Fault Network Geometry Shapes Earthquake Frictional Behavior in California

Core Concepts

Fault network geometry significantly influences earthquake frictional behavior, with simpler fault geometries facilitating smooth fault creep and complex geometries promoting stick-slip earthquakes.

Abstract

This article presents a new perspective on the factors governing the stability of fault slip, a crucial problem in fault mechanics. The study investigates the link between fault network geometry and surface creep rates in California, USA.

The key findings are:

• Fault groups exhibiting creeping behavior show smaller misalignment in their fault network geometry.
• The surface fault traces of creeping regions tend to be simple, whereas locked regions tend to be more complex.
• The presence of complex fault network geometries results in geometric locking that promotes stick-slip behavior characterized by earthquakes.
• Simpler fault geometries facilitate smooth fault creep.

These observations challenge traditional hypotheses that explain fault creep primarily in terms of fault friction. Instead, the authors propose a new framework where large-scale earthquake frictional behavior is determined by a combination of geometric factors and rheological yielding properties.

The study demonstrates the vital role of large-scale complexities in fault networks on the fault rupture process, going beyond previous lab experiments and numerical models that have focused on the importance of fault geometry and roughness on fault slip behavior.

Stats

Understanding the factors governing the stability of fault slip is a crucial problem in fault mechanics.
Recent lab experiments and numerical models have highlighted the importance of fault geometry and roughness on fault-slip behaviour.
Emerging evidence suggests that large-scale complexities in fault networks have a vital role in the fault-rupture process.

Quotes

"Here we present a new perspective on fault creep by investigating the link between fault-network geometry and surface creep rates in California, USA."
"Our analysis reveals that fault groups exhibiting creeping behaviour show smaller misalignment in their fault-network geometry."
"We propose that the presence of complex fault-network geometries results in geometric locking that promotes stick-slip behaviour characterized by earthquakes, whereas simpler geometries facilitate smooth fault creep."

Key Insights Distilled From

Fault-network geometry influences earthquake frictional behaviour - Nature

by Jaeseok Lee,... at www.nature.com 06-05-2024

https://www.nature.com/articles/s41586-024-07518-6

Deeper Inquiries

How can the insights from this study on fault network geometry be incorporated into earthquake hazard assessment and mitigation strategies?

The insights from this study on fault network geometry can significantly enhance earthquake hazard assessment and mitigation strategies by providing a more comprehensive understanding of fault behavior. By considering the relationship between fault-network geometry and surface creep rates, seismologists and geologists can better predict which regions are more prone to stick-slip behavior and potential earthquake activity. This knowledge can aid in zoning regulations, infrastructure planning, and emergency preparedness efforts. For instance, areas with complex fault geometries that are more likely to experience geometric locking leading to earthquakes could be identified for targeted monitoring and mitigation measures.

What other large-scale factors, beyond fault network geometry, might influence the frictional behavior of fault systems?

In addition to fault network geometry, several other large-scale factors can influence the frictional behavior of fault systems. One crucial factor is the stress distribution within the Earth's crust, which can vary due to tectonic forces, geological structures, and the presence of fluids. The composition and properties of the rocks surrounding the fault, such as their porosity, permeability, and strength, also play a significant role in determining frictional behavior. Furthermore, the presence of pre-existing faults, the rate of strain accumulation, and the overall tectonic setting of the region can all impact fault friction and the likelihood of seismic activity.

Could the principles of fault network geometry and its impact on earthquake behavior be applied to understand the dynamics of other complex natural or engineered systems?

The principles of fault network geometry and its impact on earthquake behavior can indeed be applied to understand the dynamics of other complex natural or engineered systems. For example, similar geometric considerations could be relevant in studying landslides, where the arrangement of slopes and material properties can influence the stability of the system. In the realm of engineering, the insights gained from fault network geometry could be valuable in assessing the behavior of underground structures, such as tunnels or mines, where the interaction of different geological features can affect stability. By applying the lessons learned from fault mechanics to these systems, researchers and engineers can better predict and mitigate potential hazards.