Trio of small earthquakes in Berks County no cause for concern, geologist says

A Kutztown University professor says the fact that Berks County experienced three small earthquakes within one week is no cause for concern.

“It’s not concerning because the earthquakes were so low-energy,” Dr. Edward Simpson, a professor of geology and chairman of the school’s physical science department, said Monday. “We can get earthquakes a lot bigger around here. In the scale of energy, those are so low that no one worries about them.”

Berks residents are no strangers to feeling the earth shake under their feet.

The area has a long history with earthquakes, experiencing more than a dozen small but noticeable quakes over the past four decades. The most recent episodes came last week, with residents around Sinking Spring and Bernville hearing loud booms and feeling small temblors.

Tremors hit the Sinking Spring area on Nov. 7 and Friday. The first was a 1.7-magnitude quake and the second had a magnitude of 2.1. And a 1.5-magnitude quake was reported a few miles east-southeast of Bernville in Penn Township early Friday morning.

None of the quakes produced any reports of damage, but county emergency officials did get some calls about the noise they created.

Simpson said that having three quakes happen in such a short span doesn’t provide much insight into the future. It is not an obvious precursor to more tremors or a harbinger of a “big one” being on the way.

In some places where earthquakes are common, geologists have a lot of data that can help to predict patterns. In rare cases those areas might experience foreshocks, which are smaller quakes that happen before a larger one.

In Berks, there simply isn’t enough data available to know if a few little quakes mean anything. But Simpson didn’t seem to think there’s much evidence that the recent quakes are foreshocks.

“Whether there is activity on the way is a tough one because we don’t know what foreshock patterns exist around this area,” he said. “I’m not aware of any foreshock patterns. If those are foreshock patterns, we haven’t been able to define them at this point.”

In fact, Simpson said, the quakes could even be just the opposite. He said they could be remnants of the last big earthquake to hit the area.

“They could even be aftershocks from that 1994 quake, as the rocks continue to readjust themselves after they’ve been moved,” he said, referring to a 4.6-magnitude quake that hit Wyomissing Hills. “It is still a possibility.”

Why is Berks prone to earthquakes?

Well, the answer dates back some 199 million to 251 million years.

Simpson said this area has gone through four mountain-building phases dating back to the Triassic Period. All that geological tumult has left the rock buried beneath Berks filled with tons of small fault lines.

The faults vary in age and size, he said, which means there’s frequent readjusting and crumbling going on. That’s not uncommon, Simpson said, with somewhere around 130,000 tiny earthquakes happening around the world each day.