A second powerful earthquake shook Venezuela on Wednesday, striking just 39 seconds after the first quake subsided. The two earthquakes registered magnitudes of 7.1 and 7.5, causing significant concern among residents and seismologists alike.
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According to the U.S. Geological Survey, these two earthquakes are classified as a doublet array, which refers to the occurrence of two earthquakes with similar magnitudes that strike the same geographic area almost simultaneously.
Harold Tobin, director of the Pacific Northwest Seismic Network and a professor at the University of Washington, stated, “The first seismic wave had not yet dissipated when the second quake occurred.”
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It’s not unusual for two earthquakes to occur in rapid succession; however, this particular sequence of tremors led to extensive damage, with reports indicating at least 188 fatalities, over 1,520 injuries, and more than 150 individuals still unaccounted for.
According to Tobin, “The first quake likely compromised the structural integrity of several buildings. If they survived the initial earthquake, the subsequent quake could lead to their collapse.”
The Richter scale is logarithmic, indicating that a 7.5 magnitude earthquake releases approximately three times the energy of a 7.1 magnitude earthquake. Each integer on the scale represents a tenfold increase in amplitude.
This doublet earthquake pattern occurred in a complex fault system near San Felipe, Venezuela. The intricacies of this zone will likely prolong the researchers’ efforts to fully comprehend which faults were involved.
Maria Beatriz Magnani, a seismology professor at Southern Methodist University who studied Venezuela’s fault lines in the early 2000s, noted that the rupture transpired along the boundary of the South American and Caribbean tectonic plates, which are moving laterally past each other. The USGS estimates this eastward movement occurs at roughly 20 millimeters (approximately three-quarters of an inch) annually, compounded by compression forces as the plates interact.
Early assessments suggest that both earthquakes were of the strike-slip variety, characterized by one plate shifting past another. However, further data is still needed to clarify the mechanisms of these seismic events.
Magnani remarked, “It will take time to fully decipher the history of this fault. This is an exceedingly intricate plate boundary.”
Tobin indicated that the first earthquake likely instigated the second.
He stated, “This region is characterized by a complex arrangement of faults and fractures rather than a singular fault line, adding to the complexity of this earthquake sequence.”
A 1999 study in the Bulletin of Atmospheric Sciences reviewed 70 earthquakes over a year, finding that 22% of earthquakes greater than magnitude 7.5 were part of doublets. Venezuela had also experienced doublet earthquakes of magnitudes 6.2 and 6.3 in 2025, but they occurred southwest of Wednesday’s quake, resulting in one death and over 110 injuries according to the USGS.
In 2023, a pair of earthquakes measuring 7.8 and 7.5 struck southern Turkey and Syria, leading to over 3,000 fatalities.
In North America, two magnitude 6.2 earthquakes near the British Columbia-Alaska border were recorded within a two-hour window in May 2017, while a double earthquake in Klamath Falls, Oregon, featured a magnitude 5.9 tremor followed by a magnitude 6.0 event two hours later in September 1993.
Tobin noted that experts are still evaluating whether the events on Wednesday should be classified as a doublet, although the USGS currently characterizes them as such.
The classification remains a topic of debate among seismologists, creating discussions about whether this represents two separate earthquakes or one event with multiple stages.
Venezuela has recorded five earthquakes of magnitude 7.0 or greater since 1900, but none occurred along the fault line where Wednesday’s events transpired. This indicates that stress may have been building in this region for over 200 years.
Tobin added that no earthquake measuring 7.0 or higher has occurred along the fault since around 1812.
According to Magnani, the recent twin earthquakes will offer invaluable data for researchers aimed at uncovering fault structures concealed beneath the Earth’s surface.
“This event provides new insights into how the fault behaves and aids in comprehending the complexities of this region,” Magnani concluded. “Each earthquake and aftershock enriches our understanding of this intricate geological area.”
Source: www.nbcnews.com
