16-54 New Investigations of Seismicity in Moodus, Connecticut Using a Dense Array of Raspberry Shake Seismometers

Session: From Thin Section to Outcrop: Exploration of Undergraduate Research (Posters)

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Abstract:

The town of Moodus, Connecticut, is well known for its frequent low-magnitude seismicity, unusual in a passive continental margin setting. The Moodus area hosted the largest known earthquake in Connecticut history in the year 1791, likely of magnitude ~4.5. In the 1980s, there were four distinct earthquake swarms, each of which included at least one event with a magnitude of 2.0 or greater. Previous work located the earthquake hypocenters for these swarm events, all of which lie within a compact area of about a square kilometer. The region has experienced ongoing, low-magnitude seismicity over the past several decades, including a magnitude 2.3 earthquake in November 2024, a magnitude 1.8 in January 2025, and a magnitude 1.9 in January 2026. Moodus earthquakes are often heard rather than (or in addition to) being felt; the name Moodus comes from an indigenous word meaning “the place of noises.”

Beginning in October 2024, Yale University partnered with the East Haddam Historical Society to install a network of low-cost Raspberry Shake seismometers. We have installed a mix of three-component sensors, vertical component sensors, and one infrasound sensor in a dense array in and around the village of Moodus. The first two stations were installed in 2024, with an additional four installed in December 2025, and the remaining two slated for installation in 2026. We obtained good recordings of the January 7, 2026, earthquake on our network, enabling refined estimates of its location and depth. A major goal of our study is to apply a template matching approach to data recorded on our Raspberry Shakes, using the signals of known Moodus earthquakes to search for additional low-magnitude events that are not large enough to be included in the National Earthquake Information Center (NEIC) catalog. Our study is also a proof of concept for low-cost, ultra-dense monitoring networks in regions with low-magnitude seismicity, particularly in settings away from plate boundaries. Finally, we hope to contribute to our knowledge of the causative fault(s) for the Moodus earthquakes and to relate insights into fault geometry at depth with the regional geology of this part of the New England Appalachians.

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