The Mw 7.9 Denali earthquake
GPS time series

Eric Calais, Andrew Freed, Purdue University
Jeff Freymueller (Geophysical Institute, Fairbanks), Roland Burgmann (UC Berkeley)

Project funded by NSF
Technical support from UNAVCO


The Denali earthquake | Coseismic and early postseismic | CGPS network and position time series | Snapshots of postseismic response

Click on a site to see its position time series

Continuous GPS stations in Alaska. White squares: stations installed in the framework of this project. Red squares: pre-existing continuous GPS stations. Red line: rutpure trace of the Nov. 2 earthquake. Large star: epicenter of the Denali earthquake. Small star: epicenter of the Oct. 23, Nenana Mountain, M6.7, earthquake.


Raw GPS time series: each point in the time series represents a 24-houR solution. Positions as shown with respect to a North America-fixed frame. The Mw7.9 earthquake occured on Nov. 3rd, 2002 = day of year 307, at 22:12 UT.

Raw times series can also be displayed by clicking on the site name below:
CENA | FAIR | CLGO | GRNR | BITS | HIWC | HURC | TLKA | ATW2 | TSEA | KEN2 | AUGL | SELD | CHI4 | POT3 |
GNAA | DH32 | PAXC | ATTC | DLNC | DLTJ | JANL | 299C | LOGC | MENT | DRMC | FRIG | BEA2 | KODK |
DNL1 | DNL2 | DNL3 | USLM |

Download the raw time series here. Format is:
  1. time (decimal years)
  2. observed (mm)
  3. uncertainty (mm)

Modeled times series can be displayed by clicking on the site name below. Blue dots = residuals, Red dots: data corrected for annual and semi-annual noise and for offsets, Black line = model.
CENA | FAIR | CLGO | GRNR | BITS | HIWC | HURC | TLKA | ATW2 | TSEA | KEN2 | AUGL | SELD | CHI4 | POT3 |
GNAA | DH32 | PAXC | ATTC | DLNC | DLTJ | JANL | 299C | LOGC | MENT | DRMC | FRIG | BEA2 | KODK |

We model site positions as the sum of:
  1. A linear term representing secular elastic strain accumulation,
  2. A logarithmic term representing postseismic deformation,
  3. An annual and semi-annual periodic term representing seasonal effects not modeled in the GPS data analysis,
  4. DC offsets due to coseismic displacements, equipment changes or unexplained problems at the site.
The model equation is:

where a, b, ci, d, e, f, g, h, and are estimated by inverting the site position data y using a singular value decomposition scheme. Hi(t) is a binary operator equal to 0 or 1 before or after offset i, respectively. The logarithmic term in the equation above is a convenient means of parameterizing time-dependent postseismic deformation. Although the data is well fit by this model, we do not ascribe a physical significance to the estimated model parameters or predictive power to the overall model. We use this approach only as a curve-fitting convenience to remove non-tectonic effects (seasonal variations and DC offsets) and estimate displacement uncertainties.

Download the modeled time series here. Format is:

  1. time (decimal years)
  2. observed (mm)
  3. uncertainty (mm)
  4. modeled (mm)
  5. residual (mm)
  6. modeled without periodic terms (mm)
  7. observations corrected for offset and periodic terms
  8. observations corrected for offset and polynomial terms
  9. observations corrected for offset, periodic, and polynomial terms
Modelers probably want to use colums 1 and 7...

Some site pictures: 299c | dnlc | drmc | frig | hiwc | hurc | janl | logc | ment