istituto nazionale di geofisica e vulcanologia scientific exploitation of eo data for earthquakes...

Istituto Nazionale di Geofisica e Vulcanologia

SCIENTIFIC EXPLOITATION OF EO DATA FOR EARTHQUAKES AND TECTONICS

Stefano Salvi

National Earthquake CenterIstituto Nazionale di Geofisica e Vulcanologia - Roma

Models for scientific exploitation of EO Data – ESA-ESRIN 11-12 Oct. 2012


1. Processes of the seismic cycle. 2. Earthquake interaction.

3. Earthquake preparation processes.

4. Earthquake-induced hazards.

Some challenges in tectonics and earthquake science


1 – Processes of the seismic cycle

Long term monitoring of crustal strain before and after an earthquake is necessary to understand the large scale processes that bring tectonic stresses to rupture the crust and cause earthquakes, and to understand the rheology of the lower crust and upper mantle.

EO contributing data: SAR , CGPS.

Main requirement: long term monitoring continuity


2 - Earthquake interaction

Temporally dense geodetic time series are needed to investigate the effects of stress redistribution after large earthquakes, and the possible implications for the triggering of large earthquakes on nearby faults.

EO contributing data: SAR, CGPS



The 2010-2011 New Zealand seismic sequence

The Mw 7.1 Darfield mainshock was followed by 5 more Mw > 6 events, occurring during 1.5 years, along an E-W alignment.




Using ENVISAT, ALOS, and COSMO-SkyMed data, and InSAR, and offset tracking techniques, the ground deformation of three of the seismic sources was measured and then modeled.

1 23




The earthquakes had a clear interaction: the first earthquake increased the stress level on the faults of the second earthquake, and together they increased the stress level on the fault of the third event.

1 2 3

Atzori et al., 2012

Main requirement: ad hoc acquisitions on post seismic phase


Monitoring geophysical and geochemical parameters over tectonically active areas in many different geological environments, with high spatial and temporal resolution and accuracy, might unveil important phenomena which are thought to occur during the earthquake preparation phases, at medium to short timescales.

EO contributing data: SAR , CGPS, thermal IR, electromagnetic.

3 - Earthquake preparation processes


During the Emilia seismic sequence, the M 5.9 mainshock was followed, 9 days later, by an M 5.8 aftershock.

We subtracted from a Radarsat interferogram containing the total ground deformation of the two events, a COSMO-SkyMed interferogram containing the deformation due to the second event only.

They have the same LoS.


Deformation transient before the M 5.8 Emilia earthquake

Rsat all eventsCSK 2nd event

- =Courtesy of TRE


We thus obtain the ground deformation occurred just before the second earthquake.

Besides the clear co-seismic pattern of the mainshock, a further deformation pattern become evident (black circle).

There is apparently no comparable size aftershock connected to such signal, which in fact is well explained by foreslip on the same fault plane which later originated the M 5.8 aftershock.


Deformation transient before the M 5.8 Emilia earthquake

=Pezzo et al., 2012

Main requirement: temporally dense monitoring (days)


Earthquake ground shaking and stress transfer may trigger a number of geological effects which increase the co-seismic and post-seismic hazard, e.g. Volcanic eruptions, tsunamis, gravitational sliding, surface faulting and collapse, soil liquefaction, soil gas release, etc.

EO sensors can provide important information to understand the details of some of these effects and their driving processes.

EO contributing data: SAR , CGPS, optical, thermal, electromagnetic.

4 – Earthquake induced hazards


Several such effects are well mapped by the 5 m resolution COSMO interferogram


Local gravitational deformation triggered by L’Aquila eq.



Local gravitational deformation triggered by L’Aquila eq.

~5 cm displacement triggered by the earthquake on ancient slope deformations

AA

BBCC

Major trench zone

A BC

Moro et al., 2011

Main requirement: high spatial resolution data

(and comparable resolution DEM)


1.EO data acquisition

2.EO data access

3.EO data analysis and information retrieval

Some requirements and recommendations for EO data exploitation – Earthquakes and Tectonics


Scientific User’s requirements:

1 - EO data acquisition

1. long term mission continuity2. stable sensor characteristics and acquisition geometries3. community interaction with Agencies for site selection4. flexibility of acquisition geometry for shorter monitoring periods (e.g.

post-seismic phase)5. large swaths and medium resolution (some applications)6. high resolution EO data and DEMs (other applications)


Possible actions:

1 - EO data acquisition

1. Integrated (and cooperative) long term global observation strategy2. Synergetic use of different missions (e.g. to make up for variable

spatial/temporal resolution and coverage gaps)3. Intelligent resource management (different spatial/temporal sampling

can be used on different areas, e.g. InSAR over Emilia vs Dead Sea)

Problems:

1. loss of monitoring continuity (change of sensor/platform)2. conflicting requirements (high/low resolutions)3. conflicting acquisition requests (science/commercial/operation/defense)



2 - EO data access

1. data at no cost2. standard interfaces for data access (across missions)3. standardisation of formats (across missions)4. short access time


Possible actions:

2 - EO data access

1. inter-agency agreements for cost reduction2. direct satellite download3. provide remote processing capability to scientific community (e.g.

GPOD)4. harmonisation of formats and interfaces/procedures for data access

Problems:

1. costly data for some missions2. delays in image availability3. too many different formats4. different data access procedures and interfaces



3 - EO data analysis and information retrieval

1. funding for research projects2. EO results validation3. access to image processing tools4. specific high level knowledge and processing resources


Possible actions:

1. fund permanent training (and mobility) for Earth scientists2. fund high level university education3. provide free knowledge and technical help to the community (remote

processing, help desk on specific applications) 4. issue scientific research calls, also coordinated among different

Agencies5. stimulate community building

Problems:

1. knowledge gap between development of EO technology and Earth scientists (especially in underdeveloped countries)

2. also, shortage of human and technical resources limits the diffusion of EO data use in many disciplines

3. difficult access to validation data for error estimation (either previous EO results or in situ data)

3 - EO data analysis and information retrieval


Thank you for your attention

and a special thank to Gemma Manoni – ASI for the fruitful discussions

istituto nazionale di geofisica e vulcanologia scientific exploitation of eo data for earthquakes...

Documents

earthquake interaction

earthquake science slide

earthquake preparation

emilia earthquake rsat

cgps slide

earthquakeinduced hazards

post seismic phase slide

emilia seismic sequence