Task 3 - Improving the supporting data sets

The qualified WF compiled by means of Task 1 and Task 2 represents the situation "frozen" at the time of publication of each PEC.
The goal of Task 3 is to retrieve and - mostly - to improve the supporting data sets; it will be achieved according to two categories of earthquakes:

earthquakes for which new studies
have been published after the
publication of the referring PEC
  3a - to retrieve and evaluate the available roots
earthquakes for which no roots
of acceptable level are available
  3b - to investigate some of them (according to priority criteria) for producing BEECD roots

  This investigation is summarised in the investigation reports (App. D1 to D8). Available roots
As most of the published PEC date back to the 80's, the situation today is that most of the studies, published or unpublished, produced after the publication of the input PEC, have not been used as new roots, except for a few cases. Therefore, in the first phase of the project partners inventoried earthquake studies published in the last ten to fifteen years and found out which ones of them provided "new roots" of better quality than the roots supporting the corresponding entries in the BEECD Working File. Obviously, little contribution came from the countries whose adopted input PEC is more recent.

The new, available roots were produced by a number of authors or agencies and reported according to varied format. To make them comparable one to another, a short report was designed containing:

In all, about 1035 new, available roots were retrieved.

Some case histories are presented in App. E1.1 to E1.3.

BEECD roots
After inventorying the new, available roots, the main problem was to decide which earthquakes were to be studied in the frame of BEECD.
In principle it would have been recommendable to start investigating earthquakes with level III roots. However, as a comprehensive investigation of all the European earthquakes was out of the scopes and possibilities of BEECD, it was agreed to allow priority also to levels I and II, in order to get a consistent amount of data ready within the time and resource limits of the project.
Therefore, partners started investigating earthquakes, the parameters of which rely on low quality roots and, additionally, key-events for some areas, for which an improvement of the present knowledge was considered necessary.

a) Standard investigation
For Italy, Albania, Greece, Germany, Catalonia, UK, Slovenia, Hungary, Bulgaria, etc. a standard methodology was adopted for obtaining new, upgraded roots. It consists of few steps here described:

    1. state-of-the-art at the beginning of the investigation;
    2. basic investigation: retrieval and reappraisal of the information supplied by the bibliographical references/studies/sources quoted by the root for each earthquake in study. This goal was achieved by tracing back as many primary sources as possible, especially those quoted but not reported nor fully used by the previous root. Then a new root was obtained processing ex novo the whole set of information and assessing intensities;
    3. basic + ad hoc investigation: in case the previous two steps did not succeed in collecting information sufficient to upgrade the root, ad hoc investigation was carried out taking into account published or, in a few cases, unpublished sources describing earthquake effects.
Such investigation was reported according to a standard format (see See A scheme for reporting a standard investigation producing a new root), which evidences the previously described steps, contains the original descriptions of earthquake effects and presents today knowledge by means of a summary report, a table and a map of affected places.

b) Extensive research
For the earthquakes of the Balkan area, the knowledge of which is generally of low level, it seemed more convenient to start a general investigation: ICST, London, took care of it. The study area included former Yugoslavia, Bulgaria, Albania, Northern Greece (north of 39°N), Turkey (west of 27° E), Romania south of 44° N. The retrieval of local information has been carried out with temporary assistants in Sofia, Istanbul, Athens and, after May 1996, with a full time assistant in London.
All published and a number of unpublished catalogues available at ICST for the study area were collected, and events before 1850 have been traced back to original sources. Most of these sources, about 500, have been retrieved and read. The search in Ottoman archives in Istanbul confirmed that there is relatively little information to be found in these repositories, and retrieval work was discontinued late in 1996. Regarding Slavonic sources in Sofia, Thessaloniki and London, again here there is a dearth of information concerning earthquakes. For Northern Greece new sources from Athens, Thessaloniki are adding a considerable number of new and little-known events, chiefly for the 19th century, through press reports which are contributing additional information for the whole region.

Todate, the research permitted to collect information on a number of earthquakes of all sizes for the period before 1900 from original, contemporary and near-contemporary sources. Also, 40 damaging earthquakes, not recognised previously as such, have been identified and studied further. For about 400 of these earthquakes a report was prepared.
App. D7 contains a description of the methodology adopted and a sample of important earthquakes studied in the area.


Altogether, 618 new, BEECD roots have been produced.

Investigation of type a) was carried out for about 197 earthquakes, distributed as follows:

Examples are shown in App. E2.1 to E2.11 and E3.1 to E3.5.

Investigation of type b) was carried out for 419 earthquakes in the Balkan area (ICST, London).


Summarising, the studies performed in the frame of Task 3 did retrieve or produce about 1653 new roots (App. F1). They were given a root class and filed in BEECD format becoming the new roots file (NRf): the parameter Ds (data set source) was given codes assessing type, origin country and source of the root (App. F2).

They include 165 roots concerning so-called "fake quakes", that are, earthquakes inserted in the PEC on the basis of careless conclusions which were afterwards proved false on the basis of rigorous historical investigation. It seemed opportune that investigations concerning earthquakes which proves an earthquake to be fake are reported in a similar way as for the other events, with special reference to the explanation of the causes of the distortion which lead the fake event to be inserted in the catalogues (App. E3.1 to E.5).
To avoid that events proven as fake are simply cancelled from files without leaving trace (and to avoid future re-apparition because someone might considered them as forgotten), the corresponding roots were filed in the same way as for true earthquakes (App. F2) and given a code beginning with Z (zombie entries) to the parameter Set (source entry type).

Finally, for the earthquakes for which no new better roots were retrieved or produced, the root supporting the corresponding F entry in the WF was retrieved.


A scheme for reporting a standard investigation producing a new root

Scope. New roots, either of the best type (type 1, studies with intensity datapoints) or of type 2,
are worth to be supported by a report where the author summarises:

Though parameters determination is not a part of this step, suggestions in view of it can be helpful.
Here follows the main points to be considered for a standard report. They represent a minimum set
of information, which can obviously be expanded.

0. Title. It contains the date and identification of the area of maximum effects of the event, as resulting from the investigation.

1. State-of-the-art before the investigation. This section should give:

2. Basic investigation. This section should give: This section might also contain information about the solution of timing and locality identification problems.

At this stage a new root can be obtained by interpreting the most relevant records; the root class
can be evaluated. If the investigation will stop here, section 4 and next can be prepared.
If the root level will score below the agreed threshold, further investigation will be necessary.
In this case the report will include also section 3.

3. Basic + ad hoc investigation. This section will be dedicated to report the main steps of the investigation and its results. Two main types of investigation could be taken into account:

The results will be reported according to the same scheme as before.

4. Intensity assessment and datapoints. This section should give:

5. Suggestions for earthquake parameters determination. This report is intended for describing the root; the parameter determination should be another step of the process, preferably not performed earthquake by earthquake. However, in this section the investigator may summarize from his knowledge of data some warnings useful for this purposes.

6. References.