Accession Number:

AD0628023

Title:

BACKGROUND NOISE ON THE S. S. S. STANDARD INSTRUMENTS (RUIDO DE FONDO EN LOS SISMOGRAFOS STANDARD DEL SERVICIO DE SISMOLOGIA),

Descriptive Note:

Corporate Author:

INSTITUTO GEOGRAFICO Y CATASTRAL MADRID (SPAIN)

Personal Author(s):

Report Date:

1964-01-01

Pagination or Media Count:

62.0

Abstract:

A study of noise observed on the Toledo and Malaga seismographs of the World-wide Standarized Seismograph Network is given. For both sets of instruments, LP and SP, the noise is classified in microseisms and disturbances. The spectrum of LP and SP microseisms is obtained and compared with previous data. A minimum of the amplitude in the neighborhood of 2 cps, already observed at many sites of the USA, is also shown for Toledo and Malaga whereas the maximum of the spectrum around 4 - 8 sec, established by Brune and Oliver and considered by them as a major result of observational seismology is not clearly defined. Annual variation of microseismic period and amplitude is analyzed and the ratio AHAZ derived such ratio is used for computing the thickness of the sedimentary layer at the observatories. Observation shows the existence of a predominant period of microseisms at the two places considered. The data include periods greater than 0.4 sec only, since the instruments are not sensitive enough for recording shorter period microseisms but they show a clear distinction between the period distribution curves of Toledo and Malaga, which is explained in terms of difference in geologic structure. LP disturbances are correlated with wind and movement of people inside the Observatory. A very near origin inside the vault, perhaps in the seismometer is suggested for pulses observed on the three LP components. SP disturbances, on the other hand, are seen to be produced partly by traffic along nearby road. Author

Subject Categories:

  • Seismology
  • Seismic Detection and Detectors

Distribution Statement:

APPROVED FOR PUBLIC RELEASE