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The New Madrid Seismic Zone: not dead yet.
1U.S. Geological Survey, Pasadena, CA, USA.
Science (New York, N.Y.)
|January 25, 2014
Summary
Ongoing New Madrid seismicity is not solely aftershocks from the 1811-1812 earthquakes. Instead, current seismic activity is driven by ongoing strain accumulation, not decaying aftershock sequences.
Area of Science:
- Geophysics
- Seismology
- Tectonics
Background:
- Investigating the source of intraplate seismicity is crucial for seismic hazard assessment.
- The New Madrid seismic zone (NMSZ) in the central U.S. experiences significant seismic activity, raising questions about its origin.
Observation:
- Historical and instrumental seismicity data from the NMSZ were analyzed.
- The study assessed whether current earthquakes are predominantly aftershocks of the 1811-1812 seismic sequence.
Findings:
- Synthetic earthquake sequences consistent with aftershock activity overpredict the number of large (magnitude ≥ 6) events observed in the past 200 years.
- The NMSZ's modern seismic activity cannot be explained solely by aftershocks from the 1811-1812 sequence.
Implications:
- Ongoing strain accumulation, rather than decaying aftershock processes, drives current seismicity in the NMSZ.
- Despite low deformation rates, seismic activity in the NMSZ is not diminishing over time, indicating persistent tectonic processes.
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