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Multiple SSA Announcements (January 4 - 8)

Date: 01/07/2021

Dear SCEC Community,

Please see below for the following SSA announcements:

1. Towards an Integrated View of Earthquake Gates from Geologic Observations and Numerical Models
2. Beyond Poisson: PSHA at SSA 2021
3. Crustal Stress and Strain and Implications for Fault Interaction and Slip
4. Constructing and Testing Regional and Global Earthquake Forecasts
5. Advances in Earthquake Forecasting and Model Testing


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1. Towards an Integrated View of Earthquake Gates from Geologic Observations and Numerical Models:

Greetings SCEC community,

We would like to invite you to submit an abstract to a multidisciplinary session on earthquake gates that we’re convening at the virtual Seismological Society of America conference to be held April 19-23, 2021. See full description below.

The deadline to submit abstracts is January 13, 2021 at 5 p.m. PST. Find detailed information and other technical sessions here: https://www.seismosoc.org/meetings/submission-system/.

We hope to see you there!

Towards an Integrated View of Earthquake Gates from Geologic Observations and Numerical Models
Fault complexities, such as bends, stepovers and branches, may inhibit earthquake rupture propagation. Numerical modeling, Quaternary slip rate analyses and paleoseismic studies have demonstrated that these structural complexities can act as earthquake gates that exhibit a time-dependent probability of throughgoing rupture. Earthquake gate breaching is sensitive to a variety of parameters, including stress heterogeneities due to prior rupture history, rupture directivity and velocity, rheological properties and fault geometry. Observational records of global earthquake gates remain sparse, and numerical models remain relatively simple compared to real-world fault systems. However, in concert both approaches have advanced our understanding of earthquake gate timing and mechanical behavior considerably.

In this session, we seek to bring together geoscientists from a diverse disciplinary range interested in rupture behavior and timing through fault complexities. We welcome studies using geologic observations, observational seismology and numerical modeling to advance our understanding of earthquake gate behavior. We are particularly interested in studies that synthesize observations from multiple disciplines.

Veronica Prush (veronica.prush@mail.mcgill.ca), McGill University
Alba M. Rodríguez Padilla (arodriguezpadilla@ucdavis.edu), University of California, Davis
Julian Lozos (julian.lozos@csun.edu), California State University, Northridge
Michele Cooke (cooke@umass.edu), University of Massachusetts, Amherst

2. Beyond Poisson: Seismic Hazards and Risk Assessment for the Real Earth:

Traditional probabilistic seismic hazard assessments (PSHA) assume that it is adequate to model earthquakes as temporally random, independent events modeled as a Poisson process. This approach removes the obvious clustering due to aftershocks and swarms; averages or carves out rate variations on short time scales due to natural processes such as volcanoes, as well as short-lived induced seismicity in order to focus on long-term so-called tectonic rates; and may not even use time-dependent mainshock probability variations due to elastic rebound. This may be adequate for long-term (e.g. 50-year) models aimed at low probabilities of exceedance for engineering purposes. The risk industry, typically managing risk transfer contracts from 1 to 5 years, is interested in assessing risk due to processes that act at or affect shorter time scales, from induced seismicity to aftershocks to fault interaction and elastic rebound. Over shorter timescales, when considering the impacts of multiple events and/or at higher probabilities of exceedance, non-Poissonian behavior becomes more important. Recently our ability to describe non-Poissonian behavior has been improved through short-term aftershock and swarm models, models of fluid injection and long-term physics-based simulators. As a result, some national hazard models have incorporated these processes. Many challenges remain. For instance, understanding the impact of incomplete data and non-stationarity on long-term empirical rate estimates is a particularly difficult issue in regions with low seismicity rates and is critical even for traditional PSHA. We encourage contributions that explore how we can better model the broad range of real Earth behavior in different time scales that goes beyond the Poisson process; how we can test those models and include them in hazard and risk assessments; and the societal utility of doing so for a range of users including engineers, the insurance industry, emergency planning and mitigation.

Andrew J. Michael, U.S. Geological Survey (ajmichael@usgs.gov)
Edward H. Field, U.S. Geological Survey (field@usgs.gov)
Delphine D. Fitzenz, RMS (delphine.fitzenz@rms.com)
Matthew C. Gerstenberger, GNS Science (m.gerstenberger@gns.cri.nz)
Andrea L. Llenos, U.S. Geological Survey (allenos@usgs.gov)
Warner Marzocchi, University of Naples Federico (warner.marzocchi@unina.it)
Margarita Segou, British Geological Survey (msegou@bgs.ac.uk)
Tina Wang, University of Otago (twang@maths.otago.ac.nz)

3. Crustal Stress and Strain and Implications for Fault Interaction and Slip:

Please consider submitting abstracts to our session at the upcoming SSA Annual Meeting: "Crustal Stress and Strain and Implications for Fault Interaction and Slip".

Session Description:
This session focuses on (1) the estimation of the state of stress/strain in different phases of earthquake cycle and (2) the analysis of stress/strain distributions at different spatial and temporal scales by soliciting works based on theory, observations, modeling and laboratory experiments.
Contributions are encouraged but not limited to address the following questions: 1) What can we extract from geodetic, geologic, borehole and seismic data regarding the state of stress and strain at regional and local scales?; 2) How are stress and strain distributed in laboratory experiments and nature and how can we bridge the two?; 3) What are the insights from numerical simulations on the state of stress and to what extent can models help in interpreting observations such as earthquakes or slow slip events?; 4) How will spatial stress/strain variations from long-term data compilations improve our knowledge of the motion partitioning across complex fault zone areas, aseismic slip, fault zone structure and earthquake cycles?; 5) How can information on the state of stress/strain be used to improve long-term earthquake forecasting and seismic hazard assessments?

The deadline to submit an abstract is January 13, 2021.
Full meeting information: www.seismosoc.org/annual-meeting/
To submit your abstracts: www.seismosoc.org/meetings/submission-system/

Niloufar Abolfathian, JPL Caltech (niloufar.abolfathian@jpl.nasa.gov)
Thomas H. W. Goebel, University of Memphis
Mong-Han Huang, University of Maryland

4. Constructing and Testing Regional and Global Earthquake Forecasts:

SSA 2021: Constructing and Testing Regional and Global Earthquake Forecasts
Conveners: Maximilian Werner, University of Bristol; David Jackson, University of California, Los Angeles; Danijel Schorlemmer, GFZ German Research Centre for Geosciences

Regional and global earthquake rate and rupture forecasts underpin seismic hazard and risk assessments. They can also serve to test critical hypotheses about seismogenesis, including earthquake nucleation, rupture, interaction and variations of their characteristics with tectonic setting. Global models offer greater testability than regional models because of the larger and more frequent earthquakes. Initiatives to construct and test global models have been led by the Global Earthquake Model (GEM) Foundation, the Southern California Earthquake Center (SCEC), the European H2020 project RISE, re/insurance interests and others. Regional models, on the other hand, benefit from more available and higher resolution datasets, from dense geological records to waveform-similarity enhanced catalogs and long historical catalogs that can be exploited to express bespoke hypotheses, such as spatio-temporal b-value variations, foreshock patterns, Coulomb stress transfer, geodetically detected aseismic slip or fault-based rupture forecasts. Regional and national models are more commonly constructed and can underpin national seismic hazard models and require testing at lower magnitudes to increase test data. We welcome contributions that construct and test probabilistic earthquake forecast models and algorithms from regional via national to global scales. Submissions may include hypothesis-generating research about what controls earthquake potential but should also develop plans for testing prospectively. We also seek submissions that build on vetted earthquake forecasts to construct seismic hazard and risk models, particularly at global scales.

5. Advances in Earthquake Forecasting and Model Testing:

Convener: Maximilian Werner (University of Bristol)
Co-conveners: Warner Marzocchi (University of Naples), Danijel Schorlemmer (GFZ Potsdam)

Vetted probabilistic earthquake forecasts can contribute to more earthquake-resilient societies. Forecasts underpin seismic hazard assessments and thus determine building and life safety. They also provide scientifically sound information about the time-dependence of earthquake potential before, during and after earthquake sequences. To ensure forecasts are trustworthy and to assess the scientific hypotheses underlying the forecasts, models should be tested both retrospectively and prospectively (i.e., against yet-to-be-collected data). For this purpose, the Collaboratory for the Study of Earthquake Predictability (CSEP) provides tools and methods for testing the consistency and precision of earthquake forecasts. This session welcomes contributions that showcase advances in the science of earthquake forecasting and model testing. These can include: new approaches for identifying precursory activity (e.g. b-value variations, aseismic slip transients); forecasts based on empirical machine-learning or physical stress-transfer algorithms; applications of models to earthquake sequences around the globe; advances in model evaluation techniques; or contributions to software tools for model developers. Presentations may also highlight progress of community efforts, such as the EU H2020 project RISE (Real-time earthquake rIsk reduction for a reSilient Europe, www.rise-eu.org) and other initiatives.


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