Real-time monitoring
KML tags permit network links to remote data servers. The example shown in Table 7 links to a USGS server and allows the user to view earthquakes in near-real time on their Google Earth virtual globe.
Table 7: Network Link Tags for Access to Remote Data Servers
<NetworkLink>
<name>Earthquakes</name>
<Url>
<href>http://earthquake.usgs.gov/eqcenter/catalogs/eqs7day-depth_src.kmz</href>
<refreshMode>onInterval</refreshMode>
<refreshInterval>300</refreshInterval>
</Url>
</NetworkLink>
The refresh mode and refresh interval tags control the way in which the display is kept up to date. Currently, there are no KML sources for focal mechanisms and centroid moment tensor solutions. The author has successfully parsed HTML documents such as those on the USGS NEIC serve, searching for key words (“NP1”, “NP2”, “strike”, “dip”, “slip”) and reading the digits that follow. However, this is an unsatisfactory “hack”-like solution as it is easily broken by a change in HTML page source format. The USGS currently issues email alerts with nodal plane solutions so it should be possible to post the same data in KML format. KML based nodal plane data may thus be expected in the near future.