ShakeMapple Project - Technical Details
For those interested, here are a few technical points about the ShakeMapple system:
- User information is never shared or exposed.
- Locations displayed on the results map are displayed with limited precision and have random added variation so client locations are never precisely located.
- The ShakeMapple application continuously records the internal accelerometers at 25 samples per second.
- The data is stored in a "circular buffer" file limited to a maximum size of 3.6MB. (A 2 hour buffer.)
- The client does not "detect" earthquakes. Instead, it queries the ShakeMapple servers and only responds when an earthquake has occurred near its location.
- The ShakeMapple client communicates with the ShakeMapple servers using standard HTTP protocol over port 80.
- The client polls (queries) the server every 2 minutes. This is the same approach as (although more frequent than) standard techniques used to find software updates or new versions of installed software.
- There is no inbound communication. The ShakeMapple application does not act as a server nor open ports to the exterior.
- Transmitted information includes only the opaque client identifier.
- In the event of a felt earthquake, the client sends the calculated peak acceleration along with the user-supplied precise location at the time of the earthquake.
- Local files are located under the ShakeMapple.app installation resources directory:
- Data File:
- shakemapple/buffers/buffer.txt (currently limited to maximum size of 3.6MB providing a 2 hour buffer)
- Log Files: