A series of strong earthquakes has struck different parts of the world within hours of each other, rattling communities from Northern California to Japan and Venezuela and prompting questions about whether the events could be connected.
On June 24, at 15:10 GMT, a 5.6 quake rattled Northern California. Hours later, at 22:04 GMT, Venezuela was hammered by a 7.2 foreshock, followed just 38 seconds later by a savage 7.5 mainshock. Barely 25 minutes after that, at 22:30 GMT, a 6.9 quake struck offshore Japan. Three separate tectonic blows, within hours.
The quakes that struck Venezuela’s northern Caribbean coast caused widespread damage and triggered tsunami warnings across the region, killing hundreds.
More casualties are feared as search-and-rescue operations are underway.
The following day, Acting President Delcy Rodriguez declared a national state of emergency, with the US Geological Survey (USGS) estimating a 42% chance that the final death toll could be very high.
In Japan, a magnitude 6.9 earthquake struck off the coast of Iwate, according to the Japan Meteorological Agency.
The quake occurred about 42 kilometres (26 miles) from the coastal city of Kuji, at a depth of 50 kilometres (31 miles).
In the US, seismic activity was also recorded when a rural area of Northern California experienced its strongest earthquake since 1940 on Wednesday morning.
The magnitude 5.6 quake was centred about 7 miles (12 kilometres) northwest of Willits, according to the USGS.
Related
“Statistical coincidence”
Experts say the close timing of the seismic events does not necessarily mean they are connected.
They concede that close timing of the earthquakes is striking, but not unusual given global seismic activity patterns.
Peter Stafford, a professor of engineering seismology at Imperial College London, said such events are expected to occur independently in different regions.
“California experiences 2-3 events like this every year, on average. Japan experiences an event like the recent one, on average, roughly once per year. These are both ballpark estimates. Rates in Venezuela are harder to constrain, but these large events occur far less frequently, more like once every 50-100 years…”
According to Prof Stafford, in each region, events like this have happened, are expected and are inevitable.
“The fact that they happen to have occurred in close temporal proximity is almost certainly just a statistical coincidence.”
Stafford said that the models for triggering events are usually based on concepts related to static or dynamic stress transfer, adding that the stress changes are very small when considering teleseismic distances relevant to California, Japan, and Venezuela.
