My First Earthquake

[Cracked Globe]

Saturday April 20, 2002 - 6:52 am

USGS Description

Update: The following is a release by the United States Geological Survey, National Earthquake Information Center: A moderate earthquake occurred about 15 miles southwest of Plattsburgh, New York at 4:50 AM MDT, Apr 20, 2002 (6:50 AM EDT in New York). The magnitude and location may be revised when additional data and further analysis results are available. The earthquake was felt from Cleveland, Ohio to Maine and Baltimore, Maryland. A bridge was damaged at Jay, there was road damage at Keeseville and a chimney was damaged at Lake Placid. This earthquake was about the same size as the Blue Mountain Lake earthquake on October 7, 1983.

Tectonic Setting This earthquake occurred in the northeastern part of New York State, an area that experiences moderate-sized but infrequent seismic activity. Although earthquakes occur on geologic faults, in the northeastern U.S. it is difficult to assign an earthquake to a particular fault because they rarely cause surface rupture. The most recent nearby earthquake of note occurred 80 km to the southwest, a magnitude 5.1 event in 1983. The largest historic earthquake in the northeastern region of the U.S. and nearby parts of Canada had an estimated magnitude of 7. It occurred near Charlevoix, Quebec in 1663, 425 km to the northeast of this latest event. The pattern of historic seismicity can be seen in the USGS publication, "Earthquakes in and near the Northeastern United States, 1638 -1998."

Quake information

Quake map

E-mail to my kids shortly after:

Guess what? We had an earthquake here this morning. I'm so excited! I felt it. I was sitting at the computer, it was 6:52 am and I felt movement. I turned around because I thought Mom was walking into the den behind me. She wasn't there. The whole house was shaking! It lasted for about 3 - 5 seconds. The pull chain on the desk lamp was swaying back and forth. It was a little scary. About 10 minutes later, they were announcing the earthquake on Channel 16. They didn't figure out exactly where it was centered yet, but they said it was felt in Williamsport to Allentown to Wayne County.

Follow-up e-mail to my kids:

They just announced on Channel 16 that the earthquake was a 5.1 quake with the epicenter in near Plattsburg, NY. That's near Lake Champlain.

From ABC (edited):

5.1 Earthquake Rattles Northeast

Earthquake of 5.1 Magnitude Rattles Northeast, Felt From Maine to Maryland

N E W Y O R K, April 20 An earthquake felt from Maine to Maryland rattled the Northeast on Saturday morning with a magnitude of 5.1, according to the U.S. Geological Survey.

The earthquake hit just before 7 a.m. about 15 miles southwest of Plattsburgh, in northern New York near the Vermont and Canadian borders.

There were no immediate reports of injuries, but the Vermont State Police received calls about cracked foundations and broken windows, and sections of at least two roads collapsed near the epicenter in upstate New York.

The earthquake was recorded at 6:50 a.m., said William Ott, a seismologist at Weston Observatory at Boston College.

He said the quake was "moderate." A typical 5.1 earthquake would cause cracked plaster, broken windows and minor structural damage around the epicenter, he said.

"There are faults all over the northeastern United States," Ott said. "They're not as active as the ones in California, but they're capable of producing earthquakes of this size from time to time."

The largest earthquake recorded in New York, according to the USGS, was a 5.8 magnitude quake in 1944 that was centered in Massena, about 3 miles from the Canadian border.

Won Young Kim, a seismologist with Columbia University's Lamont Doherty Earth Observatory, said there was a magnitude 5.2 quake in 1993, about 50 miles south of Saturday's epicenter. He said a magnitude 3.5 quake occurred just south of Plattsburgh on April 20, 2000.

Reports of the shaking Saturday came from as far away as Baltimore, Toronto and Portland, Maine. The USGS National Earthquake Information Center measured the earthquake's depth at 3.1 miles.

From CNN (edited):

Northeast of U.S. quivers in rare quake

April 20, 2002 Posted: 1:58 PM EDT (1758 GMT) The quake caused this road to collapse outside Plattsburgh, New York.

PLATTSBURGH, New York (CNN) -- An unusually strong earthquake was felt across the Northeast United States and parts of Canada early Saturday morning, rattling residents and buckling roads in the region of the epicenter. No injuries or deaths have been reported.

The U.S. Geological Survey confirmed the quake, setting the preliminary magnitude at 5.1 -- capable of causing considerable damage. It was centered 15 miles southwest of Plattsburgh, New York. According to the USGS, the quake happened at 6:50 a.m.

The Canadian Geological Survey reported an earthquake of magnitude 5.5. Frank Revetta, the director of the Northern New York Seismology Center at Potsdam, said the Canadian figure may prove to be more accurate.

Jim King, director of Clinton County Emergency Services, told CNN two aftershocks have been felt -- one about 15 minutes after the initial earthquake, and a second shortly before 9 a.m.

"We're assessing the damage that's been called in," said King. "We have a couple of roads that have failed." He said State Route 9 was closed to traffic because of damage from the quake.

New York Department of Transportation workers began inspecting bridges for possible damage, and a lot of people had called in reports of damage ranging from shattered glass to cracked ceilings and chimneys. King said the county had declared an emergency. Plattsburgh reported no significant damage or injuries.

The USGS said in an earthquake bulletin that "the earthquake was felt from Buffalo, New York to Boston, Massachusetts and Baltimore, Maryland."

Police across the region say they received calls of concern about tremors from New York, New Hampshire, Connecticut and Vermont. There were similar calls in Ontario.

Police in New London, New Hampshire, say they have received a few dozen calls about tremors. A police dispatcher said residents are reporting that the earth shook for 15 to 20 seconds. A dispatcher said the apparent tremors, however, weren't very intense.

When an earthquake occurs, the first information that is processed and relayed is usually based on a small subset of the seismic stations in the network, especially in the case of a larger earthquake. This is done so that some information can be obtained immediately without waiting for all of it to be processed.

As a result, the first magnitude reported is usually based on a small number of recordings. As additional data are processed and become available, the magnitude and location are refined and updated. Sometimes, the assigned magnitude is "upgraded" or slightly increased, and sometimes it is "downgraded" or slightly decreased.

Severe earthquakes have occurred in the eastern United States, but are most commonly associated with the West. The USGS estimates that a magnitude 6 earthquake in November 1775 heavily damaged Boston.

The strongest earthquakes recorded in the continental United States occurred in eastern Missouri near the border with Kentucky and Tennessee, not out West. During the winter of 1811-1812, a series of three earthquakes, with estimated magnitudes of 8.4 to 8.7, occurred near New Madrid, Missouri.

The shocks were so strong that they changed the course of the Mississippi River, church bells rang in Washington D.C. and Boston, and observers reported that the land distorted into visible rolling waves.

There were few deaths or damage because the surrounding area was mostly undeveloped at the time.


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