Determination of the onset time in polarization power ratio Z/H for precursor of Sumatra earthquake

• Main Authors: Ahadi, S, Puspito, N T, Ibrahim, G, Saroso, S
• Format: Conference Proceeding
• Language: English
• Subjects: AMPLITUDES; Earthquake prediction; EARTHQUAKES; ELECTROMAGNETIC RADIATION; EMISSION; Frequency spectrum; GEOMAGNETIC FIELD; Geomagnetism; GEOPHYSICS; GEOSCIENCES; PATTERN RECOGNITION; POLARIZATION; PRECURSOR; Precursors; Seismic activity; SEISMICITY; Seismograms; SIGNALS; Standard deviation; Vertical polarization
• ISSN: 0094-243X; 1551-7616
• DOI: 10.1063/1.4897108

Determination of onset time precursors of strong earthquakes (Mw > 5) and distance (d < 500 km) using geomagnetic data from Geomagnetic station KTB, Sumatra and two station references DAV, Philippine and DAW, Australia. separate techniques are required in its determination. Not the same as that recorded in the kinetic wave seismograms can be determined by direct time domain. Difficulties associated with electromagnetic waves seismogenic activities require analysis of the transformed signal in the frequency domain. Determination of the frequency spectrum will determine the frequency of emissions emitted from the earthquake source. The aim is to analyze the power amplitude of the ULF emissions in the horizontal component (H) and vertical component (Z). Polarization power ratio Z/H is used for determining the sign of earthquake precursors controlled by the standard deviation. The pattern recognition polarization ratio should be obtained which can differentiate emissions from seismogenic effects of geomagnetic activity. ULF emission patterns generated that seismogenic effect has duration > 5 days and the dominance of emission intensity recorded at the Z component and for the dominance of the emission intensity of geomagnetic activity recorded in the component H. The result shows that the onset time is determined when the polarization power ratio Z/H standard deviation over the limit (p ± 2 σ) which has a duration of > 5 days.