At the last ESC General Assembly in Tel Aviv (August 23-28, 1998) the chairman of the Working Group "Historical earthquake data", Rolf Gutdeutsch, resigned from his position. After discussion within the SC-A "Seismicity" and a recommendation by the Council, a new WG called "Historical Seismology" with Christa Hammerl and Massimiliano Stucchi as chairpersons was established.

The activity of WG "Historical earthquake data", founded in 1986, was mostly devoted discussing methodological aspects. The WG provided a forum where initiatives, at local or national scale, were compared and discussed.

This period coincided with a peak of historical earthquake investigation at international level, supported by consequent funding and involving a relevant number of investigators. The peak was mostly connected with:

• intensive and extensive investigation programmes regarding Nuclear Power Plants (NPP) and other energetic siting programmes (Austria, France, Italy, Spain, Portugal, Morocco, Tunisia, Syria, Turkey, IAEA, etc.)

• intensive and extensive regional (Middle East) or selected time-windows (Antiquity, Middle Ages) investigations

• EC projects (RHISE, BEECD)

• national, post NPP siting projects (Italy, etc.).

Within the frame of these initiatives several thousands of earthquakes were investigated. Most of these initiatives favoured the consolidation of a "true" historical method, assessing the potential of professional historians as providers of determinant contributions. This period determined the transition from a background knowledge based mainly on seismological compilations (Sieberg, Galbis, Perrey, Baratta, Volger, etc.), to the exploitation of primary historical sources. The main goal of this phase dealt with the increase of knowledge of "already known" earthquakes, which included dramatic location and size changes of certain earthquakes and the identification of so-called "fake quakes".

It should be stressed that the huge amount of investigations and results exceeded by far the capacity of the users to exploit them by far. From one hand the quality and amount of data stimulated the investigation of new approaches for the interpretation of historical records in terms of macroseismic intensity and the determination of earthquake parameters from the intensity data points. This led, within the frame of ESC, to the establishment of a new WG on "Macroseismology" and even reflected on the guideline of the new EMS-98 intensity scale.

On the other hand, the results of the new investigation were fed only partially into the parametric earthquake catalogues and, if so, this happened in an erratic way. As a consequence, some earthquakes are still remaining in the catalogues with unrealistic parameters, despite the fact that some good studies might have supplied strong evidence that those parameters are wrong. Some catalogues still include even some fake quakes, which easily escaped elimination although remarkable investigations have already been carried out.

Today, general methodological aspects are well established and widely accepted since the beginning of the '90s: a number of methodological papers and case histories supplied the foundation for historical seismology. Unfortunately these established methods are not always applied in everyday practice.

On the other hand, no significant research projects have been launched, nor approved recently at a national or international level. With a few exceptions the number of investigators devoted to this topic has dramatically dropped.

Historical seismology in Europe needs to better focus its goals and may be find new ones.

Therefore the WG "Historical Seismology" will promote initiatives for improving the potential of historical earthquake investigation.

The programme for the next years will include short- and mid-term goals:

Short-term goals:

• Extensive investigation and preparation of a state-of-the-art of the knowledge on the "large European earthquakes" (details will follow)

Mid-term goals:

• "classical", intensive investigation of key-earthquakes (possibly selected among those whose background is poor, also according to the output of the short term investigation)

• investigation of seismic history of selected sites, also in the view of contributing to solve the problem of data completeness

• damage distribution in urban areas (including information on vulnerability and damage to ordinary and monumental buildings, which can be utilized for estimating seismic ground motion).

• investigation of historical earthquake sequences, for a better calibration of related parameters

• investigation of geological evidence (surface ruptures and other ground effects)

• investigating historical sources potential for detecting "unknown" earthquakes

• integration of and calibration with archaeological data

• contributions concerning historical aspects, including earthquake theories

• etc.

Investigators are invited to make comments and proposals. Topics will be focussed via internet, on the WG website, and in the occasion of Workshops.

Christa Hammerl
Massimiliano Stucchi

Wien, Milano, March 1999