Possible sources of hydrothermal activity and mud volcanism in southern Sakhalin inferred from local earthquake seismic tomography

2017 ◽  
Vol 18 (5) ◽  
pp. 1943-1958 ◽  
Author(s):  
Ivan Koulakov ◽  
Aleksander S. Serdyukov ◽  
Alexey V. Konovalov ◽  
Valentin I. Mikhailov ◽  
Dmitry A. Safonov ◽  
...  
2019 ◽  
Vol 377 ◽  
pp. 1-16 ◽  
Author(s):  
Yujin Hua ◽  
Shuangxi Zhang ◽  
Mengkui Li ◽  
Tengfei Wu ◽  
Chenyang Zou ◽  
...  

2019 ◽  
pp. 49-66
Author(s):  
E. V. Lebedeva

The characteristic features of the river network, the structure and functioning of the valleys affected by effusive and explosive volcanism, volcano-tectonic phenomena, gas hydrothermal activity and mud volcanism are revealed. It has been established that within flows and covers of effusives, the formation of new streams channels can occur not only due to backward erosion, but also as a result of the collapse of the roof of the near-surface lava tubes, which are actively used by underground runoff. A high erosion rate, a large volume of solid runoff, and a significant role of deflation in the transformation of the fluvial relief are characteristic for regions of domination of explosive activity. There valleys become zones of accumulation of volcanic material, which is gradually processed by mudflow, alluvial, aeolian and other processes. Volcanic-tectonic activity changes the rivers position, direction of streams and morphology of the valleys, leading to numerous reorganizations of the river network, as a result of which the valleys of modern watercourses often consist of uneven-age fragments. Valleys of hydrothermal zones are characterized by the active development of slope processes, which leads to the formation in them not only of sinter terraces, but also numerous landslide ones. Mud volcanic processes periodically lead to the filling and blocking of the valleys with mud breccia flows, which affects both the composition of the alluvium of watercourses and the morphology of the valleys.


2022 ◽  
Author(s):  
B.R. Julian ◽  
G.R. Foulger

ABSTRACT Seismic tomography methods that use waves originating outside the volume being studied are subject to bias caused by unknown structure outside this volume. The bias is of the same mathematical order and similar magnitude as the local-structure effects being studied; failure to account for it can significantly corrupt derived structural models. This bias can be eliminated by adding to the inverse problem three unknown parameters specifying the direction and time for each incident wave, a procedure analogous to solving for event locations in local-earthquake and whole-mantle tomography. The forward problem is particularly simple: The first-order change in the arrival time at an observation point resulting from a perturbation to the incident-wave direction and time equals the change in the time of the perturbed incident wave at the point where the unperturbed ray entered the study volume. This consequence of Fermat’s principle apparently has not previously been recognized. Published teleseismic tomography models probably contain significant artifacts and need to be recomputed using the more complete theory.


Author(s):  
N.P. Yusubov ◽  
◽  
G.M. Alizade ◽  
B.J. Rajabli ◽  
◽  
...  
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