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High-frequency Waveform Simulations for Small Induced Earthquakes in the Near Field

Description: 

Geothermal heat extraction often lies directly beneath cities to reduce heat losses during transport, but placing reservoirs under urban areas raises the risk of induced seismicity through thermal, chemical, and pore-pressure changes in the subsurface. In the Munich region such events are typically small (ML<2.4), yet larger events remain plausible: with a structural PGV tolerance of about 5 mm/s, an event of roughly ML≈2.8 at 3.5 km depth would be sufficient to exceed that threshold. Because these small, shallow earthquakes concentrate energy at high frequencies, realistic hazard assessment requires simulations that reach ~40 Hz — a demanding target for numerical models. Full-waveform 3D simulations are computationally expensive and even for a small region only run up to 10 Hz.

To address this, we adapted the open source software MudPy — which combines Green’s-function based low-frequency synthetics with a stochastic high-frequency simulation — to simulate earthquakes and produce ground-motion time series. It was primarily developed for very large earthquakes i.e. subduction zone ruptures, and we therefore had to adapt it to be capable of simulating small local events. Key adaptation included reduction to a single point source and switching from Saragoni & Hart to Cua envelopes. A challenge is matching both vertical and horizontal acceleration amplitudes and reproducing the high energy pulse waveform across the full frequency band. The adapted workflow can provide a relatively fast, computationally efficient way to generate site-specific scenarios where historical records are sparse but subsurface constraints (e.g., from geothermal surveys) are strong, improving local hazard and engineering assessments.

Session: From Drilling to Ground Shaking: Mechanisms, Monitoring and Mitigation of Induced Earthquakes [Poster]

Type: Poster

Date: 4/17/2026

Presentation Time: 08:00 AM (local time)

Presenting Author: Yara Rossi

Student Presenter: No

Invited Presentation: 

Poster Number: 99

Authors