Influence of the upper mantle structures on the New Madrid Seismic Zone

A high-resolution tomography study for the mantle beneath the New Madrid Seismic Zone (NMSZ), a major intraplate earthquake zone in the Central and Eastern US, reveals 3
- 5 % low Vp and Vs anomalies in the upper mantle in the depth range 100 to 250 km. When attributed only to temperature variations, such low velocities lead to high temperatures. We then compute differential stresses using three-dimensional numerical models subjected to a loading similar to the regional stresses. The model assume a Maxwell viscoelastic crust and mantle with viscosities based on the temperature converted from the tomography. We find that weaker upper mantle concentrates stress in the overlying brittle crust leading to earthquake generation. This work is supported by National Science Foundation (NSF - ICER) under award number 1639706.