Natural fault barrier averts major Sındırgı quake, says expert

BALIKESİR

A 6.1 magnitude earthquake that struck the western province of Balıkesir's Sındırgı district on Aug. 10 was contained by a natural underground barrier along the fault line, averting a larger disaster, explains a seismology expert.

Mustafa Şenkaya, associate professor at Bursa Uludağ University and head of its earthquake research laboratory, said the phenomenon explains why the tremor’s aftermath has been unusual, with frequent aftershocks continuing more than a month later.

“Western Anatolia rarely shows this type of structure,” Şenkaya explained. “The fault ran into a barrier system underground. As it could not break through, it has been releasing energy through thousands of aftershocks, some reaching magnitude 5.”

Since Aug. 10, researchers have recorded more than 9,000 tremors, including dozens stronger than magnitude 4.

In a typical scenario, aftershocks decline in both strength and frequency within weeks of a mainshock.

In Sındırgı, however, the barrier effect has slowed the release of energy, prolonging seismic activity.

Şenkaya explained that the Sındırgı fault system had enough accumulated strain to produce a 6.5-magnitude earthquake or stronger. But the underground structure, composed of resistant rock formations, acted as a stopper.

“Instead of one larger rupture, the fault has been forced to discharge its energy in smaller bursts,” he said. “That is why we continue to experience aftershocks above magnitude 4.”

He emphasized that while the ongoing tremors may unsettle residents, the mechanism is ultimately helping to reduce the risk of a single catastrophic quake.

The August earthquake damaged buildings, injured dozens and forced residents to stay outdoors as hundreds of aftershocks persisted. An elderly man died shortly after being pulled out alive from the debris of a collapsed building.

In the aftermath of the main earthquake, authorities have recently begun building resilient homes in both Sındırgı and the neighboring town of Bigadiç.