A team from the U.S. Geological Survey (USGS) has commenced the installation of seismic sensors to capture data on aftershocks following the 4.8 magnitude earthquake that shook New Jersey on April 5, 2024. These sensors aim to gather crucial information about the origin, duration, and magnitude of aftershocks in the affected area.
Greg Tanner, an electronics technician from the USGS’s Albuquerque Seismological Laboratory, is part of the team responsible for deploying eight “aftershock kits” this week. These kits will work in tandem with seismic sensors deployed by partners from institutions such as the Lamont Doherty Earth Observatory at Columbia University, the Texas Seismological Network at the University of Texas at Austin, Rutgers University, and Yale University.
Aftershocks are smaller earthquakes that occur in the vicinity of a larger seismic event, persisting for days to years afterward. Since the April 5 earthquake, the USGS has recorded 50 aftershocks ranging from magnitude 1.3 to 3.8. Projections indicate a 12 percent chance of a magnitude 3 or greater aftershock in the coming week, with a one percent chance of a magnitude 4 or greater event.
While earthquakes are not frequent in this region, they are not entirely unexpected. USGS Research Geologist Jessica Thompson Jobe explained that although there are no active faults in the area, numerous older, inactive faults exist, formed millions of years ago. Under current tectonic stresses, these faults can intermittently reactivate.
Unlike seismic activity in the West, earthquakes in the Eastern U.S. are felt more intensely and over a wider area due to the characteristics of older rock formations. Oliver Boyd, a USGS Research Geophysicist, described how these older rocks, exposed to extreme pressures and temperatures over time, tend to be harder and denser. Faults in such rocks have also had more time to heal, facilitating the transmission of seismic waves.
The aftershock kits being deployed include sensors for recording strong motion and high frequency, as well as devices for transmitting digital data through the cellular network, all powered by solar panels. Data collected in real-time will be sent to the USGS’s National Earthquake Information Center in Golden, Colorado, for analysis.
Sarah McBride from the USGS Earthquake Hazards Program emphasized the importance of studying aftershocks to glean insights into earthquake behavior, aiding in better preparation for future seismic events.
