The basic principle here is to use our program to generate a KML file that includes recent earthquake activity and then load that KML file into either Google Earth or Google Maps. Several features are adjustable, so you can customize the presentation of the data to your needs. Before we get too deep into that though, let's look at the simplest example and how to get the data into Google Earth or Google Maps.

If you just want to do some quick experimenting with GeoZipper files, we recommend using Google Maps for now. The next paragraph describes working with Google Earth. Working with Google Maps is simply a matter of opeing a new browser window or tab and entering maps.google.com in the address bar.

If you haven't done it already, install Google Earth. Make sure you save anything else you're working on and close the related programs. You can download Google Earth here. The download button was at the upper right corner of the page when I wrote this.

Once you have Google Earth installed or a browser window open for Google Maps, head over to our GeoZipper program here. This link should open a new window (or tab if you use tabbed browsing). There is also a link at the top of this page so you can go right to it in the future.


Loading the GeoZipper KML file into Google Earth/Maps
You will see two sections on that page. The top section is for selecting how you want to modify the presentation of the data. You should see a number of comments in green and parenthesis. These list the default values. You don't actually need to change anything just to get data. I've set the defaults to what I suspect will be the most useful to the most people. So let's just start with those values.

Click the button that says 'Generate New KML File'.

You should see something similar to the following on that page:



The first line in that section will tell you whether we had any issue retrieving the earthquake data we use. It should be extremely rare, but if the first line does NOT say 'Earthquake file found' you should try again a little later as our source at USGS.gov may be very busy or temporarily down.

The next line will tell you the number of groups created. In short, we group the earthquakes geographically and the number of groups is dependent on the 'Group Size' and the number of earthquakes available to process. 'Group Size' can be found in the controls at the top of the same page. Our method of grouping is to essentially measure the distance between consecutive earthquakes and if the distance is greater than what is set in the 'Group Size' control at the top of the page we stop grouping and start a new group. You can see this more clearly if you turn on the 'Lines' control, but we'll talk more about that in a moment.

The third line gives you links for either KML or CSV files. Here is where the process for Google Maps diverges from that for Google Earth. For Google Earth, try clicking on the link for the KML file. For Google Maps skip the next two paragraphs.

Google Earth: You should then see a dialog box pop up with an option to either open the file with a program or save the file. The options available will depend on your browser and operating system (i.e. Windows or Mac). If you have the option to open the file with a program, try selecting Google Earth as this will automatically load the file into Google Earth for you. If you don't have that option, read on and we'll cover what to do with a saved file in a moment.

If all goes right, Google Earth will load the file, zoom out to fit the entire earth in frame and center on the Prime Meridian. It should look something like this:

Google Maps: Copy the following text:

http://www.thematicattic.com/kml/geozipper.KML

Then go to the window or tab with Google Maps and paste the above text into the search box and hit the 'Search Maps' Button.
Google Earth™ with GeoZipper KML file loaded. There weren't any large earthquakes within this view when this picture was captured. (Click for larger image)Google Maps with GeoZipper KML file loaded and in 'Hybrid' mode. This image was captured on Nov. 14,2007 within hours of a 7.7 earthquake in Northern Chile.

If you didn't have the option to load directly into Google Earth, you can also save the file. So go ahead and save the file to a convenient location that you'll remember. Saving the file won't work for Google Maps unless you have a way to post that file somewhere on the web as you need a web address for the search box in Google Maps.

To load the KML file into Google Earth, open up Google Earth and go to the file menu. On the file menu click 'Open'. Then navigate to where you saved the geozipper.KML file. When you find the KML file, either double click or highlight it and click the 'Open' button. The method will depend on your preference and how your operating system works with the Open dialog. Google Earth should then load the file and 'fly' to the prime meridian as in the picture above.


Exploring in Google Earth (Skip to next section for exploring in Google Maps)
Now we can do a little exploring. if you left all the values at default as suggested, you should see pictures similar to what we present below.

Navigation in Google earth is fairly simple. Just click on the earth and drag it around to whatever area you want to explore. Since we don't have any earthquakes in the initial view as of this writing, lets navigate around to North America. Click on the center of the 'globe' and drag to the right (you might have to drag a couple of times turn the globe to the general area of North America).

Your globe may now be centered more towards Central America. Simply click and drag downwards to get North America entirely in the picture.

Now we have North America, but odds are the 'globe' isn't oriented to the north as in the picture below:

Google Earth™ with GeoZipper KML file loaded. We've rotated the 'globe' to fit North America in the picture, but it's not oriented to the North yet. (Click for larger image)

Now take a look at the compass in the upper right corner of the picture. If you hover your mouse over that compass, you'll get a larger version with navigation buttons. Look for the 'N' button where North is currently. If you double-click that button, the 'globe' will rotate to make North at the top of the picture.

At this point, if you look carefully, you will probably see a number of bright green 'paddles' along the West coast of the United States and up along the South and West portions of Alaska. These are highly active areas and will often have green paddles. The paddles represent earthquakes and if you kept the default values as recommended above will represent all quakes in the last seven days that were at or above 2.0 on the Richter Scale. At the time this documentation was updated there weren't very many earthquakes above 2.0, so I lowered that setting to 1.0 for clarity.

Recently the San Francisco area has been a bit more active seismically. We can zoom in on San Francisco rather easily. Look to the left side of the Google Earth program near the top. You should see a box with the words 'Fly to'. Enter 'San Francisco,CA' in that box and press the button to the right. The globe will spin a bit and then zoom in on San Francisco. However, we may be zoomed in a little too much to see any pattern in earthquakes. To zoom out, hover your mouse over the compass in the upper right again. To the right of the compass you will see a line running up and down with a plus button on the top and a minus button on the bottom. Clicking the plus button will zoom in and clicking the minus button will zoom out. There is also a bar in the center. If you move that bar up it will zoom in and moving it down will zoom out. Finally, if you have a mouse with a scroll wheel, you can use that to zoom in and out. Go ahead and play around with the controls to see what suits you best. When you get comfortable, try zooming out to make your view appear roughly the same as the picture below. Los Angeles is near the bottom center.

Google Earth™ with GeoZipper KML file loaded. We've centered our picture around San Francisco,CA and zoomed to see a large area around it. Earthquake activity is represented by the bright green paddles. (Click for larger image)

Now let's try looking a bit more closely at one of the clusters of earthquakes. North and East of San Jose (see above picture) you will see several bright green paddles that line up fairly well. You may also see that they follow what looks like a mountain range. There is another paddle a bit further West, but it doesn't quite follow that line. To make this clearer I've added some more data from USGS that shows fault lines which haven't had activity for over 150 years. We'll discuss adding other sources of data later. In this case it's near an older a lesser known fault zone called the 'Calaveras Fault Zone'.

Google Earth™ with GeoZipper KML file loaded. We've centered our picture around San Francisco,CA and zoomed to see a large area around it. Fault lines added to show coincidence of recent earthquakes. (Click for larger image)


Exploring in Google Maps
Now we can do a little exploring. If you want your images to match ours, the first thing we need to do is switch the display mode.

In the upper right corner of the map in Google Maps you'll find a series of rectangles. Depending on the region you are exploring there may be more or less of these 'buttons', but there should always be three of them available: 'Map', 'Satelite' and 'Hybrid'.
Navigation in Google Maps is fairly simple. Just click on the map and drag it around to whatever area you want to explore. Lets navigate around to North America. Click on North America and drag to the left or right.

Your map may now be centered more towards Central America. Simply click and drag downwards to get North America centered in the picture.

Unlike Google Earth, Google Maps always keeps the map oriented to the North.

At this point, if you look carefully, you will probably see a number of different colored 'paddles' along the West coast of the United States and up along the South and West portions of Alaska. These are highly active areas and will often have colored paddles. The paddles represent earthquakes and if you kept the default values as recommended above will represent all quakes in the last seven days that were at or above 2.0 on the Richter Scale.

Recently the San Francisco area has been a bit more active seismically. We can zoom in on San Francisco rather easily. Look to the upper left side of the Google Maps map. You should see four directional arrows and below them a vertical line with graduated markings. Re-Center the map near Northern California. Just get it close, don't worry about getting it exact. Now look back at the vertical line with graduated marks. That's the zoom control. Click the '+' button at the top of the line. That should zoom in on the map. You can hit the '+' button as many times as you need to get in close on San Francisco. If you get too close, you can use the '-' button at the bottom of the line to zoom back out. You may also need to re-center the map a few times by dragging it with your mouse. Once you get the hang of it, zooming in and out on a region is fairly simple. If your mouse has a scroll wheel, you may also be able to use that to zoom in and out. Now look at the paddles around San Francisco. We may be zoomed in a little too much to see any pattern in earthquakes. Simply zoom in and out until you have a suitable balance between groups of earthquakes and map data like place names or geographic features of interest. When you get comfortable, try zooming back out to make your view appear roughly the same as the picture below. Los Angeles is in the lower right corner.

Google Maps™ with GeoZipper KML file loaded. We've centered our picture around San Francisco,CA and zoomed to see a large area around it. Earthquake activity is represented by the green paddles. (Click for larger image)

Now let's try looking a bit more closely at one of the clusters of earthquakes. North of San Jose (see above picture) you will see a large number of bright green paddles that line up fairly well. You may also see that they follow what looks like a mountain range. There is one a bit further West, but it doesn't quite follow that line. In this case those quakes are likely along a fault zone. With Google Earth we could add in known fault zones, but even with Google Maps we can see a bit of a pattern. To be fair, I changed one of the GeoZipper settings to show earthquakes as small as 1.0 on the Richter scale which very few people would feel, but in some cases that can help show patterns with a bit more detail. Green paddles with diamonds are for quakes of 1.0 to 2.0 magnitude whereas green paddles with stars are for 2.0 to 3.0 quakes.

Google Maps with GeoZipper KML file loaded. We've centered our picture near San Jose,CA and zoomed to see a large area around it. (Click for larger image)


Labels
O.K., So we can see that the earthquakes are related, but how big are they really. In Google Earth, the magnitude shows next to each paddle. Earlier versions of GeoZipper allowed you to turn off display of magnitude, but for now the reasons are quite technical for this shortcoming. Google continues to update and improve the interfaces I use to make this all work, so I'll fix it before too long. Google Maps does not display anything next to the paddles. That said, there are four other bits of data you can make appear next to each paddle in Google Earth. If you select more than one item for the label, GeoZipper will arrange them with parenthesis '()' and/or square brackets '[]'. Also, another anomaly of the interface issue mentioned above is that if you select an item for the label other than the magnitude and don't select the magnitude then the magnitude can be removed. Again, I'll fix this soon.

Google Earth™ with a REVISED GeoZipper KML file loaded. We've re-centered our picture around an area in Chile that suffered a major earthquake on Nov. 14, 2007. It shows the main earthquake and several aftershocks as well as magnitude, date and times they occurred. (Click for larger image)

You may have to click on the image above to see things a little more clearly, but once you do, take a look at North-Eastern earthquake. That's the main quake. The others are the aftershocks with their respective times. You could try to read all of the times and figure out what order they came in, but there's actually an easier way to do this and we'll cover that in the 'Lines' section. Now try clicking on any of the paddles. If the paddle splits into multiple points when you click, you may have more than one copy of the KML file loaded. Look to the left in Google Earth in the 'Places' pane under 'Temporary Places'. If you you see more than one entry titled 'Thematic Attic Unzipping Geology', uncheck all but the first one. Then try clicking on the paddle again and you will see a bubble pop up like the one below (the bubbles work in Google Maps too ... only the labels are missing):

Google Earth™ with a REVISED GeoZipper KML file loaded. We've zoomed in around a couple of earthquakes because they were close together and clicked on one of them to see more detailed information. (Click for larger image)Google Maps with an equivalent file to the one from Google Earth to the left. (Click for larger image)


Bubbles
This is one place where GeoZipper gives more data than the standard KML files you can get from USGS. The first line will tell you which group the earthquake is in. We'll talk a bit more about groups later. Below this is the date and time which are in GMT. Since different seismic recording stations are in different timezones, there needed to be a standard. Below the date and time is a restatement of the Magnitude. This is in case you have labels turned OFF and you click on one of the paddles. Below the Magnitude is the calculated energy released in that earthquake. Scientists use Ergs as a standard unit of energy, but below that line is the same energy converted into Kilowatt Hours. Finally below that is the depth of the quake in Kilometers. If you are a math teacher looking at this, possible exercises for your students could include conversion of the energy released into some unit that could be used to get a good idea of just how much energy is released in even a minor earthquake. Alternatively, the electrical consumption of a city, state or entire country could be looked up for comparison to the kilowatt hours given. Other possible exercises could include looking up the region an earthquake occurred in to find out about the people or businesses.


Now that we've got the basics down, let's look at some of the more advanced features. Keep in mind that each time you load the KML file into Google Earth it keeps the old one (Google Maps replaces the file), so you'll want to uncheck all the old ones to avoid multiple copies of the same points. Once you get used to the system you'll likely be selecting all your options at one time so this won't be as much of an issue.


Lines
You can draw lines from one earthquake to another in chronological order. Simply check the box next to 'Lines' in the GeoZipper program. here's an example of what a GeoZipper KML file looks like with Lines and Labels turned on.

Google Earth™ with GeoZipper KML file loaded using Lines and Labels options. Now you can not only follow the earthquakes in time, but by following the lines. (Click for larger image) Google Maps with GeoZipper KML file loaded using Lines and Labels options. This is the same as the picture to the left but as viewed in Google Maps. Labels don't appear, but lines do. Google Maps has less image data available here, thus the gray area in the upper left of the image. (Click for larger image)

Once lines are added to a GeoZipper KML file, they can be turned on and off. All you need to do is expand the 'Thematic Attic Unzipping Geology' file under 'Temporary Places' in the left panel in Google Earth. Google Maps has a similar left panel with checkboxes for turning things on and off. Unfortunately, as of this writing Google Maps expands all items by default so it make take a little scrolling up and down to find the 'Lines' folder mentioned below. In Google Earth, click on the plus sign to expand the outermost folder. You will see 'Earthquakes', 'Lines' and 'MidPoints' folders within this main folder. Simply Checking or unchecking the 'Lines' folder will turn the lines on and off.


Groups
Sometimes the data as presented can be a bit confusing when there are too many data points and you are drawing lines between them. To clean up the number of lines clustered together, we can reduce the Group Size by changing the number in that box in the GeoZipper program. If we reduce Group Size from the default of 3.75 degrees down to, for example, 1.0 degrees, that would make the groups smaller, but would also make the number of groups larger. As a teacher, if you wanted to set the number of groups to, for example, the number of students in your class, you might need larger groups. As I mentioned before, the groups are determined by how far each subsequent earthquake is in relation to the previous one. The measurement in degrees is relative to the 360 degrees (in any direction) in the circumference of the earth. These are the same degrees used in Latitude and Longitude measurements. One caveat though, our system doesn't take into account the change in direction around the International Dateline or at the Poles. Earthquakes around Northern California are shown below.

Google Earth™ with GeoZipper KML file loaded. Lines are turned on, Minimum Magnitude changed to 1.0 and Group Size has been changed to 0.5 degrees for clarity. Without labels turned on, Google Maps would be quite similar. (Click for larger image)

Let's suppose for a moment, that you are only interested in one group of earthquakes and wish to suppress all other groups from the display in Google Earth or Google Maps. Once you have your group size or number of groups the way you want, you may notice that the group names are simply numbers. This is because it is far more complex to associate a group with a geographical location as you might have expected. There is no way to programatically guess which city or region you want associated with a group. There could be two or more large metropolitan areas within the same group or none at all. So we leave the groups as only numbers. All is not lost for isolating your group though. If you click on any earthquake within a group in Google Earth, the group number will appear in the resulting pop-up bubble. From there, you could uncheck all earthquakes in the left panel of Google Earth or Google Maps and then only check that group. Below is an example of the previous map after isolating a group of earthquakes.

Google Earth™ with GeoZipper KML file loaded using same options as the previous example, but with group 23 isolated. (Click for larger image)


Min. and Max. Magnitude
Considering that most earthquakes under 3.5 are not even felt, we have another way to reduce the number of quakes clustered in an area without having to change group size. In fact, simply excluding earthquakes by magnitude will reduce group size which could make for more manageable assignments for students where their assigned 'group' is in a seismically active region. Simply enter numbers different from the defaults in the 'Min. Magnitude' and/or 'Max. Magnitude' fields in the GeoZipper program and load the resulting KML file into Google Earth or Google Maps.

Google Earth™ with GeoZipper KML file loaded using Lines and Labels options with everything else at default. This is a view of the Bering Strait but the lines get a bit hard to read. (Click for larger image) Google Earth™ with GeoZipper KML file loaded. Lines are turned on, Min. Magnitude has been changed from default (2.0) to 3.5, and Group Size changed from default (3.75 degrees) to 5 degrees. This shows the same view of the Bering Strait in six groups. (Click for larger image)


Data (Only applies to Google Earth for now)
There are three options for how far back we can retrieve data. Up until now we've been retrieving 7 days which is the largest amount of data available through USGS in the format we use. We also have the option to retrieve the last day and the last hour, which might be useful if you just want to, for example, check earthquake activity on a daily basis. There are a few things to keep in mind with this option.
  1. If you save the files generated by GeoZipper rather than loading them directly into Google Earth you can build your own library. The caveat is that the KML files integrate the options you selected when you generated the file. If you just want raw data, there is also an option to download a CSV file with the same data but not the visual effects. With the raw data though, you have to have a paid version of Google Earth to open it.
  2. The data provided to us by USGS are essentially time delayed versions. The 'Last 7 days' option includes 7 days, but not the last 24 hours. The 'Last day' option includes 24 hours, but not the most recent hour. And the 'Last hour' option includes sixty minutes, but not the most recent minute. Still this data can be considered quite useful.
  3. It may already be obvious, but if you are looking for trends in the data you will have a better chance of finding them with more data (i.e. Last 7 days) than less (i.e. Last Day).

Scaling
Scaling has been disabled in the current version because Google Maps doesn't support it and having it actually caused problems with the output. Google is still working on KML in Google Maps, so I'll get this working again when they get it working. In the meantime, earthquake paddles are color and figure coded from green to red and from diamond to star respectively for small to large earthquakes. I'll leave the following description intact for now, but you may ignore it unless your just curious. In some cases you may find that a large number of earthquakes are clustered together. This could represent a main earthquake and several aftershocks. This could also represent something like a mining operation where there would be a large number of what look like earthquakes but are actually explosions use to loosen earth needed to retrieve what is being mined. If the Labels we introduced above start running into each other and making it hard to see the relative size of earthquakes, you can use the Scaling option. That will make the size of the dots larger or smaller depending on the magnitude of individual earthquakes. Also, you may have noticed in some prior examples or while exploring on your own that the dots representing earthquakes are actually color coded. They range from green for the smallest magnitudes to red for the largest magnitudes. Most large quakes I've seen on the news lately only approach orange in color. Here is an example of a view with Scaling turned on and off. I've returned to the area south of San Jose along the San Andreas Fault Zone and turned the mapping of the fault line back on.

Google Earth™ with GeoZipper KML file loaded with Min. Magnitude set to 1.0 and Labels turned on. This demonstrates clustering and difficulty separating out larger earthquakes. (Click for larger image) Google Earth™ with GeoZipper KML file loaded with Min. Magnitude set to 1.0, Scaling turned on and Labels turned off. This shows the same view around the San Andreas Fault Zone but without labels and using scaling. It is clear here that only a couple of earthquakes were even remotely significant in magnitude. (Click for larger image)


Midpoints
In the background section for the GeoZipper program I mentioned the original theory that earthquakes around fault lines might 'bounce' back and forth across the fault line and appear to move up or down the fault line looking something like a zipper. If this was true, I further theorized that the midpoints between the locations of subsequent earthquakes would likely follow the fault line itself. The 'Midpoints' option was designed to show those midpoints as yellow paddles. Also, when selecting the midpoints option, the locations of all earthquakes in the group are averaged for a sort of center of the activity and that is indicated by a white paddle. Let's take a look at Nov. 14,2007 activity in Chile as an example with everything else set at default. The major fault line nearby is actually in the ocean, but it's a subduction fault so there can be activity further into the top plate as one slips under the other.

Google Earth™ with GeoZipper KML file loaded with midpoints (and an average point) for seismic activity on Nov. 17,2007 in Chile. Data for tectonic plates has been added to see potential stresses that may have caused the earthquakes. The lines aren't exactly forming a zipper form, but do help show how the midpoints are in between earthquakes. (Click for larger image)

Midpoints, like Lines, can also be turned on and off as long as you select MidPoints when generating the GeoZipper KML file. To do this, look in the left panel of Google Earth or Google Maps and find the 'Midpoints' folder. You can turn MidPoints on and off by checking and unchecking the checkbox for that folder. You can also turn on MidPoints for selected groups as described for Lines above.


Additional Data Sources
Now that you know how to use GeoZipper, you can enhance the presented data with data from other sources. The key to using that other data is to download it first and then load it into Google Earth using the File menu and the Open option. You might also be able to load directly using the 'Open this file using' option when you click on a link and select Google Earth, but remember that it will be loaded into the 'Temporary Places' folder.

If you would like to see Tectonic Plate Boundaries, one source is USGS which has many resources. They have the files on this page. There is also a link to this in the "What You'll Need" section above. Look for the section titled "Google Earth KML". There are two files available for download on this page (There are more if you click the "More Google Earth files" link). One has the past seven days worth of earthquakes colored by Age, and the other has the past seven days of earthquakes colored by Depth. GeoZipper color codes by Magnitude. Both files though include more than just the earthquakes. They also include the Tectonic Plate Boundaries. Once you have the file loaded, you have the option of turning off the earthquakes from these files by unchecking the "Earthquakes" folder under "USGS Real-Time Earthquakes". You may also want to uncheck the "Legend" folder when you turn off the earthquakes to avoid any confusion with GeoZipper data.

If you want to see detailed fault lines, you can find that data on this page. Please note the USGS request to provide proper acknowledgement. All of OUR data is based on USGS data and we thank them for making it available. If you click on the link that says "Google Earth files" you will be taken to a page with a description of the five files available for download. Click one more time on the "Download files" link and you wil be taken to the listing of the actual files. In this case the files have the ".kmz" extension. This is a zipped form of the KML files which save space and which Google Earth understands without any extra work on your part. For the examples above, I used the "HistoricFaults.kmz" file and I left only the San Andreas Fault Zone items checked. The "Historic Faults" file has Fault Zones that have moved within the last 150 years. All of the other files are for Fault Zones that have moved earlier than that.


A warning about loading multiple KML/KMZ files.
Some KML or KMZ files can get rather large with a LOT of data. This is especially true of the Fault Zone files. The more data you load into Google Earth, the slower it will go. That is why I tend to turn off anything I don't really need by unchecking the corresponding folders in the left side panel of Google Earth. Also, the default installation of Google Earth comes with a lot of cool features turned on on the left side panel. Did you notice that none of my examples above had roads showing? That's because I turned off almost everything except the "Terrain" (not absolutely necessary and might speed things up a bit), "Populated Places" and some "Alternative Place Names" in the layers section of the left panel.


That's it until I think of something else ... Enjoy!
Ed Michel (Webmaster ThematicAttic.com)
September 10, 2007
(Updated September 14, 2007)