Crustal structure of the mid-atlantic U.s. from P-wave receiver functions

Open Access
Author:
Arroyo, Gabriella B
Graduate Program:
Geosciences
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
August 10, 2015
Committee Members:
  • Andrew Arnold Nyblade, Thesis Advisor
Keywords:
  • crustal structure
  • receiver functions
  • Pennsylvania
  • Ohio
  • Appalachian
  • Scranton
  • Scranton High
  • Grenville Front
  • Allegheny Front
  • Mid-Continent rift
  • Vp/Vs
  • Hk stacking
  • PASEIS
  • UsArray
  • US Transportable
  • mid-atlantic
Abstract:
Crustal structure across the Mid-Atlantic portion of the U.S. has been investigated by modeling receiver functions. Estimates for Moho depth and Vp/Vs ratio have been obtained for 118 broadband seismic stations, centered around the state of Pennsylvania. The deployment of two temporary seismic networks starting in late 2012, the US Transportable Array and the Pennsylvania Seismic Network, has led to the highest seismic spatial coverage in this area of the U.S. to date. Crustal properties are determined using the H-k stacking method of receiver functions of Zhu and Kanamori [2000]. Average crustal thickness for the region is 44 km with a standard deviation of 5 km. A trend of crustal thinning occurs from west to east toward the coast, a result of the rifting of Pangea and the formation of the Atlantic Ocean in the Mesozoic. Crust up to 56 km thick is observed along the Grenville front in central Ohio, indicative of Proterozoic suture thickening, and is associated with a Bouguer gravity low-high anomaly along the suture. Another area of thickened crust is found in northwest Pennsylvania, possibly the result of post-Grenvillian collisional deformation. An area of thinner crust (36-40 km thick) is found in northeastern Pennsylvania along the Pennsylvania Salient. This region is associated with a +60 mGal Bouguer gravity anomaly, known as the Scranton High, and is interpreted to be a remnant Neoproterozoic rift. The thinner crust in this region indicates that the gravity high can be attributed to crustal thinning. Lastly the relationship between elevation and crustal thickness can be explained to a first order by an Airy isostatic model, but crustal thicknesses are much larger than necessary for Airy isostasy. Vp/Vs ratios in this area average 1.78, with a standard deviation of 0.05.