ULF electromagnetic precursors for an earthquake at Biak, Indonesia on February 17, 1996

Citation
M. Hayakawa et al., ULF electromagnetic precursors for an earthquake at Biak, Indonesia on February 17, 1996, GEOPHYS R L, 27(10), 2000, pp. 1531-1534
Citations number
14
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Earth Sciences
Journal title
GEOPHYSICAL RESEARCH LETTERS
ISSN journal
0094-8276 → ACNP
Volume
27
Issue
10
Year of publication
2000
Pages
1531 - 1534
Database
ISI
SICI code
0094-8276(20000515)27:10<1531:UEPFAE>2.0.ZU;2-Q
Abstract
ULF electromagnetic emissions associated with a large earthquake occurred a t Biak Island, Indonesia at 5h 59m UT on February 17, 1996 (magnitude (Mw) = 8.2 and depth = 20 km from USGS catalog), have been investigated on the b asis of ULF magnetic observations at two stations, Biak and Darwin in Austr alia (about 1,200 km apart). Though a simple analysis of magnetic field int ensity (horizontal and vertical magnetic field components) at both stations was found to be closely correlated with geomagnetic Sigma Kp activity, a d etailed analysis of the difference of H and Z components at the two station s, the polarization analysis (Z/H) and fractal analysis (frequency spectrum slope) at these two stations has yielded that the ULF emissions (in the fr equency range from 5 mHz to 30 mHz) about 1.5-1.0 months before the quake a re likely to be a precursory signature of the quake with its intensity on t he order of 0.2-0.3 nT.