气候变化领域集成服务门户(CCPortal): Hydrospheric modulation of stress and seismicity on shallow faults in southern Alaska

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DOI	10.1016/j.epsl.2019.115904
	Hydrospheric modulation of stress and seismicity on shallow faults in southern Alaska
	Johnson C.W.; Fu Y.; Bürgmann R.
发表日期	2020
ISSN	0012821X
卷号	530
英文摘要	Shallow (≤40 km), low magnitude (M≥2.0) seismicity in southern Alaska is examined for seasonal variations during the annual hydrological cycle. The seismicity is declustered with a spatio-temporal epidemic type aftershock sequence model. The removal of aftershock sequences allows detailed investigation of seismicity rate changes as water, snow and ice loads modulate crustal stresses throughout the year. The GRACE surface loads are obtained from the JPL global land and ocean mass concentration blocks (mascon) solutions. The stress changes at a depth of 10 km are calculated using a 1D spherical layered Earth model. To evaluate the induced seasonal stresses of ∼10 kPa, we use >30 yr of earthquake focal mechanisms to constrain the tectonic background stress field orientation and assess the seasonal stress change with respect to the principal stress orientations. The background stress field is assumed to control the preferred orientation of faulting, and stress perturbations are expected to increase or decrease seismic activity on the faults. The number of excess earthquakes is calculated with respect to the background seismicity rates for discrete stress intervals. The results indicate a ∼25% increase in regional seismicity rates that correlate with a ∼3-month time lag following failure-encouraging annual mean-normal-stress, differential stress, and least principal compressive stress. No immediate earthquake rate variations are observed in this region-wide analysis. The correlation with a 3-month time lag suggests increased mobility of preexisting fluids at seismogenic depths is varying the pore pressure within fault zones to modulate the seismicity rates throughout the seasonal loading cycle. © 2019 Elsevier B.V.
关键词	crustal seismicity GRACE hydrospheric loading seasonal stress modulation
英文关键词	Compressive stress; Faulting; Hydrosphere; Modulation; Snow and ice removal; crustal seismicity; Earthquake focal mechanisms; Epidemic-type aftershock sequences; GRACE; Preferred orientations; Stress modulation; Stress perturbations; Stress-field orientation; Earthquakes; crustal structure; fault zone; focal mechanism; GRACE; hydrosphere; pore pressure; seismicity; spatiotemporal analysis; stress field; Alaska; United States
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/202682
作者单位	Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093, United States; School of Earth, Environment and Society, Bowling Green State University, Bowling Green, OH 43403, United States; Berkeley Seismological Laboratory, University of California Berkeley, Berkeley, CA 94720, United States
推荐引用方式 GB/T 7714	Johnson C.W.,Fu Y.,Bürgmann R.. Hydrospheric modulation of stress and seismicity on shallow faults in southern Alaska[J],2020,530.
APA	Johnson C.W.,Fu Y.,&Bürgmann R..(2020).Hydrospheric modulation of stress and seismicity on shallow faults in southern Alaska.Earth and Planetary Science Letters,530.
MLA	Johnson C.W.,et al."Hydrospheric modulation of stress and seismicity on shallow faults in southern Alaska".Earth and Planetary Science Letters 530(2020).