30 New advances in geological and geophysical research on the Appalachian orogen. (Posters)

We invite contributions that discuss new research on the Appalachian orogen. Submissions should include, but are not limited to, geological or geophysical studies or works comprising a combination of both methods.

Monday, 23 March 2026
1:30 PM - 5:30 PM
CCC, Ballroom C

Using a High-density Nodal Deployment to Measure Regional Seismic-wave Propagation Across the Laurentia-Appalachian Suture of Northwestern Massachusetts

Paper number: 30-4
Program: Technical Sessions
Time: 1:30 PM – 1:30 PM

Authors

Abstract

The New England Appalachians preserve a record of repeated crustal and lithospheric modification through Neoproterozoic rifting of Rodinia, multiple Paleozoic orogenies during terrane accretion that offset the Moho in southwestern New England and created basins and domes, and Mesozoic rifting during the breakup of Pangea. Regional temporary seismic deployments in New England (SEISConn, GENESIS) and ongoing monitoring (NEST) have provided detailed images of deeper crust and upper mantle structure, but their typical seismic station spacing (~10 - 20 km) limits resolution of the uppermost crust and the ability to directly connect mapped bedrock geology to subsurface seismic velocities. Here we present preliminary results from a new high-density deployment of 100 short-period 3-component nodal seismometers with spacing <500 meters along a 50 km transect in northwestern Massachusetts that crosses the Laurentia–Appalachian terrane boundary. During one month of recording, the array captured local earthquakes from central Massachusetts and northern New Jersey, providing bidirectional direct P and S arrivals across the transect. Using these events, we measure direct P and S wave arrival times and compute differential travel times between neighboring stations. These measurements are used to estimate P and S wave velocities and to map differential velocity variations at sub-kilometer scale, which can highlight where velocity gradients or discontinuities coincide with mapped faults, lithologic contacts, and the terrane boundary. By exploiting dense spacing the differential approach isolates lateral velocity structure within the crust and provides constraints on heterogeneity that is inaccessible to regional network geometries. Our initial results demonstrate that dense nodal arrays can recover both average and differential P and S wave velocity structure across the array, providing a direct link between surface geology and crustal seismic properties of Massachusetts.

Geological Society of America Abstracts with Programs. Vol. 58, No. 2

doi: 10.1130/abs/2026NE-411306

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