image: Water storage estimated from the regional GPS network throughout central and northern California shown as average water-layer thickness on a 25 km grid. The summer months experience a loss of water in the Sierra Nevada and Central Valley that is replenished in the mountains during the wet winter months as reservoirs fill and snow accumulates. In the Central Valley, water storage has been continuously decreasing due to large scale agriculture. The seasonal change in mass deforms the crust and the associated stress changes modulate regional seismicity. This material relates to a paper that appeared in the 16 June 2017, issue of <i>Science</i>, published by AAAS. The paper, by C.W. Johnson at University of California, Berkeley in Berkeley, CA, and colleagues was titled, "Seasonal water storage, stress modulation, and California seismicity." view more
Credit: Image produced by Christopher Johnson, Berkeley Seismological Laboratory
项新的研究报告称，在加州，大规模的水的季节性周期变化造成了一定的小规模地震活动。这些记过揭示了雪、雨、雪水和迳流以及与农业有关的水变化是如何改变区域性断层应力的，在某些情况下它们会带来地震后果。在断层线上或附近的应力改变可引发地震活动。造成这些改变的原因可谓林林总总，其中包括流体孔隙压力的变化。在这里，Christopher Johnson和同事希望进一步地探索交替性潮湿与干旱周期对改变地应力并最终驱动地震中所扮演的角色。他们将2006-2014年中由GPS数据所估测的地应力的季节性变化与在这些年间加州的地震发生率进行了比较；他们发现，与水和雪的积累、雪融化、径流或农业灌溉相关的地应力的些微改变确实会影响地震发生的可能性。作者说，例如，在圣安德烈亚斯断层体系内，在干旱的夏季月份，地震情况更容易造成断层破裂。与此同时，沿着东加州剪切带断层至内华达山脉以东，地震更可能发生在潮湿的冬季月份。
###
Journal
Science