Visualization of Microearthquakes Data
from Enhanced Geothermal System Sites

Contents

Introduction

Geothermal regions around the world provide hot water and steam that can be used to provide heat for homes and businesses and/or to generate electricity. Typically, naturally occurring hot springs are directly tapped to extract hot water and steam. In regions where there is hot rock, but no hot springs, geothermal energy can be produced by by injecting water into hot rock formations and extracting the water that is heated through contact with the formation.

Enhanced Geothermal Systems (ESG) are a new type of geothermal power technology that enhances water flow in hot rock reservoirs by injecting cold water under pressure in order to increase the permeability, and hence the flow of water, in the reservoir. Injecting water under pressure causes naturally occurring fractures to open. The opening of the fractures can be detected by seismometers as microearthquakes. A microearthquake is defined as a very low intensity earthquake (i.e., with a magnitude of 3 or less on the Richter scale).

Visualization of Microearthquakes

Generally, earthquake locations are pinpointed on maps even though the epicenter of earthquakes are not at ground surface. In the case of microearthquakes occurring as a result of enhanced geothermal energy production, it is interesting to look at the 3D distribution of microearthquakes. The images below show microearthquakes that occurred at The Geysers geothermal field in California between October 18 and November 17, 2009. The largest microearthquake that occurred during this period had a magnitude of 2.82 and occurred on November 16. The radii of the glyphs are proportional to the magnitude of the microearthquakes. Note that the scaling of the glypyhs varies from image to image; the larger the number of earthquakes, the smaller the scaling factor used.

 

                 
day view, click to enlarge             week view, click to enlarge             month view, click to enlarge

Making Microearthquake Data From The Geysers Publicly Accessible

The Earth Science Division at Lawrence Berkeley National Laboratory has developed a Web site to provide information about enhanced geothermal systems and induced seismicity, as well as near real-time data on microearthquakes occurring at The Geysers. See the For More Information section below for links to this information.

In order to provide 3D visualizations of the microearthquake data, we installed the visualization and analysis package, VisIt, on the server that receives and archives the microearthquake data from The Geysers. To generate the 3D visualizations shown above, a PHP script calls VisIt to run in command line mode; a Python script is used to control different aspects of the visualization. Though it is not possible for the user to interact with the image generated by VisIt, different viewing angles are available by selecting the desired orientation.

Future Plans

We plan to implement the same technology used to create visualizations of microearthquakes at The Geysers to create visualizations of microearthquakes at Desert Peak & Brady's Hot Springs, also in California. In addition, we plan to install VisIt on a workstation at the Desert Peak/Brady's Hot Springs site in order to provide real-time, 3D visualizations of the earthquake data for viewing by the geothermal plant operators.

For More Information

Earth Sciences Division, Lawrence Berkeley National Laboratory
      What is an Enhanced Geothermal System?
      What is Induced Seismicity?
      Interactive, Real-Time Map of Earthquakes at The Geysers
      Interactive, Real-Time Map of Earthquakes at Desert Peak & Brady's Hot Springs

U.S. Department of Energy
      Geothermal Technologies Program