|Maryland Geological Survey||Maryland Seismic Network|
|MGS Home | Seismic Network Home | Weekly Helicorder Archive | Today's Helicorder | Helicorder Help ||
|You can view near-real time data from Maryland's Seismic Network.|
| There are several options for viewing Maryland seismic network data. Near real-time data is available through the online helicorder and the online seismograph. Records of recent, significant events detected by the network are found in the local event and global event archives. We also have a simple listing of recent helicorder records in our helicorder archive.
Our seismic data displays are divided into two main categories: global (large, distant) and local (small, nearby) events. Signals generated by global events tend to be of lower frequency and higher amplitude than those caused by local events. Seismic events in and around Maryland tend to generate lower amplitude and higher frequency signals than large, global events. Global seismic events are generally detected by seismometers around the world. Most local events are usually detected only by seismometers nearby and in Maryland. By processing the raw data from our network with a band-pass filter we can separate global event signals from local event signals.
The global and local data are further subdivided into motion components. Our seismometer measures earth motions in three directions: north-south, east-west, and vertical (up and down). The data for each direction are sent out from the seismometer in individual channels: channel N is the north-south channel, E is the east-west channel, and Z is the vertical channel. Measuring these three components gives precise information about the origin and magnitude of seismic events.
| The online helicorder displays daily seismic data from the Soldiers Delight seismometer. There are 3 helicorder records for each day, one for each motion component channel. You can also choose to view either local or global seismic events.
The record for today is near-real time. There is a 5 minute delay between the time the seismometer sends us information and the time it is visible on the Internet. The helicorder day begins at midnight, Coordinated Universal Time (UTC), which is 19:00 EST (7:00 p.m.). More information on UTC can be found at http://liftoff.msfc.nasa.gov .
Please note that our records begin on October 11, 2001, therefore selecting a date earlier than this will not work. Also, we began using filtered, local data on January 2, 2002. Therefore there are no local helicorder records before this date. If you experience difficulty using the online helicorder page you can view a simple listing of recent helicorder records on the helicorder menu page.
For information on how to read our helicorder records, see the Online Helicorder Help page.
| The Labin Online Seismograph displays seismic data from the Soldiers Delight seismometer. The record is near real-time, with only a few seconds of delay. The display is interactive, allowing you to change the amplitude scales. See the Online Seismograph page for more information about seismographs.
The seismograph has been tested on Windows95, 98, NT and 2000 using Internet Explorer 5 and Netscape 4.7. We have had some problems getting the seismograph to work on Macintosh computer. If you have any suggestions on how to get this working on Macs, let us know.
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