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sensor calibration

Sensor Calibration

Paper on theoretical limits on detection and analysis of small earthquakes

Finally, the paper entitled “Theoretical limits on detection and analysis
of small earthquakes” has been published in Journal of Geophysical Research: Solid Earth. In this paper we investigate theoretical limits on detection and reliable estimates of source characteristics of small earthquakes using synthetic seismograms for shear/tensile dislocations on kinematic circular ruptures and observed seismic noise and properties of several acquisition systems (instrument response, sampling rate). The results presented in the manuscript provide guidelines on detection of small events in various geological environments, along with information relevant to reliable analyses of earthquake source properties.

Reference:

Kwiatek, G., and Y. Ben-Zion (2016), Theoretical limits on detection and analysis of small earthquakes, Journal of Geophysical Research-Solid Earth, 121, doi:10.1002/2016JB012908.

Another paper on Acoustic Emission

We published a paper in European Journal of Environmental and Civil Engineering on analysis of acoustic emission data in fracture and fluid-injection experiments in sandstone. Here is the reference:

Kwiatek, G., Charalampidou, E.-M., Dresen, G., and S. Stanchits (2014). An improved method for seismic moment tensor inversion of acoustic emissions through assessment of sensor coupling and sensitivity to incidence angle. Int. J. Rock Mech. Min. Sci. 65, 153-161, DOI: 10.1016/j.ijrmms.2013.11.005 [ Article Page ]

Abstract:

We performed laboratory experiments on sandstone specimens to study brittle failure and the reactivation of an experimentally produced failure plane induced by pore-pressure perturbations using constant force control in high compressive stress states. Here, we focus on the shear failure of a dry sample and the later on induced fracture plane reactivation due to water injection. Acoustic Emission (AE) monitoring has been used during both experiments. We also used ultrasonic wave velocities to monitor pore fluid migration through the initially dry specimen. To characterise AE source mechanisms, we analysed first motion polarities and performed full moment tensor inversion at all stages of the experiments. For the case of water injection on the dry specimen that previously failed in shear, AE activity during formation of new fractures is dominated by tensile and shear sources as opposed to the fracture plane reactivation, when compressive and shear sources are most frequent. Furthermore, during the reactivation of the latter, compressive sources involve higher compressive components compared to the shear failure case. The polarity method and the moment tensor inversion reveal similar source mechanisms but the latter provides more information on the source components.

Network sensor calibration for retrieving accurate moment tensors of acoustic emissions

Together with Rosalia Davi, Vaclav Vavrycuk, and Elli-Maria Charalampidou we published a manuscript entitled “Network sensor calibration for retrieving accurate moment tensors of acoustic emissions” in the International Journal of Rock Mechanics and Mining Sciences.

The reference:

Davi, R., Vavrycuk, V., E.-M. Charalampidou, and G. Kwiatek (2013). Network sensor calibration for retrieving accurate moment tensors of acoustic emissions. Int. J. Rock Mech. Min. Sci., 62, 59-67, DOI: 10.1016/j.ijrmms.2013.04.004. [ Direct link to the original article ].