Department of Hydraulic and Ocean Engineering, National Cheng Kung University, Tainan 70101, Taiwan.
National Science and Technology Center for Disaster Reduction, New Taipei City 23143, Taiwan.
Sensors (Basel). 2022 Nov 29;22(23):9310. doi: 10.3390/s22239310.
A lab-fabricated ocean bottom seismometer was modified and deployed terrestrially to detect low-frequency (<10 Hz) ground vibrations produced by debris flows. A frequency−response test of the new seismometer revealed that it can detect seismic signals at frequencies of 0.3−120 Hz. Its seismic ground motion detection ability was investigated by comparing its measurements of seismic signals produced by rockfalls with those of a geophone. Two new seismometers were deployed at the Aiyuzi Stream, Nantou County, Taiwan, in September 2012. Seismic signals produced by two local earthquakes, two teleseisms, and three debris flows detected by the seismometer in 2013 and 2014 were discussed. The seismic signal frequencies of the local earthquakes and teleseisms (both approximately 1800 km apart) were 0.3−30 and <1 Hz, respectively. Moreover, seismometer measurements revealed that seismic signals generated by debris flows can have minimum frequencies as low as 2 Hz. Time-matched CCD camera images revealed that debris flow surge fronts with larger rocks have lower minimum frequencies. Finally, because the seismometer can detect low-frequency seismic waves with low spatial decay rates, it was able to detect one debris flow approximately 3 min and 40 s before it arrived.
实验室制造的海底地震仪经过改装并在陆地上部署，用于探测由碎屑流产生的低频（<10 Hz）地面振动。新地震仪的频率响应测试表明，它可以探测到 0.3-120 Hz 的地震信号。通过比较其对岩石崩塌产生的地震信号的测量结果与地震计的测量结果，研究了其地震地面运动探测能力。两台新的地震仪于 2012 年 9 月在台湾南投县的 Aiyuzi 溪部署。讨论了地震仪在 2013 年和 2014 年探测到的两次当地地震、两次远震和三次碎屑流产生的地震信号。当地震和远震（相隔约 1800 公里）的地震信号频率分别为 0.3-30 和<1 Hz。此外，地震仪测量结果表明，碎屑流产生的地震信号的最小频率可低至 2 Hz。时间匹配的 CCD 相机图像显示，具有较大岩石的碎屑流涌浪前缘的最小频率较低。最后，由于地震仪可以探测到空间衰减率较低的低频地震波，因此它能够在大约 3 分 40 秒前探测到一次碎屑流。
