The second generation of seismological instrumentation

From 1964 to early 1990-ties: band-limited electromagnetic seismometers

with galvanometric registration on photo paper

 

The continuity of the instrumental monitoring enabled soon after the strong Skopje earthquake of 26 July 1963 gave the data-base for further seismological and seismotectonic investigations of the Skopje epicentral area.

           

2 Rubrika Za OPSER Sl Br  Seizmometar horizontalna komp

joint project of the Institute for Physics of Solid Earth,Moscow

(Up) A short-period electromagnetic seismometer type VEGIK constructed to reflect the ground motions in a horizontal direction. (Down) One of the stations installed in Skopje area during the joint project of the Institute for Physics of Solid Earth “O. Yu. Shmidt” from Moscow and the Seismological Station in Skopje. The station is consisted of three short‑period electromagnetic seismometers type VEGIK, set in a way to reflect the ground motions along the vertical direction and the directions North–South and East–West.

 

A project for such investigations was prepared by the Seismological Station in Skopje in 1963, in cooperation with many Yugoslav seismological and geological institutions and UNESCO experts (Nicholas N. Ambraseys and others). The Seismological Station in Skopje and the Institute for Physics of Solid Earth “O. Yu. Shmidt” from the Academy of Sciences of USSR in Moscow (Russian abbr. IFZ) were chosen to perform the project. The members of the joint team were: D. N. Rustanovič (a supervisor, from IFZ), E. A. Koridalin (a consultant, from IFZ), S. V. Medvedev (a consultant, from IFZ), V. A. Tokmakov (a consultant, from IFZ) and D. Hadžievski (a consultant, from the Seismological Station in Skopje). Ten modern seismological stations, consisted of short‑period electromagnetic seismometers type VEGIK, GSH, VSH and VBP-3 with galvanometric analog registration on photo paper (all made in USSR), were provided by IFZ. Funding for the work of the team was provided by the Directorate for Reconstruction of Skopje, via the Geological Survey of Macedonia (Skopje).

The joint team started its regular work on 12 April 1964. The ten local seismological stations were installed in the seat building of the Seismological Station in Skopje, at five sites in the town of Skopje and in the surrounding villages of Matka, Brazda, Lipkovo and Katlanovo. Periodically, some other experts from the Yugoslav seismological and geophysical institutions took part in the working of the team. These were Josip Mokrović, Dragutin Skoko and Dragutin Cvijanović (from the Geophysical Institute at the Faculty of Natural Sciences and Mathematics in Zagreb, Croatia), Vladimir Ribarić (from the Geophysical Institute of the University in Ljubljana, Slovenia), Miloš Janković (from the Seismological Survey of Bosnia and Herzegovina), Slavko Vucinić and Nikola Jovicević (from the Seismological Survey of Monte Negro). Other participants were 40 laboratory technicians. These were the students Andjelka Milošević, Beatriče Force and Ivo Vukšić from the Geophysical Institute at the Faculty of Natural Sciences and Mathematics in Zagreb, and, further, students from the Department of Physics at the Faculty of Natural Sciences and Mathematics in Skopje, as well as from other faculties in Skopje. Two of the students from the Department of Physics at the Faculty of Natural Sciences and Mathematics in Skopje, Simeon Ordev and Nikola Vasilevski, showed a special interest in seismology, which was the reason for their permanent employment at the Seismological Station in Skopje.

   Nicholas N. Ambraseys (http://cires.colorado.edu/~bilham/Ambraseys.html и http://cires.colorado.edu/~bilham/NicksPubs/Ambraseys%20photosSkopje.html), then an expert of UNESCO in engineering seismology, and, later a world-known scientist in this field, visited the Seismological Station in Skopje during the work of the joint team, namely in 1964. (Ambraseys used to keep his contacts with the Seismological Station in Skopje until his death, in 2012. His last visit to the station was in February 1999, when he cameto Skopjeforraising the Skopje City prize13 November” (in the category ofinternationalcooperation)for 1998. He got this prize forhisrolein therebuildingof Skopje after the devastatingearthquakefrom 26 July 1963.)

In that way, the Seismological Station in Skopje became a centre in which most advanced methods of seismological observation, scientific interpretation and practical implementation of seismological data were employed. At the same time, the station was a school for new seismologists.

The joint project of the Institute for Physics of Solid Earth “O. Yu. Shmidt” from Moscow and the Seismological Station in Skopje yielded important results on the main parameters and source of the 26 July 1963 Skopje earthquake, the seismicity and the seismotectonics of the Skopje area. The Seismic Microzoning Map of the City of Skopje made during the project was further used as a basis for elaboration of the urban plan of the city. Many of these results were included in the periodical publications of the station, which started to be issued from 1965.

The work of the USSR seismologists was completed on 21 April 1965. The Seismological Station in Skopje bought the ten new-installed stations with financial support from the Directorate for Reconstruction of Skopje, and independently resumed the activities related to these stations.

 

      Sketch of the building of the Seismological station in Valandovo

The station was put into operation on 16 February 1966

Sketch of the building of the Seismological station in Valandovo (designer – the graduated architect Janko Konstantinov, Skopje, 1965), and a photo of a part of the building taken in July 2013. The station was put into operation on 16 February 1966.

 

2 Rubrika Za OPSER Sl Br  Ohrid stanica zgrada za instrumenti

2 Rubrika Za OPSER Sl Br  Ohrid stanica kuca

The buildings of the Seismological station in Ohrid. The location is in the area Varoš, near the church of St. Caneo. The station was put into operation on 9 September 1967.

 

            In December 1964, the station in Skopje started an upgrading of the seismological service by procurement of additional equipment. One part of the new equipment (beside the set of three short‑period electromagnetic seismometers type WILLMORE, the STRONG-MOTION RECORDER AR-240 and other sensors), were the set of three short‑period electromagnetic seismometers type LEHNER-GRIFFITH and the set of three long-period electromagnetic seismometers type PRESS-EWING. (Installed with galvanometric analog registration on photo paper, they will operate up to the early 1990-ties.) At the same time, the reconstruction of the building of the station in Skopje and the construction of two new seismological stations in Valandovo and Ohrid started. Two sets of three LEHNER-GRIFFITH seismometers with galvanometric analog registration on photo paper were provided for the stations in Ohrid and Valandovo. The UN Special Fund provided the necessary resources for all these actions.

In addition to the engagement of the whole staff of the Seismological Station in Skopje, valuable scientific and professional assistance was also provided by D. Skoko from the Geophysical Institute at the Faculty of Natural Sciences and Mathematics in Zagreb, N. V. Shebalin from IFZ in Moscow (then expert of UNESCO in Skopje) and M. McElheny from the United Electrodynamics (Earth Science Division, Inc.), Pasadena, California, USA. The later company was the supplier of the entire new seismological equipment.

            The new equipment of the Seismological Station in Skopje was put into operation on 14 March 1966. The seismological station in Valandovo (VAY) began working on 16 February 1966, whereas that in Ohrid (OHR) started on 9 September 1967.

 

      2 Rubrika Za OPSER Sl Br  LEHNER-GRIFFITH Vertikalna 2 Rubrika Za OPSER Sl Br  PRESS-EWING vertikalna komp

The vertical components of the short‑period electromagnetic seismometer LEHNER-GRIFFITH and long‑period electromagnetic seismometer PRESS-EWING in the seat building of the Seismological Observatory in Skopje. (The both seismometers are made in USA.)

 

2 Rubrika Za OPSER Sl Br  Seizmoloska Zdraga Skopje akvarel 1966

An aquarelle of the seat building of the Seismological Observatory in Skopje from 1966

 

The intensified activities of the Seismological Station in Skopje imposed its reorganization. In 1966, it became a Seismological Observatory within the University of Skopje.

 

2 Rubrika Za OPSER Sl Br SKD EW 2 DSC09547

One of the middle-period elecromagnetic seismometers SKD (USSR production) purchased by the Seismological Observatory in Skopje in 1974. The shown seismometer is installed in the seat building of the Seismological Observatory in Skopje in a way to reflect the ground motions along the direction East–West (SKD E–W component).

 

2 Rubrika Za OPSER Sl Br  VIDEO REKORDER VR-1 ZLOLEMEN

One of the analog recorders type VR‑1 (Kinemetrics Inc., USA) purchased by the Seismological Observatory in Skopje in the middle 1970-ties.

 

            During the 1960-ties and 1970-ties, the Seismological Observatory in Skopje performed instrumental observations and investigations of seismicity also of epicentral areas beyond Republic of Macedonia: Leskovac area (Serbia) in the period 1 June 1967 till 15 December 1968, by three own seismological stations; Banja Luka area (Bosnia and Herzegovina), after the strong earthquake occurred there on 27 October 1969 (in fact, from 29 October 1969 till 31 May 1971), with five seismological stations, jointly with the Institute of Earthquake Engineering and Engineering Seismology (IZIIS) from Skopje; in the Montenegrin coastal area, after the strong earthquake occurred there on 15 April 1979 (in fact, from 10 May 1979 till 10 October 1979), by two seismological stations.

In the period 1970–1976, the Seismological Observatory in Skopje participated in the international UNDP/UNESCO scientific-research project on investigation of the seismicity of the Balkans. The main office of the project was in Skopje. The cooperation with world-known seismologists and experts of UNESCO (V. Karnik, T. S. Algermissen, N. V. Shebalin, A. R. Ritsema, V. V. Belousov, C. R. Allen, L. Christoskov, J. Drakopoulos, C. Radu and others) within this project led to a considerable progress of the оbservatory. The Editor-in-Chief of the project, the world-known seismologist Vit Karnik (one of the authors of the famous MSK-64 macroseismic scale), stayed in Skopje the longest time, with accommodation in the building of the observatory. (In that time, Vit Karnik was employed in the Geophysical Institute of the Czechoslovak Academy of Sciences, Prague). During this project, in 1974, the Observatory installed a set of three middle-period electromagnetic seismograph SKD with galvanometric analog registration on photo paper (made in USSR), as well as an electromagnetic accelerograph type OSB-I MP with galvanometric analog registration on photo paper (an USSR make). At the same time, the observatory also procured three analog recorders type VR-1, which use a needle with ink over white paper put on a rotating drum (a product of Kinemetrics Inc., Pasadena, California).

 

the band-limited electromagnetic seismometers LEHNER GRIFFITH (short period)

PRESS EWING (long period) and SKD (middle period)

The seismological station at the seatbuilding of the Seismological Observatory in Skopje: (up) the band-limited electromagnetic seismometers LEHNERGRIFFITH(short‑period), PRESS‑EWING (long‑period) and SKD (middle‑period), used from the middle 1960-ties up to the early 1990-ties with galvanometric analog registration on photo paper (down).

 

In the period 1970 to 1974, the Seismological Observatory in Skopje elaborated the scientific-research project Seismic Zoning of the Territory of SR Macedonia, together with the Institute of Earthquake Engineering and Engineering Seismology and the Department of Geotechnicsat the Faculty for Civil Engineering. For the needs of this project, six temporary seismological stations (equipped with sets of short‑period electromagnetic seismometers type VEGIK with galvanometric analog registration on photo paper) were installed in the towns of Veles and Star Dojran, and at the dams of Kežovica (near the town of Štip), Došnica (near the town of Demir Kapija), Turija (near the town of Strumica) and Tikveš (near the town of Kavadarci). A very important result from this project is the Seismic Zoning Map of Macedonia.

             The above two projects clearly pointed out the need for installation of a denser network of permanent seismological stations in the territory of Republic of Macedonia. Since then, a number of programmes referring to this problem have been developed at the Seismological Observatory in Skopje.

On 11 May 1976, the Seismological Observatory in Skopje became a member of the Skopje University Centre for Mathematical and Technical Sciences. On 14 June 1976, the Seismological Observatory in Skopje joined the Faculty of Physics in Skopje, the later being also a member of the mentioned centre. On 12 December 1984, the Faculty of Natural Sciences and Mathematics in Skopje was again established, and the observatory became one of its institutes.