Thu, 19 Jul 2012 21:14 CDT
New Jersey - Loud and unexplained "booms" heard in one part of town several times this week were small and shallow earthquakes, according to a seismologist with the Lamont-Doherty Earth Observatory of Columbia University.Police were inundated with calls Monday night from residents who reported hearing and feeling three loud booms in succession starting at around 10 p.m., according to Chief of Police Douglas Scheer, who investigated the reports and contacted numerous agencies in a quest to explain what had happened.
"They were enough to jar residents in their homes and cause them to come outside," Scheer said. "We believed at the time it could have been some sort of explosion but as we spoke to more and more residents we determined it had to have come from underground."
The booms were all felt in a half square mile area centered around Rockaway, Franklin and Lincoln avenues in the borough, Scheer said.
"They caused homes to shake and people to become very nervous," Scheer said. "We had calls from people thinking people were breaking into their homes or something was blowing up."
Eric Nordmann, who lives on Rockaway Avenue, said the "events/episodes" sounded like an underground explosion.
"My entire house shook for a very brief time, but not just my house many houses on my street," Nordmann said.
Scheer said police received more than 20 calls and launched an investigation that included checking for possible explosions at Picatinny Arsenal and at a quarry in Rockaway Twp. Scheer said his office also checked to see if a transformer could have exploded or if the noises were a sonic boom.
The morning after the booms, officers also checked with businesses in the area to see if they might know what had happened.
"We (also) reached out to the Morris County Office of Emergency Management, the state Office of Emergency Management, the USGS (United States Geological Survey) and no one else reported anything," Scheer said.
The USGS referred them to the Lamont-Doherty Cooperative Seismographic Network and New Jersey Geological Survey but nothing had been reported to either of those organizations at that point.
The same type of noise was heard again on Wednesday at 2 a.m. and then again at 4 a.m. in the same general area, Scheer said.
"It was enough to make residents feel they needed to check things out and it was felt at the police department," Scheer said. "We called all the same people again and they did not have answers."
Yon-Young Kim, a seismologist with Lamont-Doherty, said equipment at seismic stations is designed to automatically let seismologists know when an earthquake with a magnitude greater than 2.0 has occurred.
The earthquakes that struck Rockaway were about 1.1 so it would not be immediately apparent that one had occurred, Kim said. After receiving several reports about it, Kim went and looked at the data Thursday evening.
"We are still working on it but there were three small earthquakes (on Monday)," Kim said. "The largest one was 1.1. which is very small."
Kim also found evidence of another quake at 1:58 a.m. on Wednesday and was checking out the possibility that there was a second that morning, at 4 a.m.
The quakes were shallow, meaning they occurred a mile or less underground, and this type of quake is often loud, according to Kim, who added that only people very close to the epicenter would hear and feel it.
"Usually you don't feel a 1.1 when its deeper," Kim said.