March | 2013 | VOLCANIC TREMORS

Map Key

Earthquake Markers

On the maps each coloured dot orb or marker represents an earthquake, the colours indicate the size range.
The epicentre of the earthquake event is at the base of the orb.

Map Navigation

On the interactive maps clicking on an individual icon will open a small popup tag inside the map frame giving the detail information for that quake.
Once you have finished reading that tag you can simply click in the background map to close that tag and select another if you wish.
You can also move the map around inside the frame by clicking and holding down the left button of your mouse on the map itself, rather than having to use the up/down/left and right arrows.

You can see the earthquake maps in various versions, ie map, satellite, terrain and even Google Earth.

At the bottom of each interactive map is text saying "see larger map". This will open a new page with the same map, but with the icons and magnitudes also as a list. The list is in a ascending time order. You can click on an icon on the map or a magnitude number on the list and a detail balloon (tag) will pop up on the map from the location of the event.

Google Earth Viewing

From here you can also click on the "View in Google Earth" button which will open the kml file in the real Google Earth rather than inside the Google Maps i-frame. This can be handy when you want to see multiple years events together.
You may have to zoom in on the map if you are looking for details of an icon that is in a cluster.

Volcanic Tremors

Earthquakes related to volcanic activity may produce hazards which include ground cracks, ground deformation, and damage to manmade structures. There are two general categories of earthquakes that can occur at a volcano: volcano-tectonic earthquakes and long period earthquakes.

Earthquakes produced by stress changes in solid rock due to the injection or withdrawal of magma (molton rock) are called volcano-tectonic earthquakes (Chouet, 1993). These earthquakes can cause land to subside and can produce large ground cracks. These earthquakes can occur as rock is moving to fill in spaces where magma is no longer present. Volcano-tectonic earthquakes don't indicate that the volcano will be erupting but can occur at anytime.

The second category of volcanic earthquakes are long period earthquakes which are produced by the injection of magma into surrounding rock. These earthquakes are a result of pressure changes during the unsteady transport of the magma. When magma injection is sustained a lot of earthquakes are produced (Chouet, 1993). This type of activity indicates that a volcano is about to erupt. Scientists use seismographs to record the signal from these earthquakes. This signal is known as volcanic tremor.
C.M. Riley. Michigan Technological University

Time

The days and hours, minutes and seconds posted in this blog are UTC time.
This standard is "coordinated universal time", abbreviated UTC. This was formerly known as Greenwich mean time (GMT)

Greenwich mean time was based upon the time at the zero degree meridian that crossed through Greenwich, England. GMT became a world time and date standard because it was used by Britain's Royal Navy and merchant fleet during the nineteenth century. Today, UTC uses precise atomic clocks, shortwave time signals, and satellites to ensure that UTC remains a reliable, accurate standard for scientific and navigational purposes.

Archive for March, 2013