Computational Methods for Most-Energetic Traveltimes of Seismic Waves

地震波最高能量走时的计算方法

• 批准号: 0107210
• 负责人: Seongjai Kim
• 金额: $ 3.86万
• 依托单位: University of Kentucky Research Foundation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-09-01 至 2004-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0107210&HistoricalAwards=false
• 关键词: Computational; Methods; Most; Energetic; Traveltimes

The work is concerned with the development of computational methods for the most-energetic traveltimes (METTs) of seismic waves and their applications to various physical problems. The METT corresponds to the highest energy level in data and has been recognized as one of most important components for image/inversion processes in highly heterogeneous media. However, METTs often develop discontinuities in wavefronts. Thus, computational principles that have been utilized for the computation of continuous first-arrival traveltimes can hardly be adopted. The upwind direction of the METT is determined by the energy level (amplitudes) of wavefronts and, therefore, the amplitude accuracy is very crucial for a successful METT simulation. Since the transport equation, which solves the amplitude, incorporates the traveltime Laplacian, the traveltime should be solved by a non-oscillatory high-order numerical algorithm which can provide a mechanism for an accurate traveltime Laplacian near the discontinuities. The investigator proposes the development of accurate and efficient algorithms for the METT and the corresponding amplitude in 3D heterogeneous media, incorporating second- and third-order ENO schemes and their local extensions for intersecting wavefronts near discontinuities. A full wavefield solver of negligible numerical dissipation is to be developed and implemented for a numerical verification of the conjecture: the METT can be computed in such a way that the corresponding amplitude is continuous over the whole domain. Applications are planned for the anisotropic METT and realistic geophysical problems such as tomography in oil exploration, earthquake analysis, and shallow seismic reflection. The proposed research subjects are vitally important to energy, economic, and environmental concerns. In particular, the theoretical understanding and numerical algorithms for the METT and the corresponding amplitude will open other promising research areas.For various applications of sound waves traveling through a substance, it is necessary to compute the traveltime of the sound waves. Since the acquired data are dominated by the highest energy levels of the waves, the most reliable results can be obtained by incorporating information from the most-energetic traveltime (METT). The proposal is concerned with the development of accurate and efficient computational algorithms for the METT and applications to important geophysical image processing problems. Image processing methods allow geoscientists to find interesting underground features. In oil exploration, for example, geophysicists first compute images of rock/soil structures and then detect the spots where oil reservoirs are. Thus the oil reservoir detection can be successful only with accurate and well-focused images, for which the newly developed algorithms provide the most useful information. The same arguments can be applied to the shallow sound wave reflection, the image processing techniques for the subsurface not deeper than 100 meters. These techniques have been developed for detailed images; examples can be found in waste-disposal site characterization, archaeological search, and ground security analysis. Many cracks and break-downs on buildings or roads are due to an ignorance or under-estimation of the importance of ground security analysis. The proposed work is also applicable to earthquake analysis. Since a horrible destruction happens with a close relation to the most-energetic components of the earthquake wave, the computation of the METT is necessary for a deeper understanding of the earthquake. The new algorithms are expected to provide an effective mechanism that helps geoscientists simulate seismic ground motion and helps geologists predict earthquake destruction areas, with high accuracy and efficiency. The above mentioned problems are vitally important to energy, economic, and environmental concerns and can be solved more reliably by the proposed work.

这项工作涉及开发地震波的最能量旅行时间（Metts）及其在各种物理问题上的应用。 Mett对应于数据中最高的能级，并被认为是高度异质介质中图像/反转过程最重要的组成部分之一。 然而，梅特经常在波前发展不连续。 因此，很难采用用于计算连续第一次旅行时间的计算原理。 MET的前风方向取决于波前的能级（幅度），因此，幅度精度对于成功的METT模拟至关重要。 由于解决幅度的传输方程融合了旅行时间拉普拉斯，因此旅行时间应通过非振荡的高阶数值算法来解决，该算法可以为不连续性附近准确的旅行时间laplacian提供机制。 研究者提出了Mett的准确有效算法的开发以及3D异质介质中的相应振幅，并结合了二阶和三阶ENO方案及其局部扩展，以与不连续性附近的波兰相交。 可以开发和实施一个可忽略的数值耗散的波场求解器，以进行猜想的数值验证：可以计算Mett以使相应的振幅在整个域上连续的方式计算。 计划在各向异性的Mett和现实的地球物理问题上进行应用，例如石油勘探，地震分析和浅层地震反射中的层析成像。 拟议的研究对象对能源，经济和环境问题至关重要。 特别是，对Mett和相应振幅的理论理解和数值算法将打开其他有希望的研究领域。对于通过物质传播的各种声波应用，有必要计算声波的旅行时间。 由于获取的数据由波的最高能级主导，因此可以通过合并最能量的旅行时间（METT）的信息来获得最可靠的结果。 该提案与Mett的准确有效计算算法的发展有关，并应用于重要的地球物理图像处理问题。 图像处理方法使地球科学家可以找到有趣的地下特征。 例如，在石油勘探中，地球物理学家首先要计算岩石/土壤结构的图像，然后检测储油液所在的斑点。 因此，只有通过精确且注重良好的图像才能成功进行油储层检测，新开发的算法提供了最有用的信息。 相同的参数可以应用于浅声波反射，地下不超过100米的地下的图像处理技术。 这些技术已开发用于详细图像。可以在废物 - 污点场地表征，考古搜索和地面安全分析中找到示例。 建筑物或道路上的许多裂缝和破裂是由于对地面安全分析的重要性的无知或估计所致。 拟议的工作也适用于地震分析。 由于可怕的破坏与地震波的最能量组成部分有着密切的关系，因此对Mett的计算对于对地震的深入了解是必要的。 预计新算法将提供有效的机制，以帮助地球科学家模拟地震地面运动，并帮助地质学家以高准确性和效率来预测地震破坏区域。 上述问题对能源，经济和环境问题至关重要，可以通过拟议的工作更可靠地解决。