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Why (on Earth) should we measure 6 ground motion components … ?

Heiner Igel, Felix Bernauer, Andreas Brotzer, Jean-Paul Montagner, Eleonore Stutzmann, Joachim Wassermann, Sabrina Keil, Le Tang, Shihao Yuan, Chun-Man Liao, Ernst Niederleithinger, & Ulrich Schreiber

Submitted September 11, 2022, SCEC Contribution #12113, 2022 SCEC Annual Meeting Poster #218

… because a 6C point measurement (i.e., three components of translations, three components of rotations) acts like a classic seismic array with 3C sensors (thus interesting particularly in situations in which multiple sensors are difficult to install such as volcanoes, seafloor, boreholes, cities, buildings, planetary objects, etc). 6C data allow the estimation of phase velocities, propagation direction (even in anisotropic media), the separation of wave types, the tracking of seismic sources, the estimation of local subsurface structure, and the removal of tilt-contamination in classic seismometers. In addition, gradient-related observations (strain, rotation) are substantially more sensitive to near receiver structure (relevant for monitoring). In this poster we will report recent progress in applying these hitherto mostly theoretical concepts to real 6C observations including the ROMY ring laser in the Geophysical Observatory Munich as well as data recorded with the broadband rotation sensor BlueSeis-3A. Specific applications include 1) the determination of 1D local velocity structure in urban areas from ambient noise for site characterization, 2) tracking seismic energy generated by cars, 3) estimating source direction at Stromboli volcano, and 4) observing prestress-induced velocity changes in bridges. We also (5) report on the estimation of a rotational low velocity model for planet Earth serving as a target for instrumentation development.

Key Words
rotational ground motions, wavefield gradient

Igel, H., Bernauer, F., Brotzer, A., Montagner, J., Stutzmann, E., Wassermann, J., Keil, S., Tang, L., Yuan, S., Liao, C., Niederleithinger, E., & Schreiber, U. (2022, 09). Why (on Earth) should we measure 6 ground motion components … ?. Poster Presentation at 2022 SCEC Annual Meeting.

Related Projects & Working Groups
Ground Motions