Aseismic faulting following the 1973 Nemuro-Oki earthquake, Hokkaido, Japan (a possibility)
Aseismic faulting following the 1973 Nemuro-Oki earthquake, Hokkaido, Japan (a possibility)
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1973 年日本北海道根室冲地震后的抗震断层（可能）
DOI：
10.1007/bf01592905
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发表时间：
1975
期刊：
影响因子：
--
通讯作者：
K. Kasahara
中科院分区：
文献类型：
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作者：
K. Kasahara
本文结合1973年6月17日日本北海道根室半岛外地震，研究了主震后地震断层延迟应变释放的可能性。本文的主要目的是全面了解北海道东部地区的地壳运动与地震周期的关系。该地区，特别是根室半岛地区，在过去的几十年里遭受了广泛的地面沉降。例如，在花崎，在过去的70年里，它达到了-60厘米。根据古海平面的残留标志，在过去的5000-6000年里，同一地区的长期沉降累积只有-2米。因此，从地貌学的证据可以看出，现代陆移的速率是长期陆移速率的20倍或更多。这两种速率之间的这种不一致使我们预期未来的隆起阶段将补偿先前的沉降。为了解释从花崎潮汐记录推断的前根室冲地震（1894年），提出了由地震断层延迟应变释放的建议。该模型基本上是一个复合断裂系统，在板块边界的一定深度处具有脆-韧性转换。如果是这样的话，花崎的验潮仪将在未来几年内记录到1973年地震后40厘米或更高的显著陆地隆起。从地震预报的观点来看，韧性部分的滑动方式是一个值得关注的问题，因为如果断层快速滑动，可能会发生二次地震。最近在Hanasaki的海平面变化似乎表明裂缝在下倾方向缓慢扩展。此外，还对板边界的流变特性作了简要讨论，以估算粘滞系数，供今后参考。
The possibility of delayed strain release by aseismic faulting following a main shock is studied in relation to the recent earthquake off Nemuro peninsula, Hokkaido, Japan 17 June, 1973. The main purpose of this paper is to obtain a comprehensive view of the land movement in eastern Hokkaido with respect to the seismic cycle there This region, particularly the Nemuro peninsula area, has been subject to extensive land subsidence in the past several decades. At Hanasaki, for example, it amounted to −60 cm in the past 70 years. The long-term accumulation of subsidence in the same area, as read from remaining marks of the ancient sea level, is only −2 m in the past 5000–6000 years. There-fore, the rate of the recent land movement is twenty times or more as high as the long-tern one, which is known from the geomorphological evidence. Such disagreement between the two kinds of rates leads us to expect a future uplift phase which will compensate the previous subsidence.Delayed strain release by aseismic faulting is suggested in order to account for the former Nemurooki earthquake (1894) as inferred from the tidal record at Hanasaki. The model is basically a compound fault system with brittle-ductile transition at a certain depth in the plate boundary. If this were the case, the tide-gauge at Hanasaki would record a significant land uplift following the 1973 earthquake for 40 cm or more in the forthcoming several years. The slip mode in the ductile part is a matter of concern from the viewpoint of earthquake prediction, as a secondary shock may occur if the fault should slip quickly. The recent sea-level change at Hanasaki seems to suggest slow propagation of fracture in the down-dip direction. A brief discussion is added on the rheological properties of the plate boundary to estimate the viscosity coefficient for future reference.