Horizontal mechanical seismographs

 

 

Constructor – Emil Wiechert

 

Manufacturer:                                        Spindler & Hoyer

Year of production:                                                     1907

Seismometer natural period:                                     4–10 s

Damping ratio:                                                     (3–10):1

Pendulum mass:                                                        80 kg Static magnification:                                        14–30  times

 

The seismograph arrived in Zagreb on January 16, 1908 and was installed on January 28. The constants were first determined on February 1, when the seismograph started regular operation.

 

The seismograph operated at Grič until March 20, 1984.

 

 

Konstruktor – Emil Wiechert

 

Manufacturer:                                   G. Bartels, Göttingen

Year of production:                                                     1909

Seismometer natural period:                                      8–10 s

Damping ratio:                                                       (3–7):1

Pendulum mass:                                                     1000 kg Static magnification:                                         0–240  times

 

The seismograph arrived in Zagreb on March 12, 1909. Mohorovičić installed the seismograph in the basement of the building at No. 3 Grič, and set it in trial operation on March 16, 1909.

 

The seismograph was operating at Grič until March 27, 1984.

Due to the orientation of the room in which the seismographs were installed, horizontal axes were directed NW–SE and NE–SW, not as standard N–S and E–W. This setup is kept here as well.

Wiechert horizontal mechanical seismographs are still in operation - 24 hours 'live seismograms' can be seen on line.

 

 

Vertical mechanical seismograph

 

 

Konstruktor – Emil Wiechert

 

Manufacturer:                                         Spindler & Hoyer

Year of production:                                                     1929

Seismometer natural period:                                  4.4–5.0 s

Damping ratio:                                                       (5–8):1

Pendulum mass:                                                     1200 kg Static magnification:                                       190–240 times

 

The seismograph arrived in Zagreb in 1932. After a trial period it was calibrated and set in operation on September 28.

     The seismograph was operating at Grič until March 6, 1984.

 

Seismographs (disassembled into parts) were moved into this building on September 12, 1985. Professor Franjo Margetić and Radivoj Capar thoroughly reconstructed all parts of the seismographs (1985-1988). They spent 2775 hours in 907 working days on the reconstruction of the three exhibited seismographs. Protective cabinets around the instruments were mounted in November 2005.