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Dynamic Rupture Modeling of the 1811-12 New Madrid Earthquakes

Session: Exploring Rupture Dynamics and Seismic Wave Propagation Along Complex Fault Systems II

Type: Oral

Date: 4/20/2021

Presentation Time: 10:30 AM Pacific

Description: 

The New Madrid seismic zone has produced damaging earthquakes in the past such as the infamous 1811-12 sequence. However, large magnitude earthquakes are infrequent in the New Madrid Seismic Zone and little is known about the rupture propagation process. Here we use three-dimensional dynamic rupture models to simulate the rupture propagation process during the large magnitude 1811-12 earthquakes. The three largest earthquake events in the 1811-12 sequence are likely to have occurred on major nearby or intersecting faults in the area: the Cottonwood Grove strike-slip fault, the northern new madrid strike-slip fault, and the Reelfoot thrust fault.

Variations in fault geometry become crucial when considering complex rupture propagation and fault interactions. For example, depending on fault geometry and prestress conditions, rupture can “jump” from one fault to nearby or intersecting fault segments generating larger magnitude events and significantly increasing hazard. Therefore, we introduce a fault geometry which contains two strike-slip faults linked by the Reelfoot thrust fault with variable strike. We use our fault geometry to run dynamic rupture models and investigate variations in rupture propagation due to nucleation location and different prestress conditions. We aim to understand how the major faults in the New Madrid seismic zone interact during events similar to those in 1811-12 and to gain insight to the maximum magnitude event. Our preliminary results suggest that for events nucleating on the Cottonwood Grove fault, the strike of the Reelfoot thrust plays a significant role in the partitioning of slip and state of stress north and south of the intersection.

Presenting Author: Erin Cunningham

Student Presenter: No

Authors