ANSS Seminar 2/19: Tim Clements (USGS)

[Barnhart, William D]

Hello Network Seismology Community and Beyond! Mailing List Sign Up Seminar Series Info and Schedule Previous Seminar Recordings Join us for our next seminar! February 19th, 2 pm MT: Tim Clements - USGS - A Ground Motion-based Approach to Earthquake Statistics and Forecasting Click this link to join! Abstract:  We apply earthquake forecasting techniques to ground motion recorded at a single nearby seismometer during an aftershock sequence. The highest resolution “catalog” for ground motion forecasting is a continuous seismogram, where the log10 of ground motion amplitude, A(t), is roughly equivalent to continuous local magnitude. Using continuous amplitudes, rather than just peak amplitude values, has the advantage of not needing to detect or disambiguate phase arrivals from individual earthquakes. We recover time-varying estimates of the Gutenberg-Richter b-value and amplitude of completeness from A(t) using a maximum likelihood approach. Continuous seismograms recover Gutenberg-Richter b-values and the relaxation in ground motion early in an aftershock sequence when real-time earthquake catalogs are most incomplete. In the latter half of the talk, I will discuss the Generate Unsupervised Aftershock Velocity Amplitudes (GUAVA) model, which has been trained on all continuous ground motion time series recorded by the Southern California Seismic Network from 1999-2025 (~30 TB) and all strong-motion recordings from the K-NET and KiK-net arrays in Japan (20 GB for 20,566 events). GUAVA generates suites of ground motion time series, complete with body, surface, and coda waves from aftershocks, autoregressively at a 10 Hz sampling rate. I suggest that GUAVA could be run in real-time using streaming seismic data to forecast ground motion from seconds to minutes after intense shaking occurs. Do you have an idea for a seminar topic? Get in touch with the seminar committee (Will Yeck, Gabrielle Tepp, Fabia Terra, Mairi Litherland, Kyren Bogolub, and Bill Barnhart)