Investigation into Tewksbury Earthquake Provides Insights on Seismic Activity
On April 5, 2024, a magnitude 4.8 earthquake in Tewksbury, New Jersey, surprised millions, with peculiar shaking reports originating from as far as New York City despite minimal damage near the epicenter. Research into the rupture direction revealed that the earthquake’s shaking was funneled toward the northeast, while traditional faulting patterns were not present. This event prompted significant investigation into new fault behaviors and seismic hazards in the region.
The recent magnitude 4.8 earthquake in Tewksbury, New Jersey, has evoked considerable interest due to its unexpected intensity and the widespread reports of shaking across the East Coast. This earthquake, recorded on April 5, 2024, was the largest to be instrumentally documented in New Jersey since the year 1900. While people located as far as 40 miles away in New York City experienced significant shaking, the damage observed near the earthquake’s epicenter was surprisingly minimal. YoungHee Kim of Seoul National University and her colleague, Won-Young Kim from Columbia University, investigated the peculiar pattern of shaking reports following their visit to the epicenter merely hours after the event. The researchers anticipated visible damages such as fallen chimneys or cracked walls, yet they found no substantial property damage at the site. They noted, “We expected some property damage—chimneys knocked down, walls cracked or plaster fallen to the ground—but there were no obvious signs of property damage.” In contrast, the reactions from residents in New York City were significant, prompting over 180,000 reports about the shaking, as detailed by USGS seismologist, Oliver Boyd. The data indicated that the earthquake affected approximately 42 million people across regions from Virginia to Maine, with reports showing differences in shaking intensity based on location. Areas southwest of the epicenter described the shaking as “weak,” while those to the northeast reported “light to moderate” shaking. Given the earthquake’s magnitude, it would typically be expected to result in more intense shaking within a ten-kilometer radius of the epicenter. In their examination of the earthquake’s rupture, the researchers focused on the Lg waves, a type of seismic wave, to model the rupture direction. Their findings suggested that the earthquake’s rupture moved towards the east-northeast on an east-dipping fault plane, directing the shaking away from the epicenter and towards northeastern regions. This pattern deviated from the typical thrust faulting expected in earthquakes of this nature in northeastern U.S. While some minor damage was identified, such as cracks in drywall and fallen objects, the research indicated that the well-known Ramapo fault system likely did not play a role in this earthquake. The study hints at the potential for discovering new earthquake sources and re-evaluating how stress and strain are addressed in the eastern United States. The deployment of additional seismometers by the USGS will facilitate further research into aftershock mechanisms and general seismic responses in the region.
The April 5, 2024 earthquake in Tewksbury, New Jersey, with a recorded magnitude of 4.8, drew attention due to an unusual distribution of shaking reports and minimal damage near the epicenter. The event was significant as it represented the strongest instrumentally recorded earthquake in New Jersey in over a century. The contrasting experiences between residents closer to the epicenter and those further away, particularly in New York City, prompted researchers to investigate the characteristics of the earthquake, especially focusing on the rupture direction and its effect on seismic intensity.
The findings surrounding the Tewksbury earthquake illuminate nuances in earthquake mechanisms in the northeastern United States. Not only did researchers uncover an atypical rupture direction, resulting in varying experiences of shaking, but they also opened avenues for studying hidden faults and understanding how seismic activity might behave differently in this region. This research underscores the importance of revisiting established models of earthquake behavior to enhance the comprehension of seismic risks.
Original Source: phys.org
