Tandem Code: Modelling the Full Seismic Cycle

Summary

Alis Capri, a professor at LMU Munich and UCSD, describes Tandem — a supercomputing-driven project modeling full seismic cycles and earthquake sequences over centuries. Tandem integrates complex, nonlinear earthquake friction physics with realistic fault geometries and subsurface structure to produce simulations impossible on laptops. The project aims to improve seismic hazard assessment by generating realistic earthquake catalogs, rules for fault-to-fault triggering, and detailed ground-shaking scenarios. It’s open-source, built on a scalable finite-element library optimized for supercomputers, and the team is actively porting Tandem to GPU-based systems and testing it across European and global HPC platforms to boost performance and usability.

Takeaways

• 😀 Tandem is pushing boundaries in simulating large-scale processes, utilizing supercomputers to run models that have never been seen before.
• 🌍 Short-term weather predictions are available, but earthquake predictions are not possible due to a lack of understanding of the underlying physics.
• 🔬 Tandem aims to contribute to earthquake science by improving the understanding of earthquake physics and providing better seismic hazard assessment tools.
• 🛰️ The goal of the project is to model more realistic earthquake catalogs for hazard maps and understand how earthquakes can jump from fault to fault.
• 📉 Current seismic hazard maps are based on limited data points, but Tandem aims to generate more detailed ground shaking models.
• 👩‍🏫 Alis Capri is a guest professor at LMU Munich and an associate professor at UCSD, and is one of the principal investigators of the Tandem project.
• ⚡ Tandem differs from CYO by focusing on earthquake sequences and modeling the full seismic cycle, which spans centuries to thousands of years.
• ⛏️ Tandem's research covers faults that produce both earthquakes and creeping movements, exploring how they relate to each other in the seismic cycle.
• 🔥 Earthquake friction is a complex, nonlinear process and is central to Tandem's focus on earthquake mechanics and modeling fault behavior.
• 💻 Tandem utilizes supercomputing and the Psy library to run efficient simulations on large machines, and it is an open-source project aiming to solve large, complex problems that aren't feasible on personal computers.

Q & A

What is Tandem and how is it different from CYO?

Tandem is a simulation project that focuses on modeling the full seismic cycle, which includes sequences of earthquakes over centuries. Unlike CYO, Tandem is specifically designed to simulate earthquake sequences rather than individual events.

What is the primary challenge in predicting earthquakes?

The primary challenge in predicting earthquakes is the lack of a complete understanding of the physics that drive them. Earthquakes are influenced by complex factors such as friction between fault lines, which are difficult to measure or observe at significant depths.

How does Tandem contribute to seismic hazard assessment?

Tandem contributes by providing more realistic earthquake catalogs, simulating how earthquakes can propagate from one fault to another, and generating detailed ground shaking models that can improve seismic hazard maps.

What does the term 'seismic cycle' refer to in the context of Tandem?

The 'seismic cycle' refers to the long-term process in which a geological fault undergoes multiple earthquakes over hundreds to thousands of years. Tandem aims to model these repeated events and their interactions over time.

What are 'creeping' faults and why are they important for earthquake modeling?

'Creeping' faults are faults that move slowly without producing large earthquakes. They are important because understanding how these faults behave and their connection to larger seismic events is crucial for modeling the full seismic cycle.

What role does friction play in earthquake behavior?

Friction plays a critical role in earthquake behavior. The friction between two sides of a fault can cause stress to accumulate until it is released in an earthquake. This frictional interaction is highly nonlinear and complex, making it a key factor in earthquake dynamics.

What makes the friction involved in earthquakes particularly difficult to study?

The friction involved in earthquakes is difficult to study because it occurs deep within the Earth, at depths of around 20 km, where direct observation and measurement are impossible.

How does Tandem incorporate supercomputing into its simulations?

Tandem leverages supercomputing power to handle the complex and large-scale simulations of seismic cycles. This includes modeling friction, fault geometries, and subsurface structures that would be infeasible on smaller machines.

What is the significance of using GPU hardware in Tandem simulations?

Using GPU hardware in Tandem simulations is crucial for increasing computational efficiency. Modern supercomputers often rely on GPUs to perform large-scale simulations faster, and Tandem is adapting to this hardware to improve performance.

What is the 'Psy' library and why is it used in Tandem?

The 'Psy' library is a well-established finite element library optimized for supercomputing. It is used in Tandem because it is highly efficient on large machines, making it ideal for the complex simulations required for earthquake modeling.