EarthScope GPS Tutorial

PBO Geodetic Instrumentation – GPS Principles, Data Access and

Applications

Chuck Meertens, David Phillips, Freddy Blume,

Mike Jackson, and Greg Anderson

UNAVCO, Boulder, CO

EarthScope in the Northern Rockies Workshop

Bozeman, Mt

17 September 2005

Outline

Science Introduction

GPS – Briefly how it works

Achieving High precision GPS results

GPS Science Examples

PBO Instrumentation

and Data

GEO-EarthScope

UNAVCO Facility-supported PI science includes plate tectonics, boundary zones, earthquakes and tectonics, volcanoes and active magmatic systems, glacial movements and isostatic adjustment, delta subsidence and precision mapping.

GPS Science: Global PI Research Projects

GPS – the global perspective

GSRM Model of Kreemer and Holt

Observed GPSVelocities

Plate TectonicModel with DeformableBoundaries Model Velocities and Plate

Boundary Strain

Global Plate Motions and Boundary Zones

5170 geodetic velocities from 86 different studies

• 24+ satellites• 6 orbital planes• 55 degrees inclination• 20,200 km altitude• 4 satellites in each

plane• 12 hour orbital period• 4 satellites visible

GPS: The System and How it works

Space Segment

Satellite Signal Structure

Carrier phase L1 L2

Frequency 1575.42 MHz 1227.60 MHz

Wavelength 19cm 24cm

Code Modulation C/A-code L2C-Coming…

P(Y)-code P(Y)-code

NAVDATA NAVDATA

Carrier

C/A-code

P-code

NAVDATA

ReceivedSignal

What your Geodetic GPS receiver measures…

Code Range Results

Autonomous Position+/- 10 m (30 ft) error (horizontal)+/- 15 m (45 ft) error (vertical)

Your location is:45o 30.323’ N

111o 45.162’ W

Carrier Phase Solutions

= First Partial Wavelength

N

N = Integer Ambiguity

D

Distance D = N +

For highest precision (mm-level) coordinates use:-Carrier phase to determine ranges-Dual-frequency receivers-Good monuments-Multiple stations-Sophisticated processing software-Collect lots of data

PBO Precision ~1 mm horizontal ~ 3-4 mm verticalFrom daily solutions

Reference Systems

• Precise Orbits• Reference Frames (ITRF and

SNARF)• Earth orientation parameters• Global Plate Motions and other

geophysical effects

You also need Global Tracking Systems for:

NASA Global GPS Network (GGN)Operated by JPL and UNAVCO – get products from the IGS

Reference Frames – ITRF/SNARF

Standard North American Reference Frame (SNARF)

- UNAVCO SNARF Working Group, Geoff Blewitt, Chair

Will provide an improved reference frame that accurately defines the precise coordinates and time evolution of a set of stations representing "stable North America."

ITRF 2000 Velocities (left) compared to a N.America-fixed Reference frame (WUSA, SAO, right)

Permanent Stations

Why Permanent Stations?

1. Improved precision and ability to assess precision- Longer time series- Tendency to invest in better monuments- Better able to characterize error sources

2. Measure transient phenomena- Earthquakes (co-seismic and high-rate), post-seismic,

interseismic - Volcano deformation- Subduction zone aseismic transients- Hydrologic signals- Post-glacial rebound

3. Improved reference frame4. Essential for orbits and clocks5. Economy

- Processing, data handling automated- Fewer personnel in field

6. Synergism with other applications (e.g. ATM, Surveying)

Global Plate Tectonics

Global GPS data are used to construct plate tectonic and strain rate modelsExample: REVEL-2000 from Sella and others, 2002.

Other plate motionModels have been determined from geology and seismology (Nuvel1A) and hot spot tracks (HS3).

UNAVCOPlate Motion Calculator

Also see NGS website for coordinate transformation tool.

Regional Plate Boundary Deformation

Finite Element Model

Observed GPS Velocity Field

Viscosity

L. Flesch and B. Holt

Deformation In the Plate Interior

Horizontal and Vertical Motions from Glacial Isostatic Adjustment

Stable North American Reference Frame (SNARF)

Permanent Stations

Tectonic

Signals

Basin and Range, Yellowstone U. of Utah, Caltech, Harvard SAO

Example of fairly linear motions(~2 to 3 mm/year)

Coseismic and Postseismic deformations for Parkfield 2004 earthquake.

EarthQuake Transients

P067

P278 P576 P526P295

Non-Tectonic Signals

Hydrologic

(non-tectonic

time-dependent signals)

Example from

the Salt Lake Basin

+- 3 cm vertical annual

Signals from spring runoff

(U. Utah)

GPS Seismology

High rate Kinematic GPS….1 hz GPS “seismogram” compared with seismometer, Denali EQ. Bock, 2004.

Reasons to look atHigh rate GPS EQs:

-GPS directly measures displacement (not velocity or acceleration)

-GPS does not clip

…but GPS is considerably less sensitive than a seismometer

EarthScope Instrumentation

• 3.2 km borehole into the San Andreas Fault

• 875 permanent GPS stations• Up to 174 borehole strainmeters • 5 laser strainmeters• 39 Permanent seismic stations

• 400 transportable seismic stations occupying 2000 sites

• 30 magneto-telluric systems• 100 campaign GPS stations• 2400 campaign seismic stations

PBO Permanent Stations

Rocky Mountain

Permanent GPS Stations

Making Stable Monuments –Different options depending on cost, geology, permits

Campaign GPS

EarthScope Campaign GPS

28 Portable Campaign GPS instruments and ancillary equipment purchased and ready for deployment.

72 Portable Campaign GPS instruments and ancillary equipment purchased in FY06.

Rio Grande Rift 5-year proposal funded through ES science

30 instrument Cascadia ETS Campaign for summer/fall 2005 (underway)

Campaign GPS

Come see the new EarthScope/PBO GPS gear in the poster session!

Topcon GB-1000Tech 2000 mast

PBO Campaign – ETS Cascadia

Cascadia Episodic Tremor and Slip Event Principal Investigator (PI): Ken Creager, Dan Johnson & Rick Bennett

UNAVCO staff: Freddy Blume (PBO Project Manager) & Nicole Feldl

Photo Location: Clallam Bay, Washington

30 Portable GPS Systems deployed

EarthScope Operational Status

Shown are PBO GPS Stations with data available from the UNAVCO Archive

GPS Data Flow and Access

The user will get raw data,Solution time series and velocity vectors

Borehole Strainmeters & Seismometers

Long-baseline Laser Strainmeters

Borehole Strainmeter Data Processing

0

1 105

2 105

3 105

4 105

5 105

04-Jan-1 04-Apr-1 04-Jul-1 04-Oct-1 05-Jan-1

Time

0

4000

8000

2004-Jun-24 2004-Jul-1 2004-Jul-8 2004-Jul-15 2004-Jul-22

ST

RA

IN (

CO

UN

TS

)

Time

• BSM Data Analyst: Kathleen Hodgkinson

• First Level 0 data: June 2005

• Pre-processing:– Decimate, linearize, remove tidal & borehole effects– Determine data edits using initial corrections

• Processing:– Edit raw data for outliers, offsets, etc.– Remove borehole trends– Generate tidal correction– Compute areal and shear strain– Convert to XML

• First Level 2 products: Sep 2005

• Similar products from LSM (SIO)

Strainmeter Data Flow and Access

GEO-EARTHSCOPE

EarthScope Imagery and Geochronology

“The EarthScope program invites proposals that include the acquisition of aerial and satellite imagery and geochronology that will examine the strain field beyond the decade time scales available from the PBO geodetic instrumentation.

A goal of EarthScope is the improved understanding of the tectonic evolution of the North American continent. Identifying and understanding deformation rates in all tectonic regimes is critical to reaching that goal.

Proposals should indicate how the imagery or geochronology will contribute to the success of EarthScope.”

2005 NSF EarthScope Announcement of Opportunity

GEO-EarthScope Possibilities

1. Airborne LiDAR image of the San Andreas fault. Courtesy of Ken Hudnut, USGS.2. InSAR image of the Hector Mine earthquake. Courtesy of Howard Zebker, Stanford.3. Ground Control using UNAVCO GPS receiver being deployed on the San Andreas fault to support

an airborne LiDAR survey. Photo courtesy of Francine Coloma, NSIDC.4. Geocronology associated paleoseismology study site on the San Andreas fault near Wrightwood, CA. 5. AMS Lawrence Livermore Accelerator Mass Spectrometer

1.

2.3.

4.

5.

Contact: Dr. David Phillips, UNAVCO/PBO Geo-EarthScope Project Manager

UNAVCO Support

UNAVCO Support Requests

• Permanent Stations

• Semi-permanent Stations

• Campaign Surveys

• GeoEarthScope

Come to UNAVCO

for help with your project

from proposal planning to

project implementation!

For more information…

http://pbo.unavco.orgwww.earthscope.org