UCERF2

UCERF2 stands for the Uniform California Earthquake Rupture Forecast, Version 2. It represents a major effort by the Working Group on California Earthquake Probabilities (WGCEP) to estimate the likelihood and magnitude of earthquakes throughout California over a defined time period, typically 30 years.

UCERF2 builds upon earlier UCERF models and incorporates a range of scientific data and methodologies. This includes data from historical earthquake catalogs, paleoseismic studies of past earthquakes along faults, geodetic measurements of crustal deformation, and analysis of the physical properties of faults.

Key aspects of UCERF2 include:

• Fault-based and time-independent probabilities: It estimates earthquake probabilities based on the known locations and characteristics of faults, assuming that the probability of an earthquake on a particular fault is roughly constant over time.

• Magnitude distribution: It provides probabilities for different earthquake magnitudes, acknowledging that smaller earthquakes are more frequent than larger ones.

• Multiple earthquake rupture scenarios: It considers a wide range of potential earthquake scenarios, including single-fault ruptures and multi-fault ruptures, where an earthquake jumps from one fault to another.

UCERF2 was widely used by government agencies, businesses, and individuals to assess earthquake hazards and risks in California. It informed building codes, emergency planning, and insurance rates. While UCERF2 has been superseded by later versions, such as UCERF3, it remains a significant milestone in earthquake forecasting and a valuable resource for understanding earthquake hazards. The methodologies developed for UCERF2 also laid the foundation for subsequent earthquake forecast models.

The model’s probabilistic approach acknowledges the inherent uncertainty in predicting earthquakes, offering a range of possible outcomes and their associated probabilities rather than a single, definitive prediction.