Anomalous pre-seismic transmission of VHF-band radio waves resulting from large earthquakes, and its statistical relationship to magnitude of impending earthquakes
Anomalous pre-seismic transmission of VHF-band radio waves resulting from large earthquakes, and its statistical relationship to magnitude of impending earthquakes
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DOI：
10.1111/j.1365-246x.2009.04461.x
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发表时间：
2010-02-01
影响因子：
2.8
通讯作者：
Takada, M.
中科院分区：
文献类型：
--
作者：
Moriya, T.;Mogi, T.;Takada, M.
为了确认VHF频段无线电波的异常传输与即将发生的地震之间的关系，我们设计了一种新的数据收集系统，并记录了自2002年12月以来日本北部北海道地震发生前VHF频段无线电波超出视距的异常传播情况。在两次大地震（2003 年 9 月 26 日的十胜冲地震（M(j) = 8.0，M(j)：日本气象厅定义的震级）和 2004 年 12 月 14 日的南部留萌县地震（M(j) = 6.1））之前记录到了异常 VHF 频段无线电波。从给定 FM 广播电台发射的无线电波被认为是分散的，因此它们可以对于2004年6月和2005年8月在北海道日高山下48-54 km深度发生的M4-M5级地震，异常传输总持续时间（Te）的对数与临震震级（M）或最大地震烈度（I）之间建立了线性关系。类似的线性关系对于发生在不同深度的地震也有效。对于较浅的地震，这种关系变为较长的 Te，对于较深的地震，这种关系变为较短的 Te。许多参数似乎都会影响Te，包括震源深度和震中区域（即海洋或陆地）的表面条件。这种关系很重要，因为它意味着 VHF 波段波的震前异常传输可能有助于预测即将发生的地震的规模。
To confirm the relationship between anomalous transmission of VHF-band radio waves and impending earthquakes, we designed a new data-collection system and have documented the anomalous VHF-band radio-wave propagation beyond the line of sight prior to earthquakes since 2002 December in Hokkaido, northern Japan. Anomalous VHF-band radio waves were recorded before two large earthquakes, the Tokachi-oki earthquake (M(j) = 8.0, M(j): magnitude defined by the Japan Meteorological Agency) on 2003 September 26 and the southern Rumoi sub-prefecture earthquake (M(j) = 6.1) on 2004 December 14. Radio waves transmitted from a given FM radio station are considered to be scattered, such that they could be received by an observation station beyond the line of sight.A linear relationship was established between the logarithm of the total duration time of anomalous transmissions (Te) and the magnitude (M) or maximum seismic intensity (I) of the impending earthquake, for M4-M5 class earthquakes that occurred at depths of 48-54 km beneath the Hidaka Mountains in Hokkaido in 2004 June and 2005 August. Similar linear relationships are also valid for earthquakes that occurred at different depths. The relationship was shifted to longer Te for shallower earthquakes and to shorter Te for deeper ones. Numerous parameters seem to affect Te, including hypocenter depths and surface conditions of epicentral area (i.e. sea or land). This relationship is important because it means that pre-seismic anomalous transmission of VHF-band waves may be useful in predicting the size of an impending earthquake.