Maryland Seismic Network| Maryland Geological Survey | Maryland Seismic Network |
| Join the Network | contact: Jim Reger (jreger@mgs.md.gov) |
| MGS Home | Seismic Network Home | Today's Helicorder | Helicorder Help | | |
|
You can join the Maryland Seismic Network and view real time data. |
Data from the Maryland Seismic Network is broadcast over the internet for anyone to use. You can capture this data on your computer and display it real-time as it is transmitted from the network. You can also record the data and view and analyze it for yourself. To join the network you need to download and install free software, and configure your computer to receive the seismic data stream. The following are required to join the network: an internet connection
After installing Scream! software configure Scream! to connect to the data stream using the software's network dialog boxes. If you are familiar with Scream! software and know how to us it, all you need to do is use the Scream! network setup dialog box to add these parameters to the "My Client" tab:
If you do not have Scream! or need help installing this software, you can use the resources guidelines listed below to become a part of the Maryland Seismic Network. Please note that our Scream! data stream is often not working due to technical problems with the current version of Scream! server for Linux, which we use to transmit our seismic data. We are trying to upgrade to a more stable version, but until this is accomplished, the seismic data from our web site will occasionally be interrupted. |
|
| A Brief Guide to Setting Up Scream! software | ||
Obtain Scream! software
from Guralp Systems for
Windows or Linux:
Unzip and install Scream! on you computer. As the installation concludes, you can click the "Run Scream" and "View Readme file" in the installation window to start Scream! . When the installation window has closed your screen should appear similar Figure 1 if you opened the README and HELP windows. |
Figure 1. |
|
| You should have the blank Scream! window open (Fig. 2). Right-mouse click the "Network" menu item in the left pane and click on "Configure." The Network Configuration window will open. Click on the "My Client" tab to open the client window. You can also access this dialog box from the " Windows / Network Control " menu item in the main menu at the top of the Scream! window The "My Client" term refers to the fact that your computer will act as a client, receiving information from the Seismic Network server. The "My Server" tab brings up the server screen, but you are not setting up a server, so you do not want the server screen. If you wished to run a seismic data server and distribute information to other computers, you would use the "My Server" tab. You cannot use the "My Server" tab to add the Maryland Seismic Network parameters to Scream! . |
Figure 2. |
|
| You should have the "My Client" window of the Network Control panel open (Fig. 3). Right-mouse click the blank area under the upper "servers" panel with the heading " Servers|Command|Refresh|Comment " to bring up the context menu. Click the "Add..." menu item to open the "Add A GCF Server" dialog box. GCF stands for Guralp Compressed Format, the native data format for the Guralp seismic hardware used in the Network. The Seismic Network broadcasts CGF data and Scream! receives, decompresses and displays this data. You can add more than one server to the "My Client" windows if you know the IP address and port number of other CGF servers. |
Figure 3. |
|
| You should have the "Add a GCF Server" dialog box open. Enter the Maryland Seismic Network IP address and port number in this blank box. The current IP address is 209.70.178.70 and the port number is 1567 . You must enter both these numbers, separated by a colon ( : ) in this box, so the number will look like 209.70.178.70:1567 If the number is not entered in this format, the Network connection will fail. Notice the item at the bottom of the "My Client" window labeled " Port used for all network communications: 1567 ". This default port number is applied to all servers listed in the "My Client" window. When you have entered the IP:port number in the dialog box, click the " OK " button. Be sure to click the " Receive Data " check box near the bottom of the "My Client" window. |
Figure 4.  |
|
| You can test the Network connection by right-mouse clicking over top of the " 209.70.178.70:1567 " item in the "My Client" window (Fig. 5). Click on the " GCFPING " menu item to send a test signal, or 'ping' to the Network server. If this tests fails, a popup window will display the message " Ping timed out ". The most probable causes for this failure are either the Network is temporarily down or you are experiencing firewall problems between your computer and the Network. If your computer is behind a firewall or you are using a router/switch in a home or small office local network, you need to correct the problem. Firewall issues are beyond the scope of this guide, but there are many resources on the internet to assist with firewall problems. Port 1567 must be opened on your firewall, or if you are using a router, you can forward port 1567 to your computer. See your firewall or router documentation for more information, or contact your IT professional or IP provider for help. If you can ping the Seismic Network you are ready to receive data. Right-mouse click the " 209.70.178.70:1567 " item in the "My Client" window and click the " GCFSEND:B " item. This tells the Network to begin sending GCF:B data. |
Figure 5. |
|
| If a connection is established to the Network the " Servers | Command " column will display "UPD:209.70.178.70:1567 GCFSEND:B" and the " Comment " column will contain " discovery2 ", the server name (Fig. 6). The lower " Block# " and " Control " columns will begin to fill up with data lines. If the upper " Servers | Command |Refresh | Comment " pane is displaying the correct information but the lower " Block# | Control "panel is not receiving data, make sure the " Receive Data " check box is checked and the you used "GCFSEND:B" to start the server connection in the above step. If you accidentally used "GCFSEND:L", Right-mouse click " 209.70.178.70:1567 " and click " GCFSTOP ", then click " GCFSEND:B " to restart the data stream. Also be sure the IP:Port number are properly set to " 209.70.178.70:1567 ". If this item is incorrect you can right-click the " 209.70.178.70:1567 " item and delete it, then add it again with the correct numbers. |
Figure 6. |
|
Close the "Network Control" window. After several minutes the Scream! main window should look like Fig. 7. The left pane shows the Network computers "03EARTHWORM2>Discovery2", which are the Network components actually broadcasting the data. The small "  WO2285-S006 " icon represents the remote storage device (SAM) which continuously records data from the seismometer. The data stream collected by the SAM is displayed in the right pane under the " Receive Data " column, and has the "S006" prefix. The "  WO2717-3A27 " icon represents the seismometer, and the seismic data streams generated by the seismometer are identified in the right pane" Receive Data " column, with the "3A27" prefix. Of the various data streams listed in the right pane, the "3A27Z", "3A27N" and "3A27E" are the actual seismic data of interest. |
Figure 7. |
|
| Fig. 8 shows the 3 data streams of interest highlighted. "3A27Z", "3A27N" and "3A27E" are respectively the vertical, north/south and east/west motion components measured by the seismometer. You can view these live data streams by highlighting one or more streams with your mouse and right clicking over the selected items (highlighted in purple) and click " View ", which will open a "WaveView" window. The "WaveView" window is where you can see the live seismic data. You can select a single stream by clicking on it, or select multiple streams by holding down the "Control" (Ctrl) button on your keyboard while clicking on several streams. This allows you to pick more than one stream. You can also double-click on one stream to open a WaveView window, and later drag-and-drop other streams into the open WaveView window. Explore the various menu items in the main Scream! windows to see how you can display and interpret the streams. |
Figure 8. |
|
| The "WaveView" window shows seismic activity for the selected streams. The controls along the top of the windows allow you to change several display parameters. From left to right they are "amplitude", "time scale", "bandpass filter", "block markers", "pause mode", "print", "time cursor display" and "amplitude cursor display". The best place to start is to click the  bandpass filter button to remove low-frequency variations and produce a smoother view. Adjust the amplitude to 1:64 and the time scale to 2. This will give you a good view of seismic activity in the Maryland area. Experiment with different settings. |
Figure 9. |
|
| A typical quite seismic record is shown in Fig. 10. The labels on the left identify the seismometer network number and direction (Z=vertical, N=north/south, E=east/west). The seismometer is quite sensitive and, besides earthquakes, it will detect wind, rain, acorns falling, and almost anything that can put energy into the ground. Something that looks like a large earthquake might actually be a small blast at a nearby quarry, or a tree limb falling in the area. The seismic signal must be combined with other seismic stations in the area and analyzed in order to determine if an earthquake has occurred, and when and where it has happened. More information about Scream! can be found in the Scream! help files and the resources listed below. Read the Scream! documentation to learn how to record data on your computer and read and analyze it with free Guralp software. |
Figure 10. |
|
| Scream! Resources on the internet | |
|
|
| updated
8/13/08
| Return to previous page | Go to the Seismic Network Home Page | Go to the MGS Home Page | |