Fialko Yuri
Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, USA.
Nature. 2006 Jun 22;441(7096):968-71. doi: 10.1038/nature04797.
The San Andreas fault in California is a mature continental transform fault that accommodates a significant fraction of motion between the North American and Pacific plates. The two most recent great earthquakes on this fault ruptured its northern and central sections in 1906 and 1857, respectively. The southern section of the fault, however, has not produced a great earthquake in historic times (for at least 250 years). Assuming the average slip rate of a few centimetres per year, typical of the rest of the San Andreas fault, the minimum amount of slip deficit accrued on the southern section is of the order of 7-10 metres, comparable to the maximum co-seismic offset ever documented on the fault. Here I present high-resolution measurements of interseismic deformation across the southern San Andreas fault system using a well-populated catalogue of space-borne synthetic aperture radar data. The data reveal a nearly equal partitioning of deformation between the southern San Andreas and San Jacinto faults, with a pronounced asymmetry in strain accumulation with respect to the geologically mapped fault traces. The observed strain rates confirm that the southern section of the San Andreas fault may be approaching the end of the interseismic phase of the earthquake cycle.
加利福尼亚州的圣安德烈亚斯断层是一条成熟的大陆转换断层，它承受了北美板块和太平洋板块之间相当一部分的运动。该断层上最近的两次大地震分别于1906年和1857年使其北段和中段发生破裂。然而，该断层的南段在历史时期（至少250年）尚未发生过大地震。假设南段的滑动速率与圣安德烈亚斯断层其他部分典型的每年几厘米的平均滑动速率相同，那么南段累积的最小滑动亏损量约为7至10米，这与该断层有记录以来的最大同震位移相当。在此，我利用丰富的星载合成孔径雷达数据目录，给出了圣安德烈亚斯断层系统南段跨震间变形的高分辨率测量结果。数据显示，圣安德烈亚斯断层南段和圣哈辛托断层之间的变形分配几乎相等，且相对于地质测绘的断层迹线，应变积累存在明显的不对称性。观测到的应变率证实，圣安德烈亚斯断层南段可能正接近地震周期的震间阶段末期。
