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对只有几个台站记录到的区域地震的定位,用以走时为基础的定位方法是不理想的。然而,全面禁止核试验条约要求我们必须用很少的观测来监测地震事件。本文考察了单台定位方法的现状,即:使用三分向宽频带数字化台站的记录对地震事件定位。这里我们讨论的单台定位方法,最终可以是监测地球上大部分地区小震级(M～3)地震事件最有效最经济的手段。使用宽频带三分向观测资料和合成波形的拟合,可准确地确定震中距和震源深度。台站到地震的方位角可由P波偏振和P波尾波确定。但是,单台定位方法实际成为一种接替走时方法之前,需要做更多的研究工作。目前最重要的问题是区域地震图和区域地壳构造有很强的相关性,这样,将来的研究重点应在确定对具体区域合适的地壳模型和改进方法以处理地壳构造的区域变化。第二个重要问题是定位误差,用单台定位时,台站至地震的方位角可以有180°的误差或其他更大的非高斯“误差”。
For the location of regional earthquakes recorded by only a few stations, the time-based positioning method is not ideal. However, the Comprehensive Nuclear-Test-Ban Treaty requires that we must monitor earthquakes with very few observations. This article examines the current status of single-station positioning methods, namely the location of seismic events using records from tridimensional broadband digital stations. The single positioning method we are discussing here can eventually be the most effective and economical means of monitoring earthquakes of small magnitude (M ~ 3) in most parts of the earth. Using the broadband tridimensional observations and the fitting of the resultant waveforms, the epicentral distance and focal depth can be accurately determined. Azimuth from station to earthquake can be determined by P-wave polarization and P-wave wake. However, more research needs to be done before a single positioning method actually becomes a successor way. At present, the most important issue is that there is a strong correlation between regional seismograms and regional crustal structures. Therefore, future studies should focus on identifying suitable crustal models for specific regions and improving methods to deal with the regional changes in the crustal structure. The second important issue is the positioning error. With a single positioning, the azimuth of the station-to-earthquakes can have a 180 ° error or other larger non-Gaussian “error”.