Matt Fagan, Staff writer, @fagan_nj
It had been
relatively quiet this year, until geologists recorded a 1.3 magnitude
quake last weekend in Morris Plains, and then a 1.0 magnitude quake
Saturday in Morristown.
Last weekend’s tremor was
reported by Columbia University’s Lamont-Doherty Observatory to the
Morris Plains Police Department, which issued an advisory to residents
on Monday morning.
Lamont-Doherty spokesman Kevin
Krajick said the quake was pinpointed to a shallow depth of 6 kilometers
just north of Grannis Avenue, between Mountain and Sun Valley ways,
about 500 feet southeast of Mountain way School.
Rutgers Newark geology professor talks about earthquakes in northern New Jersey. Matt Fagan/NorthJersey.com
“It
was a very small earthquake at a very shallow depth,” Krajick said.
“Most people would not feel an earthquake that small unless they were
absolutely right under it, if that.”
“To date (there)
were no reported injuries or damage related to the earthquake and no
Morris Plains residents reported any activity to this agency,” according
to Morris Plains police Chief Jason Kohn
On the other
hand, Butler Police Lt. Mike Moeller said his department received “a
bunch of calls about it, between 9:30 and 10:30 p.m.”
Saturday’s earthquake was so minor that Morristown police said they received no calls from residents
The 16 tremors recorded in 2016
were minor, generally 1 or 2 magnitude, often misinterpreted as
explosions, said Alexander Gates, geology professor at Rutgers
University Newark campus.
“A lot of people in Butler
felt them over the course of the last year, but a lot of them didn’t
know it was an earthquake,” Gates said.
Butler is the
borough, but also the name of the fault that sits at the end of aseries
of others belonging to the Ramapo Fault, Gates said.
“I’d be willing to bet
that you’d have to go all the way to Canada and all the way to South
Carolina before you’d get one that active,” Gates said of the area which
runs from the New York state line in the Ringwood and Mahwah area down
to Butler and central Passaic County, Gates said.
Of last year’s 16 earthquakes, 12 were directly associated with the faults around Butler, Gates said.
Butler
Councilman Ray Verdonik said area residents are well aware of the
frequency of earthquakes and agrees they are often difficult to discern.
During one earthquake, the councilman said he and his neighbors rushed from their homes.
“We thought it was from Picatinny Arsenal or a sonic boom.” he said.
Won-Young Kim,
director of the Lamont-Doherty Cooperative Seismographic Network,
which monitors earthquakes in the Northeast, said often very shallow,
the low magnitude quakes’ waves cause much ground motion. He said even
though the waves don’t travel very far, they can seem more intense than
the magnitude suggests.
They may not topple chimneys, he said but can crack foundations and frighten residents.
To
put earthquake magnitudes in perspective, experts said each year there
are about 900,000 earthquakes of 2.5 magnitude or less recorded annually
by seismograph. These mild tremors are usually not felt.
There are 30,000 that measure between 2.5 and 5.4, and these are often felt, but cause minor damage.
About
500 quakes worldwide are recorded between 5.5 and 6 magnitude per year
and cause slight damage to buildings and structures.
The 100 that fall within 6.1 and 6.9 may cause lots of damage in populated areas.
The 20 or so which fall within the 7 and 7.9 magnitude per year are considered major and cause serious damage.
Those that measure at 8 or greater can totally destroy communities near the epicenter and average one every five to 10 years.
The earthquake recorded in Mexico last week measured 7.1 magnitude.
Gates
said he has identified most of the region’s numerous faults, but has
yet to name them all. Among the unnamed include the faults responsible
for last year’s quakes in the region.
Plates are the masses of the earth’s
crust that slowly move, maybe as little as a few centimeters a year to
as much 18 centimeters, around the globe. Faults such as the San Andreas
are interplate and occur near where two plates meet.
The
plate North America rides upon runs from the Mid Atlantic Ridge to the
Pacific Coast. The theory is that as plates interact with one another,
they create stress within the plate. Faults occur where the crust is
weak, Gates said. Earthquakes relieve the built up pressure.
Boston
College Geophysics Professor John Ebel said he and a Virginia Tech
colleague, believe the seismically active areas in New York and South
Carolina are where some 200 million years ago, the plates tried to break
off but failed. This led to a weakening of the earth’s crust which
makes them susceptible to quakes.
While not
predictable, the data collected seem to suggest earthquakes occur
somewhat periodically, 40 active years followed by 40 less active, Gates
said.
“We are over due for a 3 or 4” magnitude, Gates said. “A 4 you’d feel. It would shake the area. Everybody would be upset.”
Ebel
does not fully agree. He said saying “overdue” might be somewhat
misleading. Earthquakes happen through a slow process of rising stress,
“like dropping individual grains of sand on the table.”
You never know which grain will cause the table to break, he said.
Still
all three experts say statistically it is only a matter time before a
magnitude 5 quake is recorded in the northern New Jersey area.
The
scientists said quakes in the Northeastern part of the United
States tend to come 100 years apart and the last one was recorded in
1884 believed to be centered south of Brooklyn. It toppled chimneys and
moved houses from their foundations across the city and as far as
Rahway.
Washington D.C. experienced a 5.8 magnitude
quake in 2011, which was felt in the Northeast, Gates said.
That quake cracked the Washington Monument.
A similar quake was recorded in 1737 in Weehawken, Gates noted.
“Imagine
putting a 5.5 magnitude earthquake in Weehawken, New Jersey next to the
Bridge, next to the tunnel,” Gates said. “Boy that would be a dangerous
one.”
In 2008 Columbia University’s The Earth
Institute posted an article titled: “Earthquakes May Endanger New York
More Than Thought, Says Study.”
“Today, with so many
more buildings and people, a magnitude 5 centered below the city would
be extremely attention-getting,” the article’s co-author John Armbruster
wrote. “We’d see billions in damage, with some brick buildings
falling.”
The threat though, is not tangible to many, Armbruster wrote.
“There
is no one now alive to remember that last one, so people tend to
forget. And having only a partial 300-year history, we may not have seen
everything we could see. There could be surprises — things bigger than
we have ever seen,” Armbruster wrote.
The Earth Institute’s article did note New York City added earthquake-resistant building codes in 1995.
New
Jersey also began to require earthquake-resistant standards in the
1990s. The state, following the 2011 Virginia quake, now requires lake
communities to make dams able to withstand a magnitude 5 earthquake.
The
issue, Gates said, is that many of the buildings were built before
these codes went into effect. A “sizable” earthquake could cause much
damage.
Then there’s the prediction that every 3,400 years this area can expect a quake at 7 magnitude.
According
to the Earth Institute article, a 2001 analysis for Bergen
County estimates a magnitude 7 quake would destroy 14,000 buildings and
damage 180,000 in that area alone. Likewise, in New York City the
damage could easily hit hundreds of billions of dollars.
Ebel
noted that depending on the depth and power of a severe quake, damage
could be also be wide ranging. In 2011, Washington D.C., 90 miles away
from the epicenter, which was located in central Virginia, suffered
significant damage. Cities like Philadelphia fall within that radius.
“The
big one could happen tomorrow or 100 years from now. That’s the
problem,” Gates said. It geological terms 100 years is just a spit in
the ocean, he noted.
Then again North Jersey is more likely to be hit by hurricane in the next three years, Gates added.
Email: Fagan@NorthJersey.com
Staff Writer William Westhoven contributed to this report.
New Jersey’s top earthquakes
• Dec. 19, 1737 — Weehawken, believed to be a 5-plus magnitude quake, could be very serious if occurred in same spot today.
•
Nov. 29, 1783 — Western New Jersey. Geologists are not exactly sure
where it happened because area was sparsely populated. Estimated
magnitude varies from 4.8 to 5.3. Felt from Pennsylvania to New England.
•
Aug. 10, 1884 — A 5.2 earthquake occurred somewhere near Jamaica Bay
near Brooklyn. The quake toppled chimneys and moved houses off their
foundations as far Rahway.
• The biggest earthquake in
the last 45 years of data available form USGS was a 3.8 quake centered
in Carneys Point in Salem County on the morning of Feb.28, 1973
• New Jersey has never recorded a fatality due to an earthquake, according to the DEP.