ProjectTitle : OLLIN–Identification (and characterization) of seismogenic faults in populated areas of Latin America and its incorporation into seismic hazard assessment
PI : María Ortuño Candela – Universitat de Barcelona
OLLIN is a project aiming to set up a new collaborative framework between specialists and young researchers from both sides of the Atlantic to improve geological knowledge and seismic hazard assessment (SHA) of two populated regions of Latin America. These are the Transmexican Volcanic belt (TMVB) and the Northern Southamerica Plate Boundary (NSAPB), which extends from Ecuador to Colombia and Venezuela. To do so, three fundamental steps are undertaken; Firstly, data on the seismogenic potential of faults in these areas is gathered, discussed and selected. The most likely fault rupturing mechanisms are discussed, which will lead us to focus the fieldwork on areas which are relevant to SHA but lack information on key seismic parameters (slip rates, segmentation, complex versus simple ruptures, maximum expected earthquakes, etc.). Secondly, the incorporation of that knowledge on seismogenic fault models into the SHA is conducted using existing Fault2SHA tools. This step includes the adaptation of those tools to these specific Latin American settings and the generation of new ones. Finally, results dissemination to society is ensured by the participation of stakeholders from civil protection, geological surveys and other end-users through special meetings, training courses and on-line access that allow to keep track of progress and results.
Understanding how successive earthquakes accrue on faults to produce tectonic landforms is still poorly understood. The way deformation is accommodated throughout the crust, in response to the far-field plate tectonics force imposes at plate boundaries, strongly affects the seismic cycle and may control earthquake triggering and the spatial pattern of fault ruptures. The Apennines range, host of the 2016 seismic sequence (5 shocks Mw5-6.5 over 9 months), is a unique area where the accumulation and release of slip over multiple seismic cycles, over time scales of 1yr-1 Myr and spatial scales of 1m-100km, can be determined. We will combine frontier methodologies in geochronology, remote sensing, geodesy, geophysics, high-resolution topographical data acquisition, seismic hazard modelling, all developed and/or mastered by our teams, to quantitatively constrain how portions of the seismic cycle scale up over multiple cycles to produce the cumulative escarpments we see in the landscape.
In the last months two papers concerning earthquake interactions and probabilistic seismic hazard of the WFZ were published by members of the FAULT2SHA Working Group (Verdecchia et al., 2019, GJI; Valentini et al., 2020, BSSA).
Verdecchia and coauthors used an approach based on physical (coseismic + postseismic Coulomb stress changes) and statistical (probability calculations) to determine if the stress changes due to the youngest paleoevents have significantly modified the present-day probability of occurrence of large earthquakes on each of the segments of the central WFZ. The authors show that regardless of any uncertainties in this approach, Coulomb stress changes strongly affect the time-dependent probability of a large earthquake on the Brigham City, Salt Lake City, and Provo segments. These results indicate that the seismic hazard connected with single-segment ruptures on the central WFZ might be underestimated, if the effects of stress changes are not considered.
Valentini and coauthors assess the impact that the Wasatch fault segmentation model has on seismic hazard by evaluating the time-independent long-term rate of ruptures on the fault that satisfy fault-slip rates and paleoseismic event rates, adapting standard inverse theory used in the Uniform California Earthquake Rupture Forecast (Vers. 3) and implementing a segmentation constraint in which ruptures across primary structural complexities are penalized.
We would like to invite you to submit an abstract to the following Fault2SHA session at the 2020 EGU General Assembly (Vienna, Austria, 3-8 May 2020): Seismic hazard based on paleoseismicity, active faulting and surface deformation data – the challenges of FAULT2SHA. Please find further information about the session and the abstract submission here: https://meetingorganizer.copernicus.org/EGU2020/session/34849 Note: the abstract submission deadline is 15 January 2020. We are looking forward to your contributions.
We finally managed to conclude the Proceedings Book of the meeting, where you can find all the abstracts presented as well as: * a summary of the workshop; * a section about “lessons learned”; * a brainstorming section about key issues and future concerns.
Remember that the key-note lectures are online in the ICM channel:
Fault2SHA launched a contest for the working group logo. Anybody can contribute their creative ideas. All the logo ideas will be discussed in an ExCom meeting and the best logo ideas will be presented for members vote. The artwork receiving the highest score from the votes will be declared the winner and be publicly announced in November 2019. Please submit designs and ideas by 15 October 2019, sending an e-mail to firstname.lastname@example.org.
Great community, great workshop! Thanks to the organizers and the participants of the 4th Fault2SHA Workshop, held in Barcelona on June 3-5, 2019. The final proceedings and link to video contents will be available soon.
Dear Fault2SHA members, we published a new section of our website (http://fault2sha.net/paper-gallery/) aim to be a GIVE-ME-A-REASON-TO-READ list of papers interesting for our Working Group. References are sorted by the year of publication, and alphabetically by the first author. The list will be hopefully updated on a monthly basis. Anyone believe that his/her paper fits the aims and themes of the Fault2SHA WG, please contact the web administrator (email@example.com) to add your titles to the list. Please send us the reference together with a very short summary with the reasons to read it.