How Did the SHARE Project Assess Seismic Hazard in Europe?

Updated

SHARE (Seismic Hazard Harmonization in Europe) was a Collaborative Project under the Seventh Framework Programme of the European Commission. Its main objective was to provide a community-based seismic hazard model for the Euro-Mediterranean region with update mechanisms, establishing new standards in Probabilistic Seismic Hazard Assessment (PSHA) practice through close cooperation among leading European geologists, seismologists, and engineers. The project ended in 2013.

The Assessment Approach

SHARE's assessment rested on a probabilistic framework (PSHA) that combined input from multiple disciplines — geology, seismology, and earthquake engineering — rather than relying on any single data source or national authority.

Key elements of the approach:

  • Cross-border integration framework — The project built a structure for integrating data across national borders, since seismic sources do not stop at country lines.
  • Compiled earthquake and fault data — Relevant earthquake and fault data were gathered and harmonized across the region.
  • Expert elicitation and community feedback — The hazard model was assembled by seeking extensive expert elicitation and participation through multiple community feedback procedures, making it a community-based rather than single-institution product.

The Innovative Weighting Scheme

A distinctive feature of the SHARE assessment was its weighting scheme for input data sets. Rather than treating all data equally, the scheme reflects the importance of each input data set according to its time horizon:

  • For products with longer time horizons, the weighting emphasizes geologic knowledge.
  • For shorter time horizons, it emphasizes seismological data.

This means the relative influence of geology versus seismology shifts depending on the time frame being assessed, rather than applying one fixed blend across all products.

What the Assessment Produced

The project delivered the 2013 Euro-Mediterranean Seismic Hazard Model (ESHM13), a pan Euro-Mediterranean probabilistic seismic hazard assessment. According to the project's own description, ESHM13 consists of:

Feature Detail
Hazard maps More than sixty time-independent ground motion hazard maps
Spectral ordinates From PGA to 4 seconds
Exceedance probabilities 10⁻¹ to 10⁻⁴ yearly probability
Reference rock velocity vs30 = 800 m/s
Earthquake modelling Area sources, active faults, and smoothed background seismicity
Magnitude inclusion All events with Mw ≥ 4.5

How to Cite the Work

If you use SHARE results, the project specifies these citations:

  • SHARE Project: Giardini, D., Woessner J., Danciu L., (2014) Mapping Europe's Seismic Hazard. EOS, 95(29): 261-262.
  • ESHM13 models and results: Woessner, J., Danciu L., D. Giardini and the SHARE consortium (2015), The 2013 European Seismic Hazard Model: key components and results, Bull. Earthq. Eng., doi:10.1007/s10518-015-9795-1.

Outreach materials (official poster, brochures) are referenced at the EFEHR documentation site for specific hazard models covering Europe.

Practical Takeaways

  • SHARE's assessment is a completed, citable reference model (ended 2013), not an ongoing service — treat ESHM13 as a fixed scientific product.
  • Its value lies in harmonization across borders and a transparent weighting rationale tied to time horizon, which you can reference when explaining why long-term and short-term hazard products may differ.
  • For data access, the site lists a "SHARE Portal: Data Access" entry, so the model outputs are intended to be retrievable rather than only published as maps.