Small Earthquake Monday Near NY/CT Line

HOLMES, NY — A small earthquake occurred at 6:35 p.m. Monday in Dutchess County, according to both the Lamont-Doherty Cooperative Seismographic Network and the U.S. Geological Survey. The magnitude was 1.3 and it happened about 8 miles down.

Did you feel it? The USGS National Earthquake Information Center asks for citizen scientists to help map the impact. The epicenter of the quake was:

• 1.4 miles north-northwest of Holmes, New York
• 3 miles west-southwest of Pawling, New York
• 6 miles north of Lake Carmel, New York
• 8 miles northwest of Putnam Lake, New York
• 14.6 miles northwest of Danbury, Connecticut
• 16.5 miles east of Beacon, New York
• 17.2 miles north-northeast of Jefferson Valley, New York
• 32 miles west of Waterbury, Connecticut
• 52.5 miles west-southwest of Hartford, Connecticut
• 60 miles) north-northeast of New York, New York

The Lower Hudson Valley is at the north end of the Ramapo Fault System.

A study released in 2008 by seismologists at the Columbia University Lamont-Doherty Earth Observatory in Rockland County discussed the location of the Indian Point nuclear power plants at a previously unidentified intersection between two active seismic zones. The reports’ authors calculated a 1.5 percent chance that a 7.0 magnitude earthquake, a force 32 times the amount the Indian Point plants were designed to withstand, could occur within the next 50 years. The plants are due to close by 2021.

SEE: Indian Point Ranked Highest Quake Risk in U.S.

According to the scientists, quakes have been recorded in New York since colonial times.

Moderately damaging earthquakes strike somewhere in the urban corridor roughly twice a century, and smaller earthquakes are felt roughly every 2-3 years.

Earthquakes in the central and eastern U.S., although less frequent than in the western U.S., are typically felt over a much broader region. East of the Rockies, an earthquake can be felt over an area as much as ten times larger than a similar magnitude earthquake on the west coast. A magnitude 4.0 eastern U.S. earthquake typically can be felt at many places as far as 100 km (60 mi) from where it occurred, and it infrequently causes damage near its source. A magnitude 5.5 eastern U.S. earthquake usually can be felt as far as 500 km (300 mi) from where it occurred, and sometimes causes damage as far away as 40 km (25 mi).
Faults

Earthquakes everywhere occur on faults within bedrock, usually miles deep. Most bedrock beneath the urban corridor was assembled as continents collided to form a supercontinent about 500-300 million years ago, raising the Appalachian Mountains. Most of the rest of the bedrock formed when the supercontinent rifted apart about 200 million years ago to form what are now the northeastern U.S., the Atlantic Ocean, and Europe.

At well-studied plate boundaries like the San Andreas fault system in California, often scientists can determine the name of the specific fault that is responsible for an earthquake. In contrast, east of the Rocky Mountains this is rarely the case. New York City, Philadelphia, and Wilmington are far from the nearest plate boundaries, which are in the center of the Atlantic Ocean and in the Caribbean Sea. The urban corridor is laced with known faults but numerous smaller or deeply buried faults remain undetected. Even the known faults are poorly located at earthquake depths. Accordingly, few, if any, earthquakes in the urban corridor can be linked to named faults. It is difficult to determine if a known fault is still active and could slip and cause an earthquake. As in most other areas east of the Rockies, the best guide to earthquake hazards in the New York - Philadelphia - Wilmington urban corridor is the earthquakes themselves.