Historical and recent seismic activity in South Carolina
Historical and recent seismic activity in South Carolina
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南卡罗来纳州历史和近期的地震活动
DOI：
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发表时间：
1972
期刊：
影响因子：
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通讯作者：
G. Bollinger
中科院分区：
文献类型：
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作者：
G. Bollinger
南卡罗来纳州的地震史主要是1886年8月31日的查尔斯顿大地震。除了有几个不寻常的方面（该地区基本上没有地震前200年，大毛毡面积，双震中点，“低强度区”在西弗吉尼亚州），强度X事件严重扰乱了该地区的地震制度，至少在随后的30年。在1754年至1971年期间，该州报告发生的438次地震中，有402次发生在查尔斯顿-萨默维尔地区。剩下的36个地震形成了一个东南走向的活动区，横向于阿巴拉契亚山脉的结构颗粒。
对于1886-1971年的60次地震，最大烈度为I 0的地震数N与IV ~ I 0 ~ VIII的关系为logN = 0.52- 0.31I0。这对应于log N与M关系中的“B”值0.5 ± 0.1，假设M = 1 +（2/3）I 0。这些数据表明，地震活动的频率与新马德里地震带报告的频率相当。
1971年夏天，在查尔斯顿地区进行了三个月的微震监测，获得了505小时的低噪声数据。记录到61次地震，主要是群震。这些微冲击事件的h值为1.8 ± 0.5。这个值与以前在新泽西观测到的震群序列相似。
1971年，该州发生了四次地震。其中三次（5月19日、7月31日、8月11日）发生在该州中部靠近奥兰治堡的地方，而第三次（7月13日）发生在南卡罗来纳州西北部的塞涅卡附近。所有三个事件均为3.0 < ML < 4.0。1956年和1965年也发生过类似的事件，一年内发生三次或四次冲击。根据历史资料，奥兰治堡地区以前没有地震震中。
The seismic history of South Carolina is dominated by the great Charleston earthquake of August 31, 1886. In addition to having several unusual aspects (region essentially free from shocks for preceding 200 years, large felt area, dual epicenter points, “low intensity zone” in West Virginia), that intensity X event seriously perturbed the seismic regime of the area for at least the following 30 years. Of 438 earthquakes reported to have occurred in the state between 1754 and 1971, 402 have been in the Charleston-Summerville area. The remaining 36 shocks form a southeasterly-trending zone of activity that is transverse to the structural grain of the Appalachians.
For the 60 shocks assigned an intensity value (1886-1971), a recurrence relationship between the number of earthquakes “N” of maximum intensity “I0” was found to be log N = 0.52-0.31 I0 for IV ≦ I0 ≦ VIII. This corresponds to a “b” value of 0.5 ± 0.1 in log N versus M relationship assuming M = 1 + (2/3)I0. These data suggest a frequency of seismic activity comparable to that reported for the New Madrid seismic zone.
Three months of microearthquake monitoring in the Charleston area during the summer of 1971 yielded 505 hr of low-noise data. Sixty-one earthquakes, primarily in swarm occurrence, were recorded. An h value of 1.8 ± 0.5 was determined for these microshock events. This value is similar to that previously observed for a swarm sequence in New Jersey.
Four shocks occurred in the state during 1971. Three of these events (May 19, July 31, August 11) were in the central part of the state near Orangeburg, while the third event (July 13) was near Seneca in northwestern South Carolina. All three events had 3.0 < ML < 4.0. Similar episodes of three or four shocks in 1 year happened in 1956 and again in 1965. The Orangeburg area had, according to historical data, been previously free of earthquake epicenters.