Implementation of tsunami early warning using earthquake rupture duration
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Implementation of tsunami early warning using earthquake rupture duration. Michelini A. 1 and Lomax, A. 2 1 .Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy, [email protected] 2 . ALomax Scientific, Mouans-Sartoux, France. [email protected] Talk Structure.

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Implementation of tsunami early warning using earthquake rupture duration

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Implementation of tsunami early warning using earthquake rupture duration

Implementation of tsunami early warning using earthquake rupture duration

Michelini A.1 and Lomax, A.2

1.Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy, [email protected]

2.ALomax Scientific, Mouans-Sartoux, France. [email protected]


Talk structure

Talk Structure

  • Problem and earlier work

  • Duration-Exceedance Alarm design and implementation

  • Data

  • Examples movie of tsunami (and non-tsunami) alerts

  • Summary

2009 AGU Fall Meeting

S33D. Research and Development in Nuclear Explosion Monitoring II


Problem and earlier work

Problem and earlier work

  • Rapid tsunami assessmentare critical for rapid alerts and intervention.

  • P-waves can provide very first information on earthquake size and tsunami potential

  • Tsunami Warning centers, depending whether local or regional, rely on earthquake location and magnitude and on pre-determined tsunami scenarios for early warning

    • Effective regional warning requires assessment in < 15’

  • Mwp (Tsuboi et al., 1995) is the quickest methodology at teleseismic distances to determine earthquake size but

    • Accurate up to Mw~7.5

    • Underestimates Mw>7.5 and tsunami earthquakes because it does not account for long duration ruptures (i.e., later pulses on the waveforms indicative of source duration)

2009 AGU Fall Meeting

S33D. Research and Development in Nuclear Explosion Monitoring II


Problem and earlier work 2

Problem and earlier work (2)

  • Duration Magnitudes (e.g., MED, Mwpd, mBc, Mhara) take into account the source duration explicitly, are calibrated against MWCMT and do not saturate

  • Theta (i.e., energy to moment ratio) proposed as indicator of tsunami earthquakes (Newman and Okal, 1998)

  • P-wave duration, To, alone appears to be a reliable indicator of tsunami genesis (Lomax and Michelini, 2009a,b; Bormann and Saul, 2009)

2009 AGU Fall Meeting

S33D. Research and Development in Nuclear Explosion Monitoring II


Implementation of tsunami early warning using earthquake rupture duration

Duration-amplitude processing steps:

12 September 2007,

M8.4 Sumatra

raw, velocity seismogram

Duration

Duration

1.5 Hz, Gaussian-filtered seismogram

T0

T0 estimate: smoothed, velocity-squared envelope

ground-displacement seismogram

Amplitude

M0 estimate: integral of displacement over duration T0 (Mwpd=8.5)

2009 AGU Fall Meeting

S33D. Research and Development in Nuclear Explosion Monitoring II


Tsunamigenic earthquakes rupture duration to 50s to versus mw discriminant

Tsunamigenic earthquakes: rupture duration To > 50s(To versus Mw discriminant)

2009 AGU Fall Meeting

S33D. Research and Development in Nuclear Explosion Monitoring II


Tsunami early warning using duration exceedance

Tsunami Early Warningusing Duration - Exceedance

2006, Mw7.7,

T0=180s, It=18

Indonesia

tsunami earthquake

2009, Mw7.6,

T0=39 s, It=1

Tonga Islands

(from Lomax & Michelini, 2009b; http://s3.rm.ingv.it/D-E.php

2009 AGU Fall Meeting

S33D. Research and Development in Nuclear Explosion Monitoring II


Discrimination of tsunamigenic earthquakes

Discrimination of tsunamigenic earthquakes

2009 AGU Fall Meeting

S33D. Research and Development in Nuclear Explosion Monitoring II


Ims auxiliary seismic network

IMS auxiliary seismic network

2009 AGU Fall Meeting

S33D. Research and Development in Nuclear Explosion Monitoring II


Ims primary seismic network

IMS primary seismic network

2009 AGU Fall Meeting

S33D. Research and Development in Nuclear Explosion Monitoring II


Iris seedlink realtime station subset

IRIS SeedLink-realtime station subset

2009 AGU Fall Meeting

S33D. Research and Development in Nuclear Explosion Monitoring II


D e for september 29 2009 mw 8 2 samoa

D-E for September 29, 2009 Mw=8.2 Samoa

2009 AGU Fall Meeting

S33D. Research and Development in Nuclear Explosion Monitoring II


D e for september 30 2009 mw 7 7 sumatra

D-E for September 30, 2009 Mw=7.7 Sumatra

2009 AGU Fall Meeting

S33D. Research and Development in Nuclear Explosion Monitoring II


Summary

Summary

  • Tsunami warning should rely on different tools in order to issue alerts

  • Real time data at global scale such as those provided through the SeedLink protocol implemented at IRIS can be used for dedicated tsunami warning procedures

  • Duration-Exceedance, D-E, can be used as fast and reliable discriminant of tsunami occurrence

  • D-E is visualized in real-time on the INGV seismic center video-wall and the procedure is available at http://s3.rm.ingv.it/D-E.php

2009 AGU Fall Meeting

S33D. Research and Development in Nuclear Explosion Monitoring II


Acknowledgements

Acknowledgements

  • This work has been funded by the Italian Civil Protection (project INGV-DPC 2007-2009 S3 contract)

  • The data have been obtained from IRIS accessing the realtime DMC SeedLink server

  • The plots are made with GMT (http://gmt.soest.hawaii.edu).

2009 AGU Fall Meeting

S33D. Research and Development in Nuclear Explosion Monitoring II


Problem and earlier work 3

Problem and earlier work (3)

Earliest tsunami warnings:

  • Primarily Magnitude (Mwp) at US tsunami centers (PTWC and WCATWC; T ~ 5-10’)

  • JMA/Japan warnings based on Magnitude and predetermined scenarios (T ≤ 3’)

  • GITEWS/German-Indonesian based on magnitudes (e.g., mB, mBc) alone ( T≤ 5’)

  • Australian Tsunami Warning System based on magnitude (T ≤ 15’)

2009 AGU Fall Meeting

S33D. Research and Development in Nuclear Explosion Monitoring II


To versus mw discriminant

To versus Mw discriminant

2009 AGU Fall Meeting

S33D. Research and Development in Nuclear Explosion Monitoring II


Implementation of tsunami early warning using earthquake rupture duration

  • The duration-amplitude procedure produces rapidly an earthquake moment magnitude Mwpd from P-wave recordings at teleseismic distances (30-90º)

    • Mwpd available within < 20 minutes after OT.

    • For large earthquakes Mwpd (with moment scaling) matches MwCMT typically within ±0.2 magnitude units.

    • Mwpd does not exhibit saturation for the largest events.

    • Mwpd equals or is better than other procedures for rapid moment magnitude determination.

    • Duration, T0, seems to be a robust indicator for tsunamigenic earthquakes (i.e., T0 ≥ 50 s)

    • The Duration-Exceedance proxy to T0, produces rapid estimates (5-10 minutes) for tsunamigenic earthquakes

  • From Lomax and Michelini, 2009a

2009 AGU Fall Meeting

S33D. Research and Development in Nuclear Explosion Monitoring II


Ims auxiliary seismic network1

IMS auxiliary seismic network

2009 AGU Fall Meeting

S33D. Research and Development in Nuclear Explosion Monitoring II


Implementation of tsunami early warning using earthquake rupture duration

Tsunami importance, It, and Duration, T0, for

identification of tsunami earthquakes

It- Tsunami importance based on water height, h, and 0-4 descriptive indices, i, of tsunami effects (deaths, injuries, damage, houses destroyed)

(NOAA/WDC Historical Tsunami Database (NGDC, 2008)

From Lomax and Michelini, GJI, 2009a

2009 AGU Fall Meeting

S33D. Research and Development in Nuclear Explosion Monitoring II


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