التفاصيل البيبلوغرافية
| العنوان: |
Seismic Anisotropy From 6C Ground Motions of Ambient Seismic Noise. |
| المؤلفون: |
Tang, Le1 (AUTHOR) Le.Tang@lmu.de, Igel, Heiner1 (AUTHOR), Montagner, Jean‐Paul2 (AUTHOR), Vernon, Frank3 (AUTHOR) |
| المصدر: |
Journal of Geophysical Research. Solid Earth. Jun2024, Vol. 129 Issue 6, p1-16. 16p. |
| مصطلحات موضوعية: |
*GROUND motion, *MICROSEISMS, *SEISMIC arrays, *TRAVEL time (Traffic engineering), *ANISOTROPY, *EARTHQUAKES, *SEISMIC anisotropy, *SEISMIC waves |
| مصطلحات جغرافية: |
CALIFORNIA |
| مستخلص: |
We propose a new approach capable of measuring local seismic anisotropy from 6C (three‐component translation and three‐component rotation) amplitude observations of ambient seismic noise data. Our recent theory demonstrates that the amplitude ratio of 6C cross‐correlation functions (CCFs) enables retrieving the local phase velocity. This differs from conventional velocity extraction methods based on the travel time. Its local sensitivity kernel beneath the 6C seismometer allows us to study anisotropy from azimuth‐dependent CCFs, avoiding path effects. Such point measurements have great potential in planetary exploration, ocean bottom observations, or volcanology. We apply this approach to a small seismic array at Pin˜ $\widetilde{n}$on Flat Observatory (PFO) in southern California, array‐deriving retrieves rotational ground motions from microseismic noise data. The stress‐induced anisotropy is well resolved and compatible with other tomography results, providing constraints on the origin of depth‐dependent seismic anisotropy. Plain Language Summary: In contrast to the well‐known translational displacement of seismic waves, rotation measures the angle of rotation of a point in a medium as it deforms. Traditionally, the travel time of cross‐correlation functions of translational displacement of ambient seismic noise and its corresponding propagation distance is used to calculate the velocity of the subsurface medium. However, our recent theory shows that the amplitude ratio of translational displacement and rotation allows us to reveal the local velocity of the medium beneath the receiver from ambient seismic noise data and to study anisotropy from earthquake events. This paper points out for the first time that the amplitude observations of 6C cross‐correlation functions of ambient seismic noise provide a new approach to measure the azimuth‐dependent velocity in anisotropic media. Key Points: We show a new approach enabling the extraction of local phase velocity from 6C cross‐correlation functions of ambient noise dataAzimuth‐dependent 6C cross‐correlation functions allow us to study local seismic anisotropy and its depth dependenceLocal anisotropy at Pin˜ $\widetilde{n}$on Flat Observatory is compatible with compression stress, providing constraints on stress‐induced anisotropy [ABSTRACT FROM AUTHOR] |
| قاعدة البيانات: |
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