The UNAVCO Facility has completed an initial emergency response to the November 3 magnitude 7.9 earthquake on the Denali Fault in the Alaska Range. Four campaign receivers from the UNAVCO pool were deployed by University of Alaska, Fairbanks (Jeff Freymueller, PI) staff two days after the quake. A UNAVCO field team (Figure 1) also installed 10 semi-permanent continuous stations during the first two weeks after the earthquake. These stations used Ashtech uZ and Trimble 5700 receivers, and tall antenna mounts to keep clear of snow accumulation. Due to the dark northern winter, power is solely from rechargeable batteries that will be swapped during periodic service visits. Longer lasting air-cell batteries are already slated for the most remote sites. Data retrieval is from manual data downloads or memory card swap, as most sites are in locations with no local communications infrastructure. Upon retrieval, the data will be made publicly available in the UNAVCO archive. Further densification, fortification, and power upgrades (solar and possibly wind turbines) of exisiting sites will occur summer 2003.

Figure 2 shows the distribution of the continuous GPS stations installed, shown as orange dots. The magnitude 7.9 Denali fault earthquake of November 3, 2002 resulted from right-lateral offset along portions of the Denali and Totschunda fault systems in Alaska. Total length of the rupture was at least 300 km (190 miles). Shown here are the epicenters of the November 3 event (red) and the preceding magnitude 6.7 event of October 23, 2002 (blue), as well as two previously recorded large shallow earthquakes (yellow) in the vicinity of the fault. Because there were few seismometers in the region at the time, the locations of the earlier events are poorly constrained. Shown in yellow are other faults that show evidence of activity during Quaternary time (past two million years). Numbers show the locations of some of the following photographs. Figure by Rod Combellick, Alaska Dept. Nat. Resources, Div. Geol. Geophys. Surveys.

For more photos see http://www.dggs.dnr.state.ak.us/earthquake3.htm (requires a fast connection).

For additional information and links, see: http://earthquake.usgs.gov/eqcenter/eqinthenews/2002/uslbbl/index.html
http://web.ics.purdue.edu/~ecalais/projects/denali/.

Last modified Thursday, 04-May-2006 11:05:00 MDT

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