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本文报道了台湾实时地震监测的最新进展,尤其是台湾中心气象局遥测地震台网(CWBSN)的实时强震监测。该项工作旨在大震发生后迅即速报。如果速报能在强振动到来之前完成,那么地震早期警报将成为可能。CWBSN已能在大震发生后一分钟内给出强度图、震中和震级。速报和早期警报主要适用于大震(M>>5);不限幅波形记录的需要促使CWBSN在1995年将强震探测仪(如力平衡加速度计)并入其遥测地震监测系统中。将时间域递归处理应用于多道输入地震信号,通过一组联网微机生成强度图。通过等值线,能迅速识别出位于强度图最大等值线(通常为100gal)中央的有效震中。有效震级也能迅速由最大等值线(通常为100gal)覆盖的表面积确定。对于具有有限破裂面的大震,如此得出的震中和震级是更适当的震源位置和破坏强度的估算值。有效震中给出了破坏区域的中心,与传统的震中定位比较,后者仅给出了破裂形成的初始位置。有效震级所反映的更接近地震破坏的潜能,而不是强调总能量释放的传统震级。CWBSN已能在一分钟内获取上述震源的关键信息。这一时间将会进一步缩短至30s以内,如本文中举例描述的那样,地震早期警报的确是一个可能达到的目标。速报和早期警报信息将电传给用户,以采取人为或无人干予的快速反应行动。
This paper reports the latest developments in real-time seismic monitoring in Taiwan, in particular, the real-time strong earthquake monitoring of Taiwan Central Meteorological Bureau Telemetry Seismograph Network (CWBSN). This work aims to promptly report immediately after the earthquake. Early warning of an earthquake will be possible if the breakup can be completed before the strong vibration arrives. CWBSN has been able to give intensity maps, epicenter and magnitude within one minute of a major earthquake. Quick reports and early warnings are mainly applicable to large earthquakes (M >> 5); the need for unwrapped waveform recording prompted CWBSN to incorporate a strong seismic detector (such as a force balance accelerometer) into its telemetry seismic monitoring system in 1995. The time-domain recursive processing applied to multi-channel input seismic signals, through a set of networking computer generated intensity map. By contouring, an effective epicenter centered on the largest contour of the intensity map (typically 100 gal) can be quickly identified. The effective magnitude can also be rapidly determined by the surface area covered by the largest contour (typically 100 gal). For large earthquakes with a finite fracture surface, the epicenter and magnitude thus obtained are more appropriate estimates of source location and failure strength. The effective epicenter gives the center of the damaged area, which is compared with the traditional epicentral location, the latter only gives the initial location of the rupture. Instead of emphasizing the traditional magnitude of total energy release, the effective magnitude reflects the potential for closer earthquake damage. CWBSN has been able to obtain the key information from the above source in less than a minute. This time will be further reduced to less than 30 seconds, as the examples in this article illustrate, early warning of the earthquake is indeed a possible goal. Newsletters and early warning messages are relayed to users for quick response, either man-made or unmanned.