We analyzed 16,150 transverse component seismic recordings from 54 deep‐focus earthquakes in the South American and Caribbean regions recorded at broadband stations in North America between 2005 and 2012. We treated subgroups of seismic stations within 3° radius geographical bins as seismic arrays and performed vespagram analysis. We focused on the S, ScS, and Scd arrivals and collected data in the epicentral distance range from 55° to 90°. In particular, we searched for D″ discontinuity presence in the vespagrams in a 25° by 35° (or 1520 by 2130 km) area beneath Central America. Analysis of these data showed 125 clear Scd observations, 180 Scd observations of lesser quality, and 343 nonobservations. We produced a new map of the discontinuity height beneath Central America. Our map shows an average discontinuity height of 286 ± 6 km (σ = 76 km). The region is punctuated by a large topographic high centered at approximately 10°N and 90°W with a maximum height of 380 km. Two smaller topographic highs are located at approximately 4°N and 81°W (discontinuity height of 320 km) and at 4°N and 70°W (height of 315 km). The observation of multiple Scd arrivals collocated with the strongest gradients in inferred topography provides evidence for topographic variation on the discontinuity rather than multiple discontinuities. The regions where the discontinuity has the greatest height can be explained by localized enrichment of mid‐ocean ridge basalt from the subducted Farallon slab impinging on the core‐mantle boundary.

We analyzed transverse and radial component recordings from the 2010 M6.3 southern Spain earthquake (depth = 620 km) recorded on 370 broadband stations in North America. We grouped these seismograms into subarrays and applied fourth root vespa processing (vespagram analysis) in order to enhance low‐amplitude arrivals. These vespagrams show clear Scd arrivals which indicate the existence of the D″ discontinuity beneath the North Atlantic Ocean (45–60°N, 45–55°W). These observations are best fit with a +2–4% velocity increase at the top of the D″ discontinuity at a height above the core‐mantle boundary of 304 ± 14 km. We do not observe Scd arrivals at the eastern end of our study region which is consistent with the presence of the easternmost edge of the ancient Farallon plate.

We propose a template-matching workflow capable of improving detection sensitivity of a seismic network and demonstrate its performance on the local seismic network comprising Texas Seismological Network installations in West Texas. We use three earthquakes from three clusters as our templates. Template matching is applied to each station independently. Then, SeisComP3 scanloc associator groups the obtained picks into seismic events following moveouts between stations consistent with a velocity model. In comparison to short-term over long-term average detection workflow, the number of “new,” previously undetected events more than doubles. The events detected by the template-matching workflow are registered on a set of stations, thus allowing for their absolute location. Template matching improves local network sensitivity. Among network parameters, station noise conditions appear to have the highest influence on the effectiveness of the workflow.

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