Seismic‐Hazard Map of Southeast Missouri and Likely Magnitude of the February 1812 New Madrid Earthquake

Abstract

The New Madrid seismic zone lies beneath the upper Mississippi Embayment, straddling the border between southeastern Missouri and northwestern Tennessee. In late 1811 and early 1812, it produced five earthquakes of magnitudes > 6:5, violently shaking the central and eastern United States (CEUS). Its magnitude and recurrence are of concern to today's central United States regions. By considering the effects of local geology, deterministic scenario maps (M w 7.3 and 7.7) were produced for ground motions intended to simulate the 7 February 1812 event (NM3), which was the largest felt. These maps include spatial estimates of peak ground acceleration and of 0.2 s and 1.0 s spectral acceleration (SA). Compared with the isoseismic map of modified Mercalli intensities (MMIs) in southeast Missouri, the MMIs converted from 0.2 s SA suggest that M w 7.7 is a plausible scenario for NM3. To better constrain its magnitude, other CEUS sites shaken during NM3 were also examined. Local site conditions were studied and evaluated before calculating the threshold magnitude for the reported MMIs. These results indicate that the magnitude of NM3 was at least M w 7.6, which validates our estimated size of M w 7.7 for southeastern Missouri.

Evaluation of geohazards in the Cape Girardeau area using LiDAR and GIS, Southeast Missouri, USA

“…The preponderance of crystalline limestone bedrock with interconnected fault patterns and much younger unconsolidated materials like wind-blown loess and alluvial cover leads to the susceptibility of the northwest quadrant. This area has 17 embankment dams that fall just below the jurisdiction of Missouri's dam safety statutes, so the state does not The liquefaction potential is moderate to high because of the high-water table and preponderance of cohesionless sands beneath a surficial layer of overbank silts that create a semi-confined aquifer at shallow depth (Chung and Rogers 2015). The region also exhibits evidence of lateral spread features triggered by the 1811-1812 earthquakes (Fig.…”

Evaluation of Geohazards in the Cape Girardeau area using LiDAR and GIS, Southeast Missouri, USA

“…The liquefaction potential is moderate to high because of the high-water table and preponderance of cohesionless sands beneath a sur cial layer of overbank silts that create a semi-con ned aquifer at shallow depth (Chung and Rogers 2015). The region also exhibits evidence of lateral spread features triggered by the 1811-1812 earthquakes (Figure 2).…”