3-D Monitoring of Active Tectonic Structure

Ziel

Objectives

The main objective of the action is to study detailed data about micro-displacements of the ground on selected tectonic fault planes of tectonically active regions, producing either seismic or aseismic movements, and their monitoring, interpretation, evaluation and exploitation in various fields of science, research, development and society.

This objective is to be reached by establishing following steps:

(a)Establishing of local monitoring points and their networking on selected tectonic fault planes of tectonically active regions.

(b)Collecting of data on detailed movements in monitoring point 3-D micro-displacements.

(c)Interpretation of the data in terms of mechanical behaviour of the investigated tectonic structures.

(d)Detecting of long-term trends, as well as other characteristics of the movements.

(e)Finding of correlation with other scientific findings and known results of regional measurements.

(f)Evaluation of results of the above mentioned steps, dissemination of results and their exploitation.

Benefits

Scientific relevance

(I)In seismically active regions quantitative data about micro-displacements on tectonic fault planes can be correlated with seismic events of specific areas in order to improve knowledge about active mechanical processes and to find earthquake precursors. The data can be used therefore in seismic hazard assessment of specific areas.

(II)In seismically less active regions quantitative data about micro-displacements on tectonic fault planes can produce information about slow creep tectonic processes leading to macro-displacements possibly on a geological time scale. Thus, morphological phenomena can be explained and the processes verified. In other cases stability can be checked.

(III)There is a chance to make comparative studies of individual regions. Mediterranean territories are seismically highly active, and can thus benefit directly from seismic studies. On the other hand, territories like those of Central Europe which are of lower seismicity may benefit from comparing data with areas where processes are more clearly pronounced.

(IV)Monitoring in international cooperation will provide a benefit from the implementation of progressive technologies and experience, since it calls for a high resolution and stable instrumentation. Application of moir crack gauge instrumentation (Czech Patents No 131631 and 246454) tested under field conditions, and successfully used in several long-term field measurement projects forms an integral part of the Action.

(V)Quantitative detailed 3-D in-situ data about micro-displacements are generally not available for geologists, and leave doubts about actual function of individual faults in investigated regions. Systematic checking of all the three deformation components always at one point simultaneously is to avoid misleading information based on separate horizontal or vertical measurements. New special progressive methods of monitoring allow for a proper interpretation of investigated geological processes. Proper data interpretation is especially necessary to discern reactions of the Earth Crust origin from other superficial deformations, mostly gravitational that can simulate deep tectonic reactions.

(VI)Direct in-situ 3-D measurement allows for detecting long-time slip movements along structural discontinuities in spatial orientation. Data about slip movements, notably vertical and horizontal, are of the highest interpretative value, because they often allow differentiating between gravitational and other effects. Thus, they can indicate areas of positive tectonic movements contrary to frequent slope movements. Being clearly identified, tectonic movements can be investigated later by other more complex regional projects. The measurement is going to be used as a comparative method for other modern position monitoring techniques (such as GPS) providing an opportunity to validate their findings and reduce their error interval.

Relevance in society

This relevance can be recognised in connection with seismological research concerned with hazard in populated areas, as well as in connection with stability conditions in the context of the storage of radioactive waste, long-time rock stability along tracks for high speed trains and pipe lines that are constructed, deep road and railroad tunnels, and other underground structures like penstock and water supply inlet structures in tectonically active mountains, as well as preservation problems of historical monuments of mankind. In all similar situations active movements are to be detected quantitatively by monitoring prior to construction for adequate preventive security measures to be taken. In most such cases particular fault structures have to be investigated in detail, or even permanently monitored during their lifetime, and there is no doubt that strict regulations to take such investigations will be legislated for ever more frequently on security reasons.

C.SCIENTIFIC PROGRAMMME

The programme is directed to active tectonic movement investigation. Direct field measurements on tectonic structures allow for evaluation of the stability or the mobility degree of the investigated zones and for finding characteristics of the mechanical processes involved.

State of the art

(a)Monitoring

All known facts about the Earth Crust processes call for movement monitoring and many projects have been started. On scale they range in a spectrum from global to regional and local studies, and integrate seismic networks with GPS and precise surveying

Several segments defined by typical monitoring precision and error intervals can be noted. Present GPS programmes are directed mainly towards surveying larger, even continental regions, and represent a segment of highest scale. They provide valuable data interpreted as strains in extensive fields (e.g. in the Mediterranean and Turkey recently). Yet, activity of individual faults has to be derived on theoretical basis, since data of this kind are not related to detailed structures.

Therefore, local networks are to be set to obtain data in more detail on a segment of a lower order. The data are, however, often distorted by local superficial processes, not easily discernible from space, if performed by GPS, and combined with usual surveying methods performed at long time intervals. Moreover, the resolution capacity of such observations appears at the edge of their standard error.

There are resolution limits, which GPS and other surveying methods can scarcely improve upon. Even precise levelling, a rather professional and arduous surveying method applicable in most detailed local projects, cannot provide data better than close to one mm. The same is applicable for electro-optical range finders (Kern Mekometer). The practical limit of sensitivity for GPS is a matter of discussion among professionals. In any case, it is not higher than close to one mm in horizontal, and considerably lower in vertical. Besides, such measurements cannot be repeated frequently, leaving relatively long periods uncovered. There are also financial limitations of such projects, which limit setting of permanent GPS stations, as well as of other more sophisticated techniques. Moreover, electronic extensometric instrumentation can be rarely considered stable over prolonged periods of permanent use. As a result, quantitative data about present local fault movements are quite scarce. There is a need for detailed in-situ long-term high precision monitoring on individual faults, which would fill the gap, and provide an opportunity to organise a monitoring segment of even higher resolution than space and survey techniques have provided.

(b)Geomorphologic studies

Geology and geomorphology observe and describe fault zones and even individual faults. These are observed in nature as structural planes that clearly separate individual blocks of rock and zones of movement showing serious relative displacements that are easily apparent as steps and other geomorphologic phenomena. The movements are obvious, and often closely connected with other morphological details, and phenomena. However, regarding the geological time scale the movement is often so slow that the actual mobility of the fault and present movements on it can be questionable. The process leading to such a fault formation may have been of a different character such as continuous of a creep character or discontinuous of an incremental character. These are implications that leave quite a deal of uncertainty in the interpretation of many natural phenomena. The interpretation is often based on movement assumptions that need to be checked, and only detailed data on moving faults may provide real boundary conditions of the structural blocks.

The lack of such checking with verification of the boundary conditions is the main need calling for the suggested COST action. There is a need to get over the barrier of sensitivity in monitoring methods due to slowness of the movements on a geological time scale, to get data so detailed as to discern directly mechanical aspects of natural movements on structures, while overcoming field problems in monitoring.

Programme

1.Interdisciplinary approach

Fields in geology, morphology, seismology, and tectonics have to be discussed in terms of physics and rock mechanics, as well as those of monitoring techniques. There is a need for specialists to meet in interdisciplinary groups, where professional geological knowledge would meet with technical skill and practical experience. Contrary to global studies, where large geodynamical concepts are studied often in laboratories in limited contact with field, detailed structural studies call for even more fieldwork, with a good familiar contact with detailed situation at the place. Therefore, professionals working systematically in the investigated regions must be involved. Their cooperation in the selection of representative measurement points is an absolute must. Such professionals have, in their particular region, their long-term, not to say life-long projects, which are to be promoted with the project. Therefore, ongoing projects of individual groups are expected to be continued and integrated, yet innovated by technical means and practice of the cooperating specialists. It is strongly felt that this is more important, than to create a new, more innovative field study. As a matter of fact, to move to more detail had always an innovative effect.

2.Partnership

As for partnership, there is a common fact, that partners from seismically more active regions, like the Mediterranean, urgently need more detailed data, calling for help in their field studies. They may have investigated the movement with paleogeographic, paleoseismic, and other relevant methods, having neither direct verification of it, nor quantitative data. On the other hand, partners from less active regions (Central Europe) have had to develop sensitive methods to detect even low order processes occurring in their countries, although interpretation they need calls for analogy from more active regions, where processes proceed faster, with more obvious results. Thus, the needs of cooperating groups may be met. The following are the intended areas where investigation of selected fault structures has been preliminarily assumed: Granada Basin (Spain), Central Apennines (Italy), G¢ry Stolowe - Jaskinia Niedzwiedzia (Polish - Czech boundary region), Krupnik epicentral area (Bulgaria), Rhine Fault near Karlsruhe - Ettlingen (Germany).

3.Seismic and aseismic processes

The processes under study can produce a wide range of movements in displacement limits related to intensity and period in which the process occurs. The processes are to be of different character, yet representative for Earth Crust stresses and rock mass properties. Most generally, the processes are supposed to reflect some of the deformation models of rheology combined with structural transformations. All theories about it need quantitative data for evaluation and verification. There is a well-known fact that theoretical models and field observations do not coincide too often and the modern approach is now ever more often based on back analysis employing field monitoring data rather than laboratory ones.

The most dangerous and damaging are earthquake movements when the stored energy of deformation is released. An earthquake is a resulting, often periodically repeated phenomenon of instability in the deformational process of a tectonic character. It occurs when the state of stress in the Earth Crust and local internal conditions of the structure become unstable. Such a state produces not only vibrations but even irreversible displacements, which mark the origination of a new stage under conditions of newly found local balance in the process which is going to continue without excessive deformational increments. Such a description represents a process, which is highly variable in observable manifestations. These, most of the time are at low levels for discernment. This fact calls for a systematic long-term monitoring with a highly stable instrumentation of high power of resolution.

4.Increased resolution techniques

The programme cannot be successful unless an increased resolution in the monitoring system can be reached. With that aim in view all accessible methods of surveying can be employed, if they prove suitable for long-term measurement. Methods that can produce direct displacement data better than that of one mm order should be preferred or applied to reduce errors in higher order survey segments. A multisegment monitoring system developed and described in general principles by Cacon & Kontny (1993), can be well used in a way analogous to the geodynamical polygon that has been implemented successfully in Sudeten. The method integrates different survey methods in four segments. Three segments concern the geometric registration of displacements in three dimensions, the fourth covers dynamic gravity changes. Measurement methods used are to be chosen to correspond with the range of observation and required registration accuracy in individual regions to cover individual research areas with appropriate quality of network. Thus, precise surveying segment of local geodetic or GPS network coupled with a local extensometric system, which represent a segment of smallest-scale end, may reduce mean error of the higher segment, which, on the other hand, will couple detailed relative measurements with a larger area investigations.

Recent monitoring experience of engineering geology, gathered during long-term (i.e. years to decade) site investigations should be consulted. Regarding that, repeated precise levelling and precise tape measurement in profiles, long distance electro-optical rangefinder measurement, detailed crack gauging based on mechanical-optical interference are preferable techniques, while inclinometers (either contact, borehole, or geophysical) cannot be recommended. New seismic instrumentation is not assumed as seismic data are well documented regionally.

5.Applications

(a) Science

The scientific programme of the Action is directed primarily to collecting data about more detailed development of micro-deformations on several comparable tectonic structures well described regionally. The data are supposed to be combined and confronted with other scientific facts, if necessary, including results of other sources of movement investigation. The data about individual tectonic structure behaviour are believed to be a source of basic information interpretable in many scientific branches. A direct application is felt in the domain of earthquake mechanism, its preparatory stage and precursory reactions. Other applications can be indicated in all scientific branches that deal with Earth Crust and rock mass deformation.

(b) Society

Relevance of this kind of research for society and the general scientific horizon, going far beyond pure scientific interest can be well recognised.

It is the relevance in connection with seismological research concerned with hazard in populated areas and environment. The example can be given in microdisplacement monitoring of selected tectonic structures in Peter the First Range of Pamir Mts. in Tadjikistan, carried out by Russian Academy of Sciences at Garm Geodynamic Test Site - Kost k, Nikonov et al. (1992), Stemberk, Vil¡mek, (1992). The test site was established after the catastrophic series of Chait earthquakes of June 1949, which released a volume of about 0,5 billion of m3 of rock, and caused land devastation and almost total depopulation of the large area for several decades after the earthquake.

There is no alternative for measurements of this kind in investigations of stability conditions of technical installations and objects with potential heavy impacts to population and environment. Due to Earth population growth, ever larger and more hazardous areas are encompassed by civilised life. Let us name modern technical problems: storage problems of radioactive waste, long-range rock stability along tracks for high speed trains that are constructed, pipe-line networks, and other underground structures like penstock and water supply inlet structures in tectonically active mountains or deep road and railroad tunnels. (See example of monitoring in a railroad tunnel cutting through one of the parallel fault lines of Rhine Fault in Germany - Fecker et al. (1999)).

Another important application can be found in the preservation of historical objects. There is an increased concern that historical monuments of mankind are threatened by devastation due to insufficient care in the past. Especially repeated seismic events may result in a progressive deterioration. In that, there is a necessity to know seismic risks due to movements quantitatively. (See example of the joint monitoring on a rock face bearing a first class historical bas-relief monument under reconstruction in a seismic region of Bulgaria. The monument "Madara Horseman" has been listed among objects preserved by UNESCO - Kost k, B., Dobrev, N., Zika, P., Ivanov, P. (1998)).

In all similar situations active movements with their impacts in the environment should be detected quantitatively prior to any construction or preventive adequate security measures to be done in the area. In most such cases particular fault structures have to be monitored in detail, or even permanently.

There should be no doubt that strict regulations will be legislated ever more frequently to take such investigations for security reasons. Results of the Action may be used in drafting European civil engineering standards in monitoring of tectonic structures interfering the construction sites and foundations.

D.ORGANISATION AND TIMETABLE

Organisation principals

This action brings together local specialists in regional tectonics, geomorphology, and seismology, with partners well experienced in monitoring of micro-deformations. Specialists from such different fields must decide about suitable and representative regions, well investigated structures, accessible and representative points for monitoring in the field and about technical conditions. The decision must take all regional and local aspects into account, as well as monitoring techniques. Monitoring design must be realised with respect of local conditions.

When a research organisation decides to join the programme it is expected to take an initiative in suggesting studies of a regional tectonic structure, which has been thoroughly investigated in the region. Generally, it is supposed that the group is currently engaged in such a research programme. The selection will be revised by other partners regarding its scientific importance and evaluated technically by specialists as to facilities and steps to be done. Individual research programmes are expected of different orientations with different accents stimulating other partners, nevertheless with a general universal need of rock movement detection. Local monitoring networks are to be organised on a standard instrumentation system as far as possible, adopted to local conditions, and on the basis of full local responsibility financed from a local budget as a COST action. All necessary decisions are to be made to organise a local in-situ monitoring programme with centrally organised technical support of specialists. This support will include instructions as to instrumentation under local conditions and technical maintenance. The local group will then take care of the local monitoring points as to general maintenance and prevention of instrumentation damage.

The technique has to be partially financed locally (permanent instrumentation), which is the responsibility of the individual groups and their regional or national authorities, and partially shared (movable systems and data centres). Basically, individual groups will work with individual budgets covering all activities related to their own territory. To cover common actions, there is to be a clear consensus of financial responsibility beforehand.

Monitoring data will be at the disposal of individual groups, yet evaluated centrally. They are to be accessible to all partners, and discussed jointly. A period of three years of local data acquisition is expected to be an introductory period, after which a more serious interpretation can start. Workshops will be organised for practical discussion and field excursions, later to solve problems of data interpretation and application.

The programme as a joint long-term observation project, needs certain joint steps, as well as local organisational ones. Local steps are those particularly connected with establishing local monitoring networks. Such local programmes will be individually designed, differing in size according to local conditions. However, a basic 3-D monitoring instrumentation technique is supposed to be standardised, and data proceeded in a uniform manner to obtain comparable data. The technique may be regionally supplemented with other monitoring methods.

Timetable can be represented in a series of following periods:

1.Design period.

Designs of in-situ monitoring programmes for individual countries where important monitoring regions and points will be selected for investigation.

One year

This step represents the initial period of the cooperation. Each partner is to become acquainted with the programme and its facilities, make visits to see working field monitoring facilities, reconsider its priorities well as to the objectives in the regional field investigation and use of the field data that are to be acquired. The preferential goals will not be necessarily exactly the same in individual countries regarding the many local regional and structural dissimilarities, and even different research programmes under way, where data about tectonic movements are applicable.

Monitoring specialists will be acquainted with local field situation and prepare technical design.

2.Instrumentation period.

Monitoring network will be instrumented. Regional service will be organised.

Three months for each regional project

After obtaining agreement between partners about individual goals, suitability and potentials of the technique, and mutual availability of the data, the monitoring is to be organised, i.e. individual observation points in different regions are to be selected and equipped in mutual cooperation.

The main coordinator will technically support setting up of the 3-D instrumentation. Supervision of individual observation points will be organised with local support.

Simultaneously, facilities of individual partners will be combined, other methods like geodetic, if possible, implemented, and communications organised.

The Institute of Rock Structure and Mechanics, Ac. Sci. Czech Rep., Prague is ready to set up a data centre on the basis of existing facilities for 3-D point extensometric data.

Similarly, data centre for acquired data of geodetic and GPS measurements will be set up in the Agricultural Faculty, Laboratory for Geodesy and Photogrammetry, Wroclaw, Poland.

3.Data collecting period.

Data will be collected regularly, sent to the data centre, and centrally registered and checked.

Instrumentation will be checked and kept in operation.

Initial period of three years for each regional project

Data collection of 3-D micro-displacements will be organised with local attendance, which needs one local person for occasional observation point visits. Local attendance instructions will be set up. Experience shows that manual registration of data at individual points by local attendance is simple, appropriate, and does not call for qualified personnel. Local attendance will collect data regularly in accordance with the instructions, at a frequency appropriate to local situation, i.e. once a month approximately, and report immediately extraordinary events, like earthquakes, or even make an immediate visit to the observation points after the event.

At about three-month periods regional data are to be collected and sent to the centre for processing. Centre will report and comment on data once a year. Extraordinary results are to be discussed immediately.

If necessary, technical support for maintenance of the instrumentation will be organised from the Action chairmanship centrally.

Meanwhile, data obtained with the use of other methods will be stored and processed at intervals appropriate to such methods.

Contacts and comments stimulating further research are to be invited and circulated.

4.Interpretation period

Data centre general report, including general interpretation. Regional reports. Joint interpretation discussion. Workshop.

Six months after finishing three years of the initial period of monitoring.

The workshop will be designed to compare results from individual regions, to interpret them properly, to present results in related fields of research, and to make decisions for further cooperation and continuation of the research.

Special attention is to be paid to all the questions of the scientific programme.

5.Established monitoring period

Second observation period in a length of two years.

A three-year initial period is at the minimum. It is needed to obtain significant data from points organised under field conditions with climatic effects. There is a general experience that significance of data increases seriously with length of the observation period, notably for a long-term observation, which is the case. This second period of two years is expected to provide highly significant data.

This is a period when regional teams can apply the data and derived facts in their research activities and theoretical deductions. Meanwhile, observations in regional network will continue.

During this established monitoring period field registration work and data collecting of 3-D micro-displacements is expected to become routine work, with little maintenance of the instrumentation. New points will be found and evaluated as potentially representative for observation, and local networks completed, if necessary.

Future actions will be discussed. Prolongation of the joint research is evidently expected with possible modification and actualisation of the programme on a basis found most suitable to individual partners.

E.ECONOMIC DIMENSION

Expenditure of individual partners of the action will vary in respect of the size of accepted monitoring programme (network size and additional measurements). They can be approximated and calculated using figures given in the following. However, individual partners will prepare their own budget with detailed specification of expenditure.

Individual expenditure can be estimated regarding:

(a)regional costs covering instrumentation and maintenance of a 3-D micro-displacement regional network and data collection,

(b)costs to carry out additional measurements,

(c)local research to correlative data, and field documentation,

(d)data centre costs,

(e)international meetings and travel,

(f)coordination costs,

(g)overhead.

Guideline figures of expenditure for one partner and 3 year initial period in EURO:

(a)3-D instrumented monitoring network of 20 points30 000
Registration/organisation/maintenance network in 3 year operation,
approx. 5000 per year at monthly registration frequency15 000
operational assistance to field measurements by specialists11 000

(b)additional monitoring programme (e.g. GPS)
stabilisation of 20 GPS points24 000
4 measurement rounds16 000
specialist assistance to organise measurements 8 000
rent of instrumentation 8 000

(c)local research to correlative data, and field documentation,
joint work with partners (expenditure related to the size of the
established networks),
2 network standard 3-D network research 30 000
an additional research programme30 000

(d)international meetings, workshops, field travel,
3 international visits yearly15 000

(e)data centre costs,
3-D data centre 1 000 yearly per partner 3 000
GPS data centre 1 000 yearly per partner 3 000

(f)coordination costs 1 000 yearly per partner 3 000

(g)15% overhead applicable
to a/ 8 400
to b/ 8 400
to c/ 9 000
to e/ 900

Total a/ to g/ first 3 year period per one partner 222 700

The second two year period of established monitoring will intensify research work and bring about improvements in the monitoring systems. Meetings of all the partners will be necessary for joint discussions. Thus, expenditure of the COST Action in the second two year period will be approximate to the first period.

Using previous data the financial dimension of the COST Action can be calculated.

Financial dimension of the COST Action for 7 partners and two periods, of a total of 5 years duration comes to:EUR 3 117 800

F.HISTORY OF THE PROPOSAL

The Action preceded a meeting of several experts from Czech Republic, Poland and Spain held in Prague, September 1996, and followed by excursions to IRSM (Institute of Rock Structure and Mechanics, Academy of Sciences, Czech Republic) field monitoring facilities in Krusn Hory Mts., and Ostas National Reserve in NE Bohemia, as well as to similar facilities on the nearby Polish territory (Szceliniec Wielki Massif, Jaskinia Niedzwiedzia - Bear Cave, Kletno and Paczk¢w, GPS observation points near Zloty Stok) organised by Academia Rolnicza, Wroclaw, Poland. A final meeting was held in Boleslaw¢w with a decision to make steps for a closer cooperation in active movements monitoring on a wider international basis.

In June 1997 a Czech expert visited C.N.R. - Centro di Studio di Geologia dell'Apennino e delle Catene Perimediterranee, in Florence, Italy, to study field monitoring conditions in Central Apennines. The visit confirmed suitability of the action in the region.

Earlier, contacts were established between Czech, Polish, and Slovak experts resulting in monitoring cooperation regarding stability conditions of different objects. Recently, a limited monitoring programme was also arranged in Germany. A long-term cooperation between Czech and Bulgarian experts covering a period of 17 years of monitoring in an epicentral area of large earthquakes in SW Bulgaria resulted in successful acquisition of data about movements along local fault structures, and verified suitability of the suggested instrumentation.

The Action intends to employ instrumentation patented and tested successfully in a long-year scientific programme of IRSM, Prague (Czechoslovak Patents No 131631 and 246454). The Czech programme stimulated by the intended Action resulted in a monitoring project granted in years 1993-1995 by Czech Government Grant Agency financial support, Grant No 205/93/2342, finished and approved by the Agency document of July 22, 1996. A list of related publications is enclosed.

The availability of the instrumentation, field monitoring experience, and good results from earlier cooperation betwe

Programm/Programme

IC-COST - European cooperation in the field of scientific and technical research (COST), 1971-

Thema/Themen

3 - Environment

Aufforderung zur Vorschlagseinreichung

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EU-Beitrag

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Tschechien

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