| Autor: |
Bolton, David C., Shreedharan, Srisharan, McLaskey, Gregory C., Rivière, Jacques, Shokouhi, Parisa, Trugman, Daniel T., Marone, Chris |
| Předmět: |
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| Zdroj: |
Journal of Geophysical Research. Solid Earth; Jun2022, Vol. 127 Issue 6, p1-18, 18p |
| Abstrakt: |
Tectonic faults fail through a spectrum of slip modes, ranging from slow aseismic creep to rapid slip during earthquakes. Understanding the seismic radiation emitted during these slip modes is key for advancing earthquake science and earthquake hazard assessment. In this work, we use laboratory friction experiments instrumented with ultrasonic sensors to document the seismic radiation properties of slow and fast laboratory earthquakes. Stick‐slip experiments were conducted at a constant loading rate of 8 μm/s and the normal stress was systematically increased from 7 to 15 MPa. We produced a full spectrum of slip modes by modulating the loading stiffness in tandem with the fault zone normal stress. Acoustic emission data were recorded continuously at 5 MHz. We demonstrate that the full continuum of slip modes radiate measurable high‐frequency energy between 100 and 500 kHz, including the slowest events that have peak fault slip rates <100 μm/s. The peak amplitude of the high‐frequency time‐domain signals scales systematically with fault slip velocity. Stable sliding experiments further support the connection between fault slip rate and high‐frequency radiation. Experiments demonstrate that the origin of the high‐frequency energy is fundamentally linked to changes in fault slip rate, shear strain, and breaking of contact junctions within the fault gouge. Our results suggest that having measurements close to the fault zone may be key for documenting seismic radiation properties and fully understanding the connection between different slip modes. Plain Language Summary: Tectonic faults can slip rapidly within a few seconds producing intense ground shaking and radiating high‐frequency seismic energy, or they can slip slowly over much longer time scales and emanate weak seismic signals. Understanding the seismic properties of slow and fast earthquakes is a key goal in earthquake science and could have important implications for earthquake hazard. Here, we use laboratory friction experiments instrumented with ultrasonic transducers and document systematic variations in seismic properties for slow and fast laboratory earthquakes. Our data show that both slow and fast laboratory earthquakes radiate measurable high‐frequency energy. Fault slip rate plays a key role in modulating high‐frequency energy and we propose that the origin of this high‐frequency energy originates from the breaking of grain contacts. The high‐frequency characteristics of slow and fast lab earthquakes seem to follow different scaling relationships, which could have important implications for illuminating the connections between slow and fast earthquakes in natural fault systems. Key Points: We document seismic radiation properties of laboratory earthquakes for a spectrum of failure modes from stable sliding to fast stick‐slipThe full spectrum of labquake failure modes radiate measurable high‐frequency energy between 100 and 500 kHzHigh‐frequency energy in slow and fast laboratory earthquakes scales systematically with fault slip rate [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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