Stress development in heterogenetic lithosphere: Insights into earthquake processes in the New Madrid Seismic Zone

Yan Zhan, Guiting Hou, Timothy Kusky, Patricia Gregg

Research output: Contribution to journalArticlepeer-review

Abstract

The New Madrid Seismic Zone (NMSZ) in the Midwestern United States was the site of several major M 6.8-8 earthquakes in 1811-1812, and remains seismically active. Although this region has been investigated extensively, the ultimate controls on earthquake initiation and the duration of the seismicity remain unclear. In this study, we develop a finite element model for the Central United States to conduct a series of numerical experiments with the goal of determining the impact of heterogeneity in the upper crust, the lower crust, and the mantle on earthquake nucleation and rupture processes. Regional seismic tomography data (CITE) are utilized to infer the viscosity structure of the lithosphere which provide an important input to the numerical models. Results indicate that when differential stresses build in the Central United States, the stresses accumulating beneath the Reelfoot Rift in the NMSZ are highly concentrated, whereas the stresses below the geologically similar Midcontinent Rift System are comparatively low. The numerical observations coincide with the observed distribution of seismicity throughout the region. By comparing the numerical results with three reference models, we argue that an extensive mantle low velocity zone beneath the NMSZ produces differential stress localization in the layers above. Furthermore, the relatively strong crust in this region, exhibited by high seismic velocities, enables the elevated stress to extend to the base of the ancient rift system, reactivating fossil rifting faults and therefore triggering earthquakes. These results show that, if boundary displacements are significant, the NMSZ is able to localize tectonic stresses, which may be released when faults close to failure are triggered by external processes such as melting of the Laurentide ice sheet or rapid river incision.

Original languageEnglish (US)
Pages (from-to)56-62
Number of pages7
JournalTectonophysics
Volume671
DOIs
StatePublished - Mar 7 2016

Keywords

  • Heterogeneous lithosphere
  • Intraplate earthquakes
  • New Madrid Seismic Zone
  • Stress
  • Viscoelastic model

ASJC Scopus subject areas

  • Geophysics
  • Earth-Surface Processes

Fingerprint

Dive into the research topics of 'Stress development in heterogenetic lithosphere: Insights into earthquake processes in the New Madrid Seismic Zone'. Together they form a unique fingerprint.

Cite this