The numerical results showed that if the monument presents, after its restoration, all the basic conditions favourable for its stability (i.e. The analyses included, among others, an investigation of the influence of the monument’s rubble core on its seismic response. 3-D numerical analyses were performed using the FE software Abaqus and records of four earthquakes suitably scaled. The examined structure corresponds to the proposed restoration. Seismograms are digital now - there are no more paper recordings.This paper presents a sophisticated numerical investigation of the seismic stability of a ruinous section of the city walls of ancient Messene (Peloponnese, Greece), which has been recently proposed to be partially but extensively restored. When there is NO EARTHQUAKE reading, there is just a straight line except for small wiggles caused by local disturbance or 'noise' and the time markers.

In reality, these mechanisms are no longer manual, but instead work by measuring electronic changes produced by the motion of the ground with respect to the mass.Ī seismogram is the recording of the ground shaking at the specific location of the instrument. On a seismogram, the HORIZONTAL axis = time (measured in seconds) and the VERTICAL axis= ground displacement (usually measured in millimeters). As the seismograph shakes under the mass, the recording device on the mass records the relative motion between itself and the rest of the instrument, thus recording the ground motion. This did not, however, record earthquakes it only indicated that an earthquake was occurring. The first seismograph was developed in 1890.Ī seismograph is securely mounted onto the surface of the earth so that when the earth shakes, the entire unit shakes with it EXCEPT for the mass on the spring, which has inertia and remains in the same place. The earliest 'seismoscope' was invented by the Chinese philosopher Chang Heng in A.D. They are installed in the ground throughout the world and operated as part of a seismographic network. Seismographs are instruments used to record the motion of the ground during an earthquake. A seismometer is the internal part of the seismograph, which may be a pendulum or a mass mounted on a spring however, it is often used synonymously with 'seismograph'.

Seismosignal negative displacements