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Studies of Fragile Geologic Features in Central New England, USA, and Northeastern New Zealand

Description: 

We provide an overview of studies of fragile geological features (FGFs) in New England, USA, and New Zealand. The New England studies focus on FGFs in Massachusetts, New Hampshire, and western Maine. The FGFs are large erratic boulders that became delicately balanced during melting of the Laurentide ice sheet 21,000 to 15,000 years ago. Each FGF was photographed for development of a 3-dimensional model to quantify the fragility (shaking required to topple the FGF), and seismometers were briefly installed both on and away from the FGF to measure the response of the boulder to push tests and ambient noise. The age and fragility of the FGFs appear to show compatibility with the U.S. National Seismic Hazard Model (NSHM), likely due to the absence of large earthquakes (Mw>7) in the region since the FGF emplacement and short period motions from moderate earthquakes (5<Mw<7) being insufficient to topple the rocks. The New Zealand studies focus on FGFs in the east coast of the North Island, where the new NSHM shows major increases in hazard relative to earlier models. At the time of writing this abstract only reconnaissance efforts had been carried out, with studies of the fragility and age of specific FGFs planned for early 2024.

Session: Assessing Seismic Hazard for Critical Facilities and Infrastructure – Insights and Challenges - II

Type: Oral

Date: 5/3/2024

Presentation Time: 05:00 PM (local time)

Presenting Author: Mark

Student Presenter: No

Invited Presentation: 

Authors