The LArge-n Seismic Survey in Oklahoma (LASSO) Experiment

In 2016, the U.S. Geological Survey deployed >1800 vertical-component nodal seismometers in Grant County, Oklahoma, to study induced seismic activity associated with production of the Mississippi limestone play. The LArgeâ€n Seismic Survey in Oklahoma (LASSO) array operated for approximately one month, covering a 25 km by 32 km region with a nominal station spacing of ∼400  mâ . Primary goals of the deployment were to detect microseismic events not captured by the sparser regional network stations and to provide nearly unaliased records of the seismic wavefield. A more complete record of earthquakes allows us to map the spatiotemporal evolution of induced event sequences and illuminates the structures on which the events occur. Dense records of the seismic wavefield also provide improved measurements of the earthquake source, including focal mechanisms and stress drops. Taken together, we can use these findings to glean insights into the processes that induce earthquakes. Here, we describe the array layout, features of the nodal sensors, data recording configurations, and the field deployment. We also provide examples of earthquake waveforms recorded by the array to illustrate data quality and initial observations. LASSO array data provide a significant resource for understanding the occurrence of earthquakes induced by wastewater disposal. ; © 2019 Seismological Society of America. Published Online 7 August 2019. Data and Resources: Data collected by the LArgeâ€n Seismic Survey in Oklahoma (LASSO) experiment described and presented here have been archived at the Incorporated Research Institutions for Seismology (IRIS) Data Management Center under network code 2A in PH5 format and can be accessed at http://ds.iris.edu/mda/2A/?starttime=2016-04-11T13:20:06&endtime=2016-05-24T15:41:19 (last accessed July 2019). The doi for the LASSO dataset is 10.7914/SN/2A_2016 (Dougherty et al., 2016).Earthquake catalog data from the Oklahoma Geological Survey ...