity model of the upper mantle beneath the East Asia, ASIA2021, derived using the Automatic Multimode Inversion technique. We use waveform fits of over 1.3 million seismograms, comprising waveforms of surface waves, S and multiple S waves. &amp;#160;In total, data from 9351 stations and 23344 events constrain ASIA2021, which maps in detail the structure of the lithosphere and underlying mantle beneath the region. Our model reveals deep structure beneath the tectonic units that make up East Asia. It shows agreement with previous models at larger scales and, also, sharper and stronger velocity anomalies at smaller regional scales. High-velocity continent roots are mapped in detail beneath the Sichuan Basin, Tarim Basin, Ordos Block, and Siberian Craton, extending to over 200 km depths. The lack of a high-velocity continental root beneath the Eastern North China Craton (ENCC), underlain, instead, by a low-velocity anomaly, is consistent with the destruction of this Archean nucleus. Strong low-velocity anomalies are mapped within the top 100 km beneath Tibet, Pamir, Altay-Sayan area, and back-arc basins. At greater depths, ASIA2021 shows high-velocity anomalies related to the subducted and underthrusted lithosphere of India beneath Tibet and the subduction of the Pacific and other plates in the upper mantle. In the mantle transition zone (MTZ), we find high-velocity anomalies probably related to deflected subducted slabs or detached portions of ancient continent cratons. In particularly, ASIA2021 reveals separate bodies, probably originating from the Indian Plate lithosphere beneath central Tibet, with one at 100-200 km beneath Songpan-Ganzi Block (SGFB) and the other in the MTZ. A strong low-velocity anomaly extending from the surface to the lower mantle beneath Hainan volcano and South China Sea is consistent with the hypothesis of the Hainan mantle plume. The high-velocity anomaly beneath ENCC in MTZ can be interpreted as a detached Archean continent root. The Pacific Plate subducts beneath the eastern margin of Asia into the MTZ and appears to deflect and extend horizontally as far west as the Songliao Basin. The absence of major gaps in the stagnant slab is consistent with the origin of Changbaishan volcano above being related to the Big Mantle Wedge, proposed previously. The low-velocity anomalies down to ~ 700 km depth beneath the Lake Baikal area suggest a hot upwelling (mantle plume) feeding the widely distributed Cenozoic volcanoes in central and western Mongolia.&lt;/p&gt;

scholarly journals Drought over East Asia: A Review

2015 ◽  
Vol 28 (8) ◽  
pp. 3375-3399 ◽  
Author(s):  
Lixia Zhang ◽  
Tianjun Zhou
Keyword(s):  
East Asia ◽  
North China ◽  
Climate Models ◽  
Summer Precipitation ◽  
Tropical Indian Ocean ◽  
Northern China ◽  
Precipitation Anomaly ◽  
Drought Frequency ◽  
Teleconnection Patterns ◽  
The Pacific

Abstract East Asia is greatly impacted by drought. North and southwest China are the regions with the highest drought frequency and maximum duration. At the interannual time scale, drought in the eastern part of East Asia is mainly dominated by two teleconnection patterns (i.e., the Pacific–Japan and Silk Road teleconnections). The former is forced by SST anomalies in the western North Pacific and the tropical Indian Ocean during El Niño decaying year summers. The precipitation anomaly features a meridional tripolar or sandwich pattern. The latter is forced by Indian monsoon heating and is a propagation of stationary Rossby waves along the Asian jet in the upper troposphere. It can significantly influence the precipitation over north China. Regarding the long-term trend, there exists an increasing drought trend over central parts of northern China and a decreasing tendency over northwestern China from the 1950s to the present. The increased drought in north China results from a weakened tendency of summer monsoons, which is mainly driven by the phase transition of the Pacific decadal oscillation. East Asian summer precipitation is poorly simulated and predicted by current state-of-the-art climate models. Encouragingly, the predictability of atmospheric circulation is high because of the forcing of ENSO and the associated teleconnection patterns. Under the SRES A1B scenario and doubled CO2 simulations, most climate models project an increasing drought frequency and intensity over southeastern Asia. Nevertheless, uncertainties exist in the projections as a result of the selection of climate models and the choice of drought index.

The Double Burden of Malnutrition in East Asia and the Pacific

10.1596/26102 ◽  
2016 ◽  
Author(s):  
Roger Shrimpton ◽  
Nkosinathi Vusizihlobo Mbuya ◽  
Anne Marie Provo
Keyword(s):  
East Asia ◽  
Double Burden ◽  
The Pacific ◽  
Double Burden Of Malnutrition
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