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图 1 地震预警(EEW)相关延迟概述。各延迟分量含义见表1。柱状图长度代表瑞士地震台网和VS(SC3)的实测延迟。竖直虚线标出了进行震源估算所需的足够P波到达的时间。示例中,台站n对震级估算没有帮助,因为在首次定位预测时尚未得到足够的波形数据(
$\Delta {t_{\rm origin}}$ )(原图为彩色)图 3 与图2相同,但为加利福尼亚地区。这里的颜色表示P波传播到在加州运行的3个地震台网中的4个宽频台站的时间。三角形标记了实时宽频台站的位置,灰线表示5 s和10 s的等时线。插图显示的是加州所有的地震台网合并后的
$\max (\overrightarrow {\Delta {t_{\rm p}}} )$ (原图为彩色)图 4 VS(SC3)系统(a,c,e,g,i为瑞士)及VS(EW)系统(b,d,f,h,j为加利福尼亚)测量延迟总结。b,d,f,h,j中的插图为图1的简化版,黑色线框内表示的是各自子图内的延迟。(a,b)分别为所有台站i实时发送数据至瑞士和加州台网的时间
$\Delta {t_{{\rm l},i}}$ 的分布;(c,d)为实时运行过程中测量的$\Delta {t_{{\rm w},i}}$ ;(e,f)为$\Delta {t_{{\rm t},i}}$ 的分布;(g)为2012年10月到2013年10月发生在瑞士和相邻区域的289次震级≥1.5的地震事件实时测量的$\Delta {t_{\rm a}}$ 的分布;(h)与(g)相同,但为2010年1月到2012年8月发生在加州南部的119次震级≥3.5的地震事件测试;(i)为2009年1月到2013年6月发生在瑞士和相邻区域的97次震级≥2.5的地震事件离线测试测量的$\Delta {t_{\rm m}}$ ;(j)与(i)相同,但是通过对与(h)相同的119次地震事件的离线测试测量得到的。所有直方图都是归一化的(原图为彩色)图 6 与图5相同,但为加利福尼亚地区。圆圈表示2012年1月到2013年12月实时准确检测到的震级≥3.5的56次地震事件位置;白色、灰色和黑色三角形分别表示加利福尼亚地震台网管理与接收数据的宽频强震台站位置;黑色虚线表示粗略地划分加利福尼亚南北地震台网的Gutenberg– Byerly线(原图为彩色)
图 7 用2个代替6个P波检测来计算首次定位所减少的报警时间。不同颜色表示较图(5a)描述时间减少报警时间的中位数。注意到瑞士台网最密集的部分几乎没有任何提高,但在密度较小的地区,预警时间可减少5—6 s(原图为彩色)
图 8 在加利福尼亚南部地震台网假设数据延迟比目前实测值少0.5—2.5 s时报警时间的减少量。不同颜色表示图(6a)中所示的报警时间减少量的中位数。在台网部分区域报警时间变化量可达5 s,在洛杉矶盆地约为1 s(原图为彩色)
表 1 “定义地震预警系统中的延迟”中描述的不同延迟分量的详细解释,包括延迟影响因素以及在该研究中的测量方法
延迟 描述 影响因素 测量方法 $\Delta {t_{\rm alert}}$ 发震时间与地震预警信息到达目标区的时间差 $\overrightarrow {\Delta {t_{\rm p}}} ,\overrightarrow {\Delta {t_{\rm t}}} ,\overrightarrow {\Delta {t_{\rm w}}} ,\Delta {t_{\rm a}},\Delta {t_{\rm m}},\Delta {t_{\rm d}}$ 地震日志文件(使用观测延迟对预期报警时间部分进行建模) $\Delta {t_{\rm origin}}$ 发震时间与首次获取震源
估计的时间差$\overrightarrow {\Delta {t_{\rm p}}} ,\overrightarrow {\Delta {t_{\rm t}}} ,\Delta {t_{\rm a}}$ 无法明确测量 $\overrightarrow {\Delta {t_{\rm p}}} $ P波到达前n个台站的传播时间 台网形状和震源位置 合成传播时间(“P波传播时间 $\overrightarrow {\Delta {t_{\rm p}}} $ ”
部分)$\overrightarrow {\Delta {t_{\rm t}}} $ P波到达前n个台站与P波触发/检波的时间差 $\overrightarrow {\Delta {t_{\rm l}}} ,\Delta {t_{\rm pk}}$ 连续日志文件(“触发延迟 $\overrightarrow {\Delta {t_{\rm t}}} $ ”
部分)$\overrightarrow {\Delta {t_{\rm l}}} $ 前n个台站每个台站的数据延迟 $\overrightarrow {\Delta {t_{\log }}} ,\overrightarrow {\Delta {t_{\rm trans}}} ,\Delta {t_{\rm rec}}$ 连续日志文件(“数据延迟 $\overrightarrow {\Delta {t_{\rm l}}} $ ”部分)$\overrightarrow {\Delta {t_{\log }}} $ 前n个台站数采的处理和打包时间 数采型号和配置(如采样率) 无法单独测量 $\overrightarrow {\Delta {t_{\rm trans}}} $ 前n个台站到数据中心的传播延迟 通讯系统,采样率 无法单独测量 $\Delta {t_{\rm rec}}$ 数据中心接收队列与处理延迟 接收软件 无法单独测量 $\Delta {t_{\rm pk}}$ 自动捡拾器处理延迟 EEW软件 无法单独测量 $\Delta {t_{\rm a}}$ 地震确认和使用前n个P波检测发布报警信息的处理延迟 EEW软件 地震日志文件(“地震确认延迟( $\Delta {t_{\rm a}}$ )”部分)$\overrightarrow {\Delta {t_{\rm w}}} $ 前n个台站每个台站的P波到时与获取k秒波形数据进行震级估算的时间差 $\overrightarrow {\Delta {t_{\rm l}}} ,\Delta {t_{\rm win}}\left( k \right),\Delta {t_{\rm pw}}$ 连续日志文件( “波形延迟( $\overrightarrow {\Delta {t_{\rm w}}} $ )”
部分)$\Delta {t_{\rm win}}\left( k \right)$ k秒长波形时窗 EEW软件 配置设置 $\Delta {t_{\rm pw}}$ 波形数据预处理 EEW软件 无法单独测量 $\Delta {t_{\rm m}}$ 使用获取的定位信息与波形数据计算EEW震级的处理延迟 EEW软件 地震日志文件(“震级估算时间( $\Delta {t_{\rm m}}$ )”部分)$\Delta {t_{\rm d}}$ 发布报警信息的传输延迟 通讯系统和终端用户互联网连接 未测量 -
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