Marchenko imaging based on self-adaptive traveltime updating

Marchenko imaging obtains the subsurface reflectors using one-way Green’s functions,which are retrieved by solving the Marchenko equation.This method generates an image that is free of spurious artifacts due to internal multiples.The Marchenko imaging method is a target-oriented technique;thus,it can image a user specified area.In the traditional Marchenko method,an accurate velocity model is critical for estimating direct waves from imaging points to the surface.An error in the velocity model results in the inaccurate estimation of direct waves.In turn,this leads to errors in computation of one-way Green’s functions,which then affects the final Marchenko images.To solve this problem,in this paper,we propose a self-adaptive traveltime updating technique based on the principle of equal traveltime to improve the Marchenko imaging method.The proposed method calculates the time shift of direct waves caused by the error in the velocity model,and corrects the wrong direct wave according to the time shift and reconstructs the correct Green’s functions.The proposed method improves the results of imaging using an inaccurate velocity model.By comparing the results from traditional Marchenko and the new method using synthetic data experiments,we demonstrated that the adaptive traveltime updating Marchenko imaging method could restore the image of geological structures to their true positions.

On the Right to Life

The COVID-19 pandemic is not only the first public health emergency that human beings are jointly faced with, but also the first time that mankind is confronted with a tremendous disaster together To face lives rationally in a pandemic, "criteria" and "rules" need to be regulated by reason Amid such a catastrophe, we need to reply to questions such as whether the right to life should take precedence over other rights and whether each individual’s life should be treated equally, the answers to which, of course, are definitely positive With the advent of a risk society, public health emergencies are no longer occasional incidents Instead, they might become a more frequent problem in the development of modernity In the community with a shared future for human beings, to protect human rights, the humanitarian spirit, the principle of equality and the idea of justice by playing the role of the state will become a new normal in safeguarding the right to life.