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Looking for the Possible Epicenters and Magnitudes of Strong Prehistoric Earthquakes Near Boston, Massachusetts

Description: 

This study examines evidence of widespread mass wasting that was found in the sediments of Walden Pond, Concord, Massachusetts and Sluice Pond, Lynn, Massachusetts deposited between 1380-1520 CE and shortly after 1386-1509 CE, respectively, along with 15 landslides in the sensitive glaciomarine deposits of the Presumpscot Formation in southern Maine, all of which took place between 1221-1454 CE. In addition, the sediments in Walden Pond show evidence of mass wasting between 1050-1320 CE but which is not seen in Sluice Pond or in Maine. The younger event horizons in Walden and Sluice Ponds and possibly the landslides in southern Maine are attributed to an earthquake ~1400 CE; whereas, the older anomalous layer in Walden Pond is attributed to an event ~1200 CE. We carried out a modeling analysis to find the range of possible locations and magnitudes of earthquakes that could have disturbed the sediments in the ponds and caused the landslides in Maine. For an earthquake ~1400 CE, the area of possible epicenters is in eastern Massachusetts or southeastern New Hampshire, with a possible magnitude range of 5.6≤Mw≤6.7 (±0.3 uncertainty) if the earthquake also caused the landslides in Maine and with a magnitude as small as Mw 4.7±0.3 with an epicenter in eastern Massachusetts if the earthquake did not cause the landslides in Maine. An earthquake ~1200 CE with Mw 4.7±0.3 or a little larger near or west of Walden Pond is most likely, although an earthquake as large as Mw 6.2±0.3 and an epicenter as far west of Walden Pond as Worcester, Massachusetts is possible. The results of this study suggest that the seismic hazard in eastern Massachusetts and southeastern New Hampshire might need reevaluation.

Session: Advancing Seismic Hazard and Risk Assessment through Multi-Disciplinary Approaches [Poster]

Type: Poster

Date: 4/15/2026

Presentation Time: 08:00 AM (local time)

Presenting Author: John E. Ebel

Student Presenter: No

Invited Presentation: 

Poster Number: 41

Authors