Item talk:Q58740

Field survey of earthquake effects from the magnitude 4.0 southern Maine earthquake of October 16, 2012

The magnitude 4.0 earthquake that occurred on October 16, 2012, near Hollis Center and Waterboro in southwestern Maine surprised and startled local residents but caused only minor damage. A two-person U.S. Geological Survey (USGS) team was sent to Maine to conduct an intensity survey and document the damage. The only damage we observed was the failure of a chimney and plaster cracks in two buildings in East and North Waterboro, 6 kilometers (km) west of the epicenter. We photographed the damage and interviewed residents to determine the intensity distribution in the epicentral area. The damage and shaking reports are consistent with a maximum Modified Mercalli Intensity (MMI) of 5–6 for an area 1–8 km west of the epicenter, slightly higher than the maximum Community Decimal Intensity (CDI) of 5 determined by the USGS “Did You Feel It?” Web site. The area of strong shaking in East Waterboro corresponds to updip rupture on a fault plane that dips steeply east. 

Table of Contents

• Abstract
• Introduction
• Historical Seismicity and Seismic Hazard in Maine
• Focal Mechanism, Centroid Depth, and Moment Magnitude
• Postearthquake Intensity Survey
• Building Damage
• Shaking Effects
• Comparing the Field Intensities to the “Did You Feel It?” Intensities
• Inferring the Fault Plane from the Intensity Distribution
• Conclusions
• References Cited