Executive summary: The passive seismic survey of the Kaiserstuhl test site was initiated during discussion between partners of the PACIFIC and HiTech AlkCarb H2020 projects in February 2019. The final survey design is similar to an already existing geophysical profile crossing the Kaiserstuhl volcanic edifice surveyed by electrical techniques. A total of 66 3-component nodes were deployed along of the profile, and at the center, above a fault, a few additional nodes were deployed away from the profile to be used for earthquake detection and localization.

The nodes recorded during 25 days in October-November 2019. The raw data was of good quality with stable ambient noise records over the whole duration of acquisition. Cross-correlation showed Rayleigh and Love propagation with weak dispersion, testifying to a homogeneous medium in terms of seismic velocities. However individual correlations showed low signal to noise ratio.

We processed the correlations using a classical method of surface wave tomography, and we jointly inverted Rayleigh and Love wave dispersion curves in order to obtain a 3D S-wave velocity model.

The final Vs model showed three layers parallel to the surface with strong velocity contrasts. This is unexpected in such geological context and could be an edge effect of the inversion near the bottom of the model. Once removed, the Vs Anomaly model shows a homogeneous medium with only weak velocity changes (<5%). A positive anomaly dominates the model and coincides well with the location, size, and shape of the carbonatite pipe found in the existing geological and geophysical models.

Executive summary: Active seismic sources such as explosives, air guns and vibroseis generate energetic P-waves well suited for reflection seismic studies. However, they can have negative environmental impacts and are expensive, both of which have motivated the development of passive seismic methods. Passive seismic methods utilise ambient noise from meteorological and anthropogenic activity. They have been successful for surface wave recovery but extracting body waves for reflection imaging is still a challenge. A key goal of the PACIFIC project is to develop methodologies for extracting body waves from passive seismic data, and for using these body waves for subsurface imaging. This report describes the development of synthetic velocity models that characterise the geological structure and seismic reflectivity at the Marathon Cu-PGE prospect Ontario, Canada. Synthetic seismic signals generated in these models will then be used to develop and test processing procedures for body wave recovery and body wave imaging. A first velocity model consists of two vertical sections obtained by interpolation of lithological contacts identified in drillholes. One section is perpendicular to the dip of the main gabbro intrusion, the other is parallel. A second model is obtained by blind 3D interpolation between drillholes and uses velocities measured on hand samples and drill core. Work in progress uses dedicated geological modelling software to generate a 3D block model that honors geological structures and cross-cutting relationships. A recently acquired downhole acoustic log avoids negative velocity biases from microfractures that can be introduced during depressurisation (e.g. of drill core). This will be used to calibrate a new velocity forward model.

Noise-based ballistic wave passive seismic monitoring – Part 2: surface waves

We develop a new method to monitor and locate seismic velocity changes in the subsurface using seismic noise interferometry. Contrary to most ambient noise monitoring techniques, we use the ballistic Rayleigh waves computed from 30 d records on a dense nodal array located above the Groningen gas field (the Netherlands), instead of their coda waves. We infer the daily relative phase velocity dispersion changes as a function of frequency and propagation distance with a cross-wavelet transform processing. Assuming a 1-D velocity change within the medium, the induced ballistic Rayleigh wave phase shift exhibits a linear trend as a function of the propagation distance. Measuring this trend for the fundamental mode and the first overtone of the Rayleigh waves for frequencies between 0.5 and 1.1 Hz enables us to invert for shear wave daily velocity changes in the first 1.5 km of the subsurface. The observed deep velocity changes (±1.5 per cent) are difficult to interpret given the environmental factors information available. Most of the observed shallow changes seem associated with effective pressure variations. We observe a reduction of shear wave velocity (–0.2 per cent) at the time of a large rain event accompanied by a strong decrease in atmospheric pressure loading, followed by a migration at depth of the velocity decrease. Combined with P-wave velocity changes observations from a companion paper, we interpret the changes as caused by the diffusion of effective pressure variations at depth. As a new method, noise-based ballistic wave passive monitoring could be used on several dynamic (hydro-)geological targets and in particular, it could be used to estimate hydrological parameters such as the hydraulic conductivity and diffusivity.

Executive summary: This report describes events that took place in collaboration with other research projects during the second year of the PACIFIC project, from June 2019 to June 2020. Clustering activities are central to Work Package 7 “Collaboration and clustering with other research initiatives”. To that end, the PACIFIC project has initiated and completed a number of activities with multiple research initiatives. In the second year of the project, clustering activities significantly accelerated, and the earlier links made with other European projects started to yield concrete results and concrete plans for further activities. This report is an update to D7.2 (M12)—Report on joint events with other research projects in the first year.

During this year PACIFIC has established a very strong collaboration with the H2020 project INFACT and this is reflected throughout this report. 

Executive summary: The physical properties of rocks and minerals, particularly their density and elasticity, control the velocitywith which they transmit seismic waves. The acoustic impedance, which is the product of density and seismic velocity, is a useful property to characterize different lithologies. Available data indicates that there are strong contrasts in acoustic impedance between common types of rock and, most importantly, between common rocks and ore minerals. These differences provide a basis for relating passive seismic tomographic models with models based on geological and previously acquired geophysical data.

PACIFIC develops mineral exploration techniques that have a relatively low impact on the environment. This document is an assessment of this impact, but also of the environmental footprint of all activities related to the project. PACIFIC environmental footprint is still significant because of plane travels linked to transnational meetings. Learn more about it by reading the following document.

https://www.pacific-h2020.eu/wp-content/uploads/pacific_documents-on-impact_the-environmental-impact-of-pacific-report-1.pdf 

Executive summary: One of the PACIFIC’s goals is to support the European Innovation Partnership (EIP) on Raw Materials with its aim to translate its mission into concrete actions. To do so, PACIFIC will collaborate closely with the existing, recently finished or future H2020 projects funded under the same or similar topics.
This document includes a concrete plan for clustering with these projects, aiming to facilitate planning of joint online and physical events, sharing results and exchanging on the difficulties encountered.

The clustering plan is divided in three main sections:

• Inventory of relevant H2020 projects:
  • List of the on-going, recently finished and future projects
  • Analysis of the identified projects’ objectives and planned results
  • Assessment of the potential similarities and/or synergies with PACIFIC
  • List of all the projects’ planned events and plan for possible joint events
  • Identification of the potential entry points and established contacts
• Presentation of the common online space facilitating discussions and clustering
• Action list

This clustering plan will be considered as a living document to be reviewed in each General Assembly meeting to monitor the progress made in its implementation and allow for regular updates to take into account the evolving European context and prioritisation.