g. colosimo, m. crespi, a. mazzoni vadase - a new · pdf filei embedded in a receiver...

Summary GPS Seismology VADASE Conclusions GEO Work Plan (2012-2015)

G. Colosimo, M. Crespi, A. MazzoniVADASE - A new approach to real-time estimate coseismic displacements for near-field tsunami forecasting 1 / 14


Summary

GPS SeismologyIntroduction and state of the artThe main goal

VADASEHow does VADASE work?Results on past strong earthquakesTohoku-oki Japan earthquake

Conclusions

GEO Work Plan (2012-2015)VADASE and GEO Work Plan (2012-2015)



Introduction and state of the art

GPS for GeophysicsI GPS has been supporting geophysical studies for a long time

(about 400 IGS and hundreds to thousands of other permanent stations),I Studies focused on long-period deformations

(plate tectonics, crustal deformation, post-glacial rebound, subsidence)I GPS permanent stations operated with an acquisition interval ≥ 30 sI data analyzed to yield one position per day

I Impossible to estimate rapid or short-duration motions (earthquake waves)

Advances in receivers technology and algorithmsI Acquisition rates of 20 Hz (and even more) commonly availableI Algorithms to obtain one position per epoch

GPS SeismologyI Using GPS to estimate receiver coseismic displacements and waveformsI Fundamental benefit w.r.t. seismometers: no saturation



Introduction and state of the art

Two well established strategiesI Instantaneous positioning

I uses differential positioning and requires a network of GPS permanentstations permanently linked together, with interdistances limited to fewhundreds kilometers

I Precise Point Positioning (PPP)I requires ancillary precise products (satellites orbits and clocks, Earth

Orientation Parameters) not available in real-time with the due accuracy

Tsunami early warning: a major challenge for GPS SeismologyResolutions taken at the Real Time GPS Science Requirements Workshop(September 2007, Leavenworth, WA, USA):

I 1 cm GPS displacements accuracyI in a global reference frameI within 3 minutes after the earthquake



The main goal

The objectiveSo, let focus on

I (near) real-time accurate displacements (NOT positions)I in a global reference frame

The idea: keep it fast, keep it simple!The main goal of this investigation

I to directly estimate displacements from the observations of astand-alone GPS receiver (single station approach)

I just using measurements and information acquired by the receiver inreal-time



How does VADASE work?

The brand new variometric algorithmThis is the basic idea of VADASEVariometric Approach for Displacements Analysis Stand-alone Engine

How does VADASE work? - The variometric equationI we start from the ionosphere-free phase observation, and we consider the

time single-difference between two consecutive epochsI we estimate the receiver displacement epoch-by-epoch (that is its velocity)

from the variation of the geometric ranges receiver-satellites between twoconsecutive epochs (variometric algorithm)

I therefore, we can say that we are using the GPS as a velocimeterI waveforms can be reconstructed integrating the estimated velocities



Results on past strong earthquakes

Analyzed earthquakesVADASE has been tested over several strong earthquakes, for which theresults already obtained by different research groups were available

I Denali, Alaska (MW 7.9, November 3, 2002, 22:12:41 UTC)I L’Aquila, Italy (MW 6.3, April 6, 2009, 01:32:39 UTC)I Chile (MW 8.8, February 27, 2010, 06:34:14 UTC)I Baja California, Mexico (MW 7.2, April 4, 2010, 22:40:42 UTC)

AcknowledgementsI “Impressive” [Prof. T. Herring, MIT Boston, USA], June 2010I Pending Patent by “Sapienza” University of Rome ever since June 2010I DLR Special Topic Prize — European Satellite Navigation Competition,

October 2010I Audience Award — Most voted out of more than 100 ideas — European

Satellite Navigation Competition, November 2010G. Colosimo, M. Crespi, A. MazzoniVADASE - A new approach to real-time estimate coseismic displacements for near-field tsunami forecasting 7 / 14


Tohoku-oki Japan earthquake

Tohoku-oki Japan earthquake, Mw = 9.0I VADASE provided the first

displacements computation at IGSsites MIZU and USUD (1 Hz)

I [IGSMAIL-6358] - March 11,04:13:35 PST 2011

I solutions published on theTohoku-oki Event SupersiteWebsite - March 12, 2011

I “Excellent work”[Prof. K. Larson, University ofColorado, Boulder]

Cover storyGIM International

vol. 25, n. 5, May 2011




Comparison with independent a-posteriori solutions

Software and solutionsI differential positioning: GAMIT kinematic GPS processing module

(TRACK)I Precise Point Positioning: Automatic Precise Positioning Service (APP)

VADASE resultsI overall accuracy (RMSE of the differences) generally better than 10 cm for

all the components (East, North, Up)I average accuracy around 5 cmI compliant with the requirements for real-time fault determination for

near-field tsunami forecasting for strong earthquakes



Conclusions - VADASE: a brand new approachAble to retrieve waveforms

I in real-time (broadcast products)I in a global reference frameI on the basis of high-rate (1 Hz or more) carrier phase observations

collected from a stand-alone GPS receiverI with an accuracy compliant with the requirements for near-field

tsunami forecasting for strong earthquakeI and now also with

I GLONASS and Galileo (multiconstellation functionality)I single frequency processing (low-cost receivers)

VADASE tomorrowI Embedded in a receiver firmware



VADASE and GEO Work Plan (2012-2015)

VADASE and GEO Work Plan (2012-2015)Disasters - C3: Tsunami Early Warning and Hazard Assessment

I The first priority action is devotedI to support tsunami early warning andI to establish an inventory of relevant systems such as the German Indonesian

Tsunami Early Warning System (GITEWS) and the European TsunamiAlerting Device (TAD)

VADASE contributionI VADASE may represent an effective tool for near-field tsunami early

warning, providedI a number of receivers equipped with VADASE algorithm collect GNSS

observation at high-rate (at least 5-10 Hz)I generated displacements and waveforms are used in real-time to estimate a

fault model



VADASE and GEO Work Plan (2012-2015)

Thank you very muchfor your kind attention


g. colosimo, m. crespi, a. mazzoni vadase - a new · pdf filei embedded in a receiver...

Documents