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Current Helicorder Displays

MCNB Vertical Short-Period
MCNB East-West Short-Period
MCNB North-South Short-Period

MCNB Vertical Long-Period
MCNB East-West Long-Period
MCNB North-South Long-Period

MCNB Vertical Broadband Low Gain

Recent Helicorder Displays

MCNB HHZ 11 00 : McAdam: Vertical Component, Short-Period
06/28/2017 | 06/27/2017 | 06/26/2017 | 06/25/2017 | 06/24/2017 | 06/23/2017 | 06/22/2017 | 06/21/2017 | 06/20/2017 | 06/19/2017 | 06/18/2017 | 06/17/2017 | 06/16/2017 | 06/15/2017

MCNB HHE 11 00 : McAdam: East-West Component, Short-Period
06/28/2017 | 06/27/2017 | 06/26/2017 | 06/25/2017 | 06/24/2017 | 06/23/2017 | 06/22/2017 | 06/21/2017 | 06/20/2017 | 06/19/2017 | 06/18/2017 | 06/17/2017 | 06/16/2017 | 06/15/2017

MCNB HHN 11 00 : McAdam: North-South Component, Short-Period
06/28/2017 | 06/27/2017 | 06/26/2017 | 06/25/2017 | 06/24/2017 | 06/23/2017 | 06/22/2017 | 06/21/2017 | 06/20/2017 | 06/19/2017 | 06/18/2017 | 06/17/2017 | 06/16/2017 | 06/15/2017

MCNB HHZ 11 01 : McAdam: Vertical Component, Long-Period
06/28/2017 | 06/27/2017 | 06/26/2017 | 06/25/2017 | 06/24/2017 | 06/23/2017 | 06/22/2017 | 06/21/2017 | 06/20/2017 | 06/19/2017 | 06/18/2017 | 06/17/2017 | 06/16/2017 | 06/15/2017

MCNB HHE 11 01 : McAdam: East-West Component, Long-Period
06/28/2017 | 06/27/2017 | 06/26/2017 | 06/25/2017 | 06/24/2017 | 06/23/2017 | 06/22/2017 | 06/21/2017 | 06/20/2017 | 06/19/2017 | 06/18/2017 | 06/17/2017 | 06/16/2017 | 06/15/2017

MCNB HHN 11 01 : McAdam: North-South Component, Long-Period
06/28/2017 | 06/27/2017 | 06/26/2017 | 06/25/2017 | 06/24/2017 | 06/23/2017 | 06/22/2017 | 06/21/2017 | 06/20/2017 | 06/19/2017 | 06/18/2017 | 06/17/2017 | 06/16/2017 | 06/15/2017

MCNB HHZ 11 03 : McAdam: Vertical Component, Broadband, Low Gain
06/28/2017 | 06/27/2017 | 06/26/2017 | 06/25/2017 | 06/24/2017 | 06/23/2017 | 06/22/2017 | 06/21/2017 | 06/20/2017 | 06/19/2017 | 06/18/2017 | 06/17/2017 | 06/16/2017 | 06/15/2017

Explanation

These displays, updated every minute, show records of ground vibrations (seismograms) measured by a seismometer jointly operated by the University of New Brunswick's Department of Earth Sciences and Earthquakes Canada. The seismometer is currently located at seismograph station MCNB in the village of McAdam, in southwest New Brunswick. The seismograms are plotted in the format of old analog (pen on paper) drum recorders known as helicorders, showing 24 hours of data on a single page. The seismogram is "read" like a book, from left to right and top to bottom (this is the direction that time increases). The colors of the horizontal lines change from one hour to the next for ease of viewing.

Time is indicated in the left margin in local time (AST or ADT) and in the right margin in Coordinated Universal Time (UTC).

The vibrations associated with seismic waves arriving from large, distant earthquakes may be detectable by a seismograph for tens of minutes or longer. Seismic waves arriving from smaller but closer earthquakes may be just as strong or stronger, but will typically appear shorter in duration. Commonly, one can recognize the arrival of different wave types: P waves (also known as primary or compressional waves -- the fastest and first to arrive), S waves (also known as secondary or shear waves), and surface waves.

Waves from local or regional earthquakes are relatively rich in short-period (high frequency) vibrations and are therefore most likely to appear on the short period helicorder displays. Waves that have travelled from more distant earthquakes may be more evident on the long-period (low frequency) helicorder display.

Not all the wiggles seen on the seismograms are due to earthquakes. Anything that produces ground vibrations can be recorded. For example, seismograms are commonly noisier on windy days as wind gusts are transferred to the ground through tree roots. Alternatively, a car passing by the seismometer may generate noise that appears "spikey" in appearance on the time scales shown here.

Technical Notes: