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- Title
Variations in Seismogenic Thickness Along the Central Alpine Fault, New Zealand, Revealed by a Decade's Relocated Microseismicity.
- Authors
Michailos, Konstantinos; Smith, Euan G.C.; Chamberlain, Calum J.; Savage, Martha K.; Townend, John
- Abstract
The Alpine Fault is an oblique strike‐slip fault that is known to fail in large magnitude (M7–8) earthquakes, yet it is currently seismically quiescent. We examine the low‐magnitude earthquake activity occurring along the central portion of the Alpine Fault using seismic data from five temporary seismic networks deployed for various lengths of time between late 2008 and early 2017. Starting from continuous seismic data, we detect earthquake arrivals and construct the longest and most extensive microearthquake catalog for the central Alpine Fault region to date, containing 9,111 earthquakes. This enables us to study the distribution and characteristics of the seismicity in unprecedented detail. Earthquake locations are constrained by high‐quality automatic and manual picks, and we perform relocations using waveform cross‐correlation to better constrain hypocenters. We have derived a new local magnitude scale calibrated by Mw values. Magnitudes range between ML−1.2 and 4.6, and our catalog is complete above ML 1.1. Earthquakes mainly occur southeast of the Alpine Fault (in the hanging wall) and exhibit low magnitudes. We observe a lack of seismicity beneath Aoraki/Mount Cook, which we associate with high uplift rates and high heat flow. Seismogenic cutoff depths vary along the strike of the Alpine Fault from 8 km, beneath the highest topography, to 20 km in the adjacent areas. Key Points: We determine an almost decade‐long, relocated earthquake catalog covering the central Alpine Fault, New ZealandSeismogenic cutoff depths vary along the strike of the Alpine FaultAnomalously shallow seismicity beneath Aoraki/Mount Cook coincides with the highest uplift rates
- Subjects
ALPINE Fault (N.Z.); EARTHQUAKE zones; INDUCED seismicity; SEISMOMETRY; HEAT equation
- Publication
Geochemistry, Geophysics, Geosystems: G3, 2019, Vol 20, Issue 1, p470
- ISSN
1525-2027
- Publication type
Article
- DOI
10.1029/2018GC007743