The rare twin earthquakes that struck Venezuela within just 40 seconds of each other were not equal in power. Although the two shocks measured magnitude 7.2 and 7.5, the second earthquake released nearly three times more energy than the first, highlighting how even a small increase on the earthquake magnitude scale translates into a dramatic jump in destructive potential.
According to Professor R. Pradeep Kumar, Director of the CSIR-Central Building Research Institute (CBRI), the back-to-back tremors can clearly be classified as a double earthquake, also known as a seismic doublet.
“The first earthquake occurred with a magnitude of 7.2, and around 40 seconds later the second earthquake of magnitude 7.5 struck. We can clearly observe that the 7.5-magnitude earthquake released almost three times more energy than the 7.2-magnitude event,” Prof. Kumar explained.
At first glancethe difference between a magnitude 7.2 and 7.5 earthquake may appear small. However, earthquake magnitudes are measured on a logarithmic scale, meaning each increase in magnitude represents a substantial rise in energy release.
Scientists estimate that a one-unit increase in magnitude corresponds to roughly 32 times more energy. Since the Venezuelan earthquakes differed by 0.3 magnitude units, the second quake released approximately 2.8 to 3 times the seismic energy of the first.
“The magnitude scale is deceptive because it is logarithmic. A small increase in the number can represent a much larger increase in energy,” Prof. Kumar said.
The two powerful earthquakes struck northern Venezuela, triggering strong shaking across the country and parts of the Caribbean. The second, stronger quake significantly amplified the seismic hazard as buildings and infrastructure that had already been weakened by the first tremor were subjected to another intense burst of ground motion within less than a minute.
Experts say this is one reason why seismic doublets can be particularly dangerous. Unlike a typical mainshock followed by smaller aftershocks, both earthquakes in a doublet are independently large enough to cause damage, leaving little or no time for emergency response between them.
To help explain the enormous amount of energy involved, Prof. Kumar compared earthquake energy with that of nuclear explosions.
“To generate an earthquake of this scale, you are talking about energy equivalent to around 400 Hiroshima bombs,” he said, stressing that the comparison is intended only to illustrate the immense energy released and not to suggest any similarity in the way earthquakes and nuclear explosions occur.
While the Hiroshima comparison offers perspective, seismologists caution that earthquakes release energy over long fault ruptures deep beneath Earth’s surface, whereas nuclear explosions release energy almost instantaneously from a single point. The physics and impacts are fundamentally different.
Scientists continue to monitor aftershocks and study the rare Venezuelan seismic doublet to better understand how stress was transferred along the fault system. The event is expected to provide valuable insights into earthquake interactions and seismic hazards in the Caribbean region.
– Ends
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