Examining the Tewksbury Earthquake: Insights into East Coast Seismicity and Shaking Reports
The April 5, 2024, Tewksbury earthquake (magnitude 4.8) surprised many across the East Coast, with reports of strong shaking in New York City despite minimal damage near the epicenter. Researchers analyzed the rupture’s direction to explain the unusual shaking patterns and found that the seismic event’s mechanics indicated a combination of thrust and strike-slip movements along an unmapped fault.
On April 5, 2024, a magnitude 4.8 earthquake occurred in Tewksbury, New Jersey, marking the largest seismic event in the state since 1900. Despite its strength, minimal damage was observed near the epicenter, while notable shaking was reported as far away as New York City, approximately 40 miles distant. Researchers YoungHee Kim from Seoul National University and Won-Young Kim of Lamont-Doherty Earth Observatory have conducted a detailed study published in The Seismic Record that seeks to elucidate this unusual phenomenon. They hypothesize that the earthquake’s rupture direction may have influenced the distribution of shaking perceived by residents. Upon examining the epicenter shortly after the event, the researchers noted an unexpected lack of property damage, contrasting sharply with the widespread reports from those in the New York City region, where residents described experiencing strong shaking. The United States Geological Survey (USGS) reported over 180,000 individual accounts of the earthquake’s tremors, indicating that approximately 42 million people felt the quake across a vast area stretching from Virginia to Maine. The analysis conducted by Kim and her colleagues indicated that the earthquake’s rupture traveled toward the east-northeast, potentially directing intense shaking away from the epicenter. This observation aligns with the understanding that earthquakes in the northeastern United States typically involve thrust faulting along pre-existing faults. However, the Tewksbury earthquake appeared to result from both thrust and strike-slip mechanisms along a previously unmapped fault plane. Additionally, while some minor structural damage was recorded, such as cracked drywall and fallen objects, no significant damage was reported at the epicenter. Notably, the investigation revealed that the well-known Ramapo fault system did not appear to be active during this seismic event, suggesting the presence of new earthquake sources in the region. The deployment of seismometers by the USGS will allow for further study of the aftershock sequence and how the crust responds to this significant mainshock. Such investigations can facilitate a better understanding of seismic hazards in the eastern United States and improve predictive models regarding the intensity and frequency of future seismic events.
Earthquakes in the northeastern United States are relatively rare compared to other regions such as California. The Tewksbury quake, occurring in 2024, is significant not only for its magnitude but also because it unexpectedly impacted areas far from its epicenter while leaving the epicenter with minimal damage. Understanding the mechanics of the rupture and the geological context is vital for improving earthquake preparedness and response.
The investigation into the 2024 Tewksbury earthquake reveals critical insights about the propagation of seismic waves and the unique geological factors at play, which resulted in unexpected shaking experiences miles away from the epicenter. Further studies utilizing the newly deployed seismometers promise to enhance the understanding of tectonic dynamics in the northeastern United States, potentially leading to better risk assessments and preparedness strategies for future seismic activity.
Original Source: phys.org
