Paper Towel as a Surrogate Geomaterial for Simulating Natural and Anthropogenic Earthquakes and Their Mitigation
Abstract
Analogue models provide a useful method for experimentally studying earthquake physics. We show a novel approach where we generate laboratory earthquakes using paper towel sheets. In particular, when wetted, the paper changes its resistance and post peak characteristics, mimicking the change of frictional properties of geomaterials under fluid injection. This allows to simulate induced seismicity by wetting the stressed paper and provoke instabilities.
We tested sheets of common paper towel using a tensile testing device for applying constant velocity, which simulates the far-field tectonic displacements. By connecting the sheet with an elastic spring, which represents the elasticity of the rocks surrounding a seismic fault zone, a dynamic instability was observed when the tensile strength of the paper towel was reached. During this event we observed a sudden release of the elastic energy stored in the spring. We then subdivided a large paper sheet into 5 segments (stripes), which could be wetted individually. Following different wetting procedures, we simulated a progressive injection of fluid into distinct fault regions. Each wetting caused an abrupt drop in force, following first the spring slope, and then a re-increase of force under reduced stiffness (see Figure). Knowing the characteristics of the wetting behaviour with and without springs, we can determine the released energy for each wetting step. We observe that in the case where we started wetting at around 20% of the critical stress, the maximum released energy was 126 times smaller than in the dry case. Subsequently releasing the energy in the analogue fault by inducing small seismic events, the largest seismic event was significantly decreased. Using adequate scaling laws, the equivalent earthquake of Mw=5 was reduced to a maximum Mw=4. Under the crucial condition that the analogue fault was initially under low stress, we were able to effectively mitigate the equivalent earthquake hazard. In this regard paper towel served as an interesting new, low-cost surrogate material, which allowed us to explore the limitations of earthquake mitigation and control of induced and natural seismicity.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMMR41F0090B
- Keywords:
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- 3215 Instability analysis;
- MATHEMATICAL GEOPHYSICS;
- 3999 General or miscellaneous;
- MINERAL PHYSICS;
- 5199 General or miscellaneous;
- PHYSICAL PROPERTIES OF ROCKS;
- 8020 Mechanics;
- theory;
- and modeling;
- STRUCTURAL GEOLOGY