Earthquake activity in the greater New York City area: Magnitudes, seismicity, and geologic structures
Earthquake activity in the greater New York City area: Magnitudes, seismicity, and geologic structures
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大纽约地区的地震活动：震级、地震活动和地质结构
DOI：
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发表时间：
1985
期刊：
影响因子：
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通讯作者：
N. Barstow
中科院分区：
文献类型：
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作者：
A. Kafka;E. Schlesinger;N. Barstow
摘要本文分析了大纽约地区Lamont-Doherty地震台网台站记录的地震，以确定震级以及地震活动与地质构造的关系。1974年至1983年期间，该区域监测站的配置保持相对稳定，记录设备（可视鼓记录器和16毫米照相记录器）的类型没有改变。这种台站和记录设备的分布使得震级和地震活动的测量统一。这些地震的震级是通过比较本地网络记录的高频（5至10赫兹）数据测量的振幅和信号持续时间，以及从频率接近1赫兹的数据确定的m bLg和m L来确定的。研究期间（近10年），本区共发生61次地震，但均未超过3.0级。最大的一次（m bLg = 3.0）发生在新泽西州北部的沿海平原省。在研究期间，对整个地区的事件进行均匀探测的震级阈值估计为m bLg = 1.6。将低于该阈值的事件从网络地震活动目录中删除后，我们发现所研究的地震中约有一半发生在Ramapo断层系统10公里范围内。这个断层系统位于纽约市西北约30公里处，几位研究人员将其解释为大纽约市地区最活跃的断层系统。然而，至少与拉马波断层附近记录的地震一样大的地震发生在距离该断层50公里远的地方（距离纽约市20公里以内），位于纽瓦克盆地周围的地质构造中。虽然不能排除Ramapo断层是大纽约地区地震的可能震源区，但与该地区大多数（如果不是全部）地震相关的地质结构仍然未知。因此，这个地区地震的原因仍然是个谜。
Abstract Earthquakes recorded by stations of the Lamont-Doherty seismic network in the greater New York City area are analyzed to determine magnitudes and the relationship between seismicity and geologic structures. Between 1974 and 1983, the configuration of stations in this region remained relatively stationary and the type of recording devices (visual drum recorders and 16-mm photographic recorders) did not change. This distribution of stations and recording devices allows for a uniform measurement of magnitudes and seismicity. Magnitudes of these earthquakes are determined by comparing amplitudes and signal duration measured from high-frequency (5 to 10 Hz) data recorded by the local network with m bLg and M L determined from data at frequencies near 1 Hz. During the period of time studied (nearly 10 yr), 61 earthquakes were located in this region, but none of these earthquakes exceeded 3.0 on the m bLg scale. The largest event ( m bLg = 3.0) occurred in the Coastal Plain province of northern New Jersey. The magnitude threshold for uniform detection of events throughout this region during the period of time studied is estimated to be m bLg = 1.6. With events below this threshold removed from the catalog of network seismicity, we find that about half of the earthquakes studied occurred within 10 km of the Ramapo fault system. This fault system lies about 30 km northwest of New York City and has been interpreted by several investigators to be the most active fault system in the greater New York City area. However, earthquakes at least as large as those recorded near the Ramapo fault were located as far as 50 km from this fault (and within 20 km of New York City), in geologic structures that surround the Newark basin. While the Ramapo fault can by no means be ruled out as a possible source zone for earthquakes in the greater New York City area, the geologic structures associated with most (if not all) earthquakes in this region are still unknown. Thus, the cause of earthquakes in this region remains an enigma.