Microearthquake evidence for reaction-driven cracking within the Trans-Atlantic Geotraverse active hydrothermal deposit
MetadataShow full item record
We detected 32,078 very small, local microearthquakes (average ML = −1) during a 9 month deployment of five ocean bottom seismometers on the periphery of the Trans-Atlantic Geotraverse active mound. Seismicity rates were constant without any main shock-aftershock behavior at ~243 events per day at the beginning of the experiment, 128 events per day after an instrument failed, and 97 events per day at the end of the experiment when whale calls increased background noise levels. The microearthquake seismograms are characterized by durations of <1 s and most have single-phase P wave arrivals (i.e., no S arrivals). We accurately located 6207 of the earthquakes, with hypocenters clustered within a narrow depth interval from ~50 to 125 m below seafloor on the south and west flanks of the deposit. We model the microearthquakes as reaction-driven fracturing events caused by anhydrite deposition in the secondary circulation system of the hydrothermal mound and show that under reasonable modeling assumptions an average event represents a volume increase of 31–58 cm3, yielding an annual (seismogenic) anhydrite deposition rate of 27–51 m3.
Author Posting. © American Geophysical Union, 2014. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Solid Earth 119 (2014): 822–839, doi:10.1002/2013JB010110.
Showing items related by title, author, creator and subject.
Detailed studies of the structure, tectonics, near bottom magnetic anomalies and microearthquake seismicity of the Mid-Atlantic Ridge near 37°N Macdonald, Ken C. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1975-09)The Mid-Atlantic Ridge is one of the most well known and yet poorly understood spreading centers in the world. A detailed investigation of the Mid-Atlantic Ridge crest near 37°N (FAMOUS) was conducted using a deeply towed ...
Microearthquake patterns following the 1998 eruption of Axial Volcano, Juan de Fuca Ridge : mechanical relaxation and thermal strain Sohn, Robert A.; Barclay, Andrew H.; Webb, Spahr C. (American Geophysical Union, 2004-01-14)Ocean bottom seismic networks deployed following the 1998 eruption of Axial seamount reveal an evolving pattern of microearthquake activity associated with subsurface magmatism and thermal strain. Seismicity rates decay ...
The tectonics and three-dimensional structure of spreading centers : microearthquake studies and tomographic inversions Toomey, Douglas R. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1987-09)Two-thirds of the Earth's surface has been formed along a global system of spreading centers that are presently manifested in several different structural forms, including the classic rift valley of the Mid-Atlantic ...