What is a doublet and how did it hit Venezuela?
Typically, when two quakes occur in quick succession, one is considered to be the main event and the other an aftershock. A doublet comprises two independent mainshocks of comparable magnitude, close in time and location.
A typical large earthquake appears on instruments as a sharp, sudden burst of energy. However, in Venezuela's case, scientists from the US Geological Survey studied the two quakes and saw long, low rumbles that jolted upward, as if two separate engines fired one after the other. This indicated that both were mainshocks. The first quake of 7.2-magnitude occurred on the Boconó branch of San Sebastián, a large fault line that runs along Venezuela’s northern coast. The initial rupture transferred stress from Boconó onto San Sebastián, which snapped, producing the 7.5-magnitude quake. However, whether this counts as one quake or two is a matter of scientific debate.
How rare is such a doublet?
Data compiled by Down To Earth from peer-reviewed studies suggests 37 such events above magnitude 6 have been recorded since 1907, roughly one every three years. At 39 seconds, Venezuela's doublet has the third-shortest interval recorded.
The analysis shows 21 of the 37 doublets occurred in the past 20 years. However, Judith Hubbard, professor of earth and atmospheric Sciences at Cornell University, US, says this is not a complete picture, as improved monitoring makes modern doublets easier to detect.
Can impacts be managed?
While early warning systems exist in Japan and the US, Venezuela has limited measures like phone-based alerts, says Hubbard. For people directly above the fault, tremors came at the same time as any alert.
This factsheet was originally published in the July 16-31, 2026 print edition of Down To Earth