Our scheme is developed mostly on ambient noise recordings and, thus, surface waves. We propose a simple working scheme to identify the existence of potential installation‐related issues and to assess the frequency fidelity range of response of a seismic station to ground motion. Using examples from seismometric and accelerometric stations, we describe the (1) housing, (2) foundation, and (3) pillar effects on the seismic records. Not the same level of attention is commonly dedicated to the seismic station installation, to the point that it is generally believed that housings and shelters containing seismic instruments are of no interest, because they can only affect frequencies well above the engineering range of interest. #Seismac stations series#Consequently, increasing attention is paid to the assessment of the geophysical properties of the soils at the seismic stations, which impact the station recordings and a series of related quantities, particularly those referring to seismic hazard estimates. Journal of the Earth&Space Physics, 31(1), 13-21.The role of local geology in controlling ground motion has long been acknowledged. Magnitude scale in the Tabriz seismic network. Journal of Geophysical Research,78, 876-855. Seismic wave attenuation relations for eastern NorthAmerica. Where, is the maximum amplitude in nanometers per second and is epicentral distance in kilometers. The magnitude of earthquakes is reported in the corrected Nuttli (1973) magnitude scale (Rezapour, 2005): Our Short period seismic stations are equipped with SS1 seismometers, the medium- bands are equipped with Trillium-40s seismometers, and broad-bands are equipped with CMG3ESP-120s, CMG3T-360s and Trillium-240s seismometers. Recorded data in all stations in the country are transmitted to the center of each seismic local network, which relays the data to the Iranian seismological center continuously by VPN or Satellite communications. Seismic local networks are developing and expanding according to our short-term, medium-term, and long-term plans. Today, the Iranian seismological network comprises 108 digital seismic stations in 20 seismic local networks, 4 digital seismic stations and 1 borehole stations which cover most earthquake-prone regions (Figure 1).įigure 1 Seismic local networks of the Iranian seismological network Seismic stations are equipped with three (3) component short-period, medium-band or broad-band seismometers. The new seismic local networks of Minab, Kerman, Shahr-e-Kord and Hamedan were installed in 2010. Digital seismological equipment was supplied and installed in Tehran and Tabriz seismic local networks in 1995, and gradually the local networks of Semnan, Quchan, Yazd, Sari, Esfahan, Shiraz, Mashhad, Kermanshah, Birjand and Khoram-abad in turn were installed and equipped with digital instruments. Until 1995, the above mentioned analogue stations were responsible for recording and reporting earthquake events throughout the nation. In the early 1981s, some additional analogue stations were installed at Brojen, Minoodasht, Mahabad, Ghamsar-e-Kashan and Ghaleh-Ghazi by Institute of Geophysics. The Iranian Long Period Array (ILPA) consisted of seven (7) stations installed in the south-west of Tehran in 1975. The stations of Tabriz, Mashhad and Shiraz were a subset of the World-Wide Standardized Seismographic Network (WWSSN). In the 1960s, the number of seismic stations increased to five (5) analogue stations installed in the cities of Tehran, Tabriz, Mashhad, Shiraz and Kermanshah. The Institute of Geophysics, affiliated with the University of Tehran, constructed the first seismic station in Tehran in 1958, to record and locate earthquakes. Seismic Local Networks of the Iranian Seismological Center Basic Parameters of Earthquakes in Iran (~2000)
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