نتایج جستجو برای: period deep crustal exploration
تعداد نتایج: 776957 فیلتر نتایج به سال:
Detailed seismic modeling and imaging of Earth’s deep interior is providing key information about lower-mantle structures and processes, including heat flow across the core-mantle boundary, the configuration of mantle upwellings and downwellings, phase equilibria and transport properties of deep mantle materials, and mechanisms of core-mantle coupling. Multichannel seismicwave analysismethods t...
[1] Analysis of Martian gravity and topography implies that crustal thickness variations created in the earliest evolution of planet have persisted to the present day. Relaxation of crustal thickness variations due to lower crustal flow by thermally activated creep is strongly temperature-dependent and so, for particular crustal rheology and thickness, provides a constraint on thermal evolution...
We analyze a large amount of receiver function data recorded by regional seismic networks of the China Earthquake Administration to estimate crustal structure and deformation beneath the southeast margin of the Tibetan plateau and its surrounding areas. We develop a comprehensive analysis method that facilitates robust extraction of azimuthal seismic anisotropy from receiver function data. The ...
The StarLight program conceptualizes fast interstellar travel via small wafer satellites (wafersats) that are propelled by directed energy. This process is wildly different from traditional space and trades large slow spacecraft for small, fast, inexpensive, fragile ones. main goal of these to gather useful images during their deep journey. We introduce solve some the problems accompany this co...
[1] We have analyzed electron angular distributions recorded near Mars over a period of 7 years in order to constrain the topology of magnetic field lines near Mars. We used 63 million pitch angle distributions of 115 eV electrons measured at 400 km altitudes by the Mars Global Surveyor (MGS) spacecraft and classified them according to their shape. Closed magnetic field lines are associated wit...
Fifteen andesite-dacite stratovolcanoes on the volcanic front of a single segment of the Andean arc show along-arc changes in isotopic and elemental ratios that demonstrate large crustal contributions to magma genesis. All 15 centers lie 90 km above the Benioff zone and 280 _+ 20 km from the trench axis. Rate and geometry of subduction and composition and age of subducted sediments and seafloor...
As an important method to solve sequential decisionmaking problems, reinforcement learning learns the policy of tasks through the interaction with environment. But it has difficulties scaling to largescale problems. One of the reasons is the exploration and exploitation dilemma which may lead to inefficient learning. We present an approach that addresses this shortcoming by introducing qualitat...
Passive seismic interferometry has become very popular in recent years exploration geophysics. However, it not been widely applied marine exploration. The purpose of this study is to investigate the internal structure a quasi-amagmatic portion Southwest Indian Ridge by and examine performance reliability explorations. To reach goal, continuous vertical component recordings from 43 ocean bottom ...
Atmospheric carbon dioxide (CO2) data for the last 420 million years (My) show long-term fluctuations related to supercontinent cycles as well as shorter cycles at 26 to 32 My whose origin is unknown. Periodicities of 26 to 30 My occur in diverse geological phenomena including mass extinctions, flood basalt volcanism, ocean anoxic events, deposition of massive evaporites, sequence boundaries, a...
The shortand long-period body waves of five moderate (M L 5 to 6) earthquakes that took place in the nearshore region of southcentral California between 1969 and 1981 are modeled to obtain the source parameters. Both regional Pnl waveforms and teleseismic P waveforms are used in this analysis. Four of the events are thrust earthquakes with strikes that rotate southwestward as the epicenters mov...
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