English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Zendy Plus

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Zendy Tools

Zendy Open

The Newberry volcano geothermal site was stimulated to induce hydroshearing during 2012 and 2014. Aguiar and Myers (2018) relocated microseismic events for both stimulations by first using a data mining approach initially designed for webpages, Google’s PageRank, to identify event clusters. They later relocated all possible events within these clusters by using a version of the Bayesloc approach (Myers et al., 2007) that incorporates differential arrival time data. The focus of this study is estimation of focal mechanisms for events in the 2014 relocated data set using first motion polarities of P-waves and S-waves, using the method of Shelly et al. (2016). We first manually pick P-wave and S-wave polarities for the reference event in each cluster, then use waveform cross-correlation to determine whether recordings of other events are the same or reversed polarity. We find that most events within each cluster have consistent polarities relative to the reference event, confirming the conclusion of Aguiar and Myers (2018) that events within a cluster have similar mechanisms. We also compute S/P amplitude ratios for these small events using the method of Hardebeck and Shearer (2003), and compute the mechanisms using HASH (Hardebech and Shearer, 2002), which is an open software package from the USGS that uses first motion polarities and amplitude ratios to find the best-fitting, double-couple mechanism for each event. Again, we find similar focal mechanisms within each cluster and two predominant focal mechanisms for the whole sequence. The deeper clusters have normal-fault mechanisms, whereas the shallower events, close to the top of the open hole section of the borehole, are strike-slip with east-west motion.

Microseismic Focal Mechanisms and Implications for Changes in Stress during the 2014 Newberry EGS Stimulation