Institute Seminars

Title - Relative strengths and deformation mechanisms of amphibole-rich rocks in hot and cold subduction zones

Location - IA 01/473 

Time - 16:15 (also over Zoom)

Summary - Subduction zones host a full spectrum of deformation behaviors and slip rates, from slow aseismic creep to fast catastrophic earthquakes. Between these end-member slip rates, “slow slip events” and “tectonic tremor” occur. Slow slip and tremor (SST) in subduction zones comprise geodetically-detected plate boundary slip at rates exceeding background plate rates, in conjunction with bursts of microseismicity, and can release >90% of convergence-related stress down-dip of the megathrust. SST occurs over an incredible range of Pressure-Temperature conditions, so identifying specific characteristics of an SST-producing environment is challenging. One common denominator is the presence of metamorphosed oceanic crust containing amphibole as a strain-accommodating phase. However, the rheology of amphibole is poorly constrained, so its contribution to steady-state strength and/or slip transients is unknown. In this talk, I will present observations of natural amphibole microstructures from exhumed subduction complexes that record hot and cold subduction geotherms and span a P-T range that encompasses observed SST in active margins, to constrain first-order effects of temperature on operative deformation mechanisms that may favor steady-state creep vs. creep transients. Depending on temperature, the presence/distribution of other phases, and fluid content, amphibole may be capable of accommodating steady-state flow and/or deformation transients over the range of observed SST depths.

Find more about our speaker HERE

Title: "3D Geology for aquifer characterization: from mountain ranges to alluvial basins"

Where? Over Zoom

Summary - Building 3D geological models is a common task in geological studies aiming at natural resources management and hazard assessment. Among them, 3D aquifer models are the base for groundwater flow and transport modelling. The geological history of mountain chains as well as of sedimentary basins originates multiple-scale, nested heterogeneities which must be represented by 3D models. Field data from geological mapping, integrated with remote-sensed surface surveys and geophysical subsurface images, ranging between multiple scales and accuracies, constrain the architectural model. Besides the accurate representation of hydrostratigraphic geometries, an efficient conceptualization of topological and cross-cut relationships between the tectonic, stratigraphic, geomorphological entities is needed: the challenge is translating the geological evolution into simple and flexible modelling rules that should help the collection of efficient input datasets. The method we propose combines field-based geological and modelling approaches with the multi-scale GIS management of the geological dataset. During this talk, we will travel from the rock aquifers of the Alps down to the adjacent multi-layered glaciofluvial and alluvial aquifers of the Po Basin, exploring an approach to 3D hydrostratigraphic reconstructions that can be applied in different geological settings, independently from the scale of the work.

Learn more about our speaker HERE

Dr. Michael Sniehotta

Privat

Title - "The radioactive waste in the Asse II mine and its planned retrieval".

Location - 16:00 s.t, room IA 01/473 and via Zoom

Abstract - The lecture will address the underground storage of radioactive waste in the former rock salt mine Asse at that time, the later decision to retrieve the waste and the measures essential for the planned retrieval since then. These include the stabilization of the severely damaged mine workings, the emergency planning, the exploration of the storage chambers and the considerations on the technology for retrieving the waste from the chambers as well as the underground and surface exploration measures for the new retrieval mine to be opened.

Note: The talk will be given in the German language.

Prof. Bruno Pace

Università di Chieti

Title - Fault-based earthquake rupture forecast: a challenge to model complexities in seismic hazard

Summary - Probabilistic fault-based and time-dependent seismic hazard studies are commonly used to forecast the time between consecutive earthquakes; however, the fault segmentation model and the slip rate variability over time are critical for obtaining accurate results. Recent complex coseismic ruptures (e.g., 2010 Mw 7.1 Canterbury, 2012 Mw 8.6 Sumatra, 2016 Mw 7.8 Kaikōura, 2016 Mw 6.5 central Italy) have shown the need to consider different possible combinations of rupture scenarios. Moreover, geological and paleoseismological observations confirm the slip rate variability, but rarely seismic hazard models consider it. A possible explanation is the presence of networks of active faults, which interact in a complex manner. We present the results of some studies we have done on these topics.

Location - Building IA, Room 01/473 at 16:00