1 / 19

A. Zollo and RISSC-Lab Research Group* with A.Lomax ( A.Lomax Scientific Software )

Real-Time Estimation of Earthquake Location and Magnitude for Seismic Early Warning in Campania Region, southern Italy. A. Zollo and RISSC-Lab Research Group* with A.Lomax ( A.Lomax Scientific Software ). *.

eliora
Download Presentation

A. Zollo and RISSC-Lab Research Group* with A.Lomax ( A.Lomax Scientific Software )

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Real-Time Estimation of Earthquake Location and Magnitude for Seismic Early Warning in Campania Region, southern Italy A. Zollo and RISSC-Lab Research Group* with A.Lomax (A.Lomax Scientific Software) * is a joint seismological research group between University of Naples - Dept of Physics and INGV – Osservatorio Vesuviano

  2. Work Motivation • Development and testing of a Seismic Early-Warning System for automated risk mitigation actions in Campania Region • Need for robust and reliable real-time estimates of eqk location and magnitude to be obtained in an evolving, continually updated form. • Need to provide with parameter uncertainty variation with time  engineering structural control

  3. Historical Earthquakes 1980 Irpinia earthquake, Ms=6.9

  4. Recent Seismicity Early Warning Network 29 sites Osiris 24-bit Data Logger 6 channels: 3 accelerometers 3 seismometers (Short Period or Broad Band) Real time data analysis INGV catalogue (1981-2002) M2.5

  5. 3-5 s TS target TP first Latency & computation SEW System Peculiarities • Characteristic times: 60 km 1.5 - 3.5 s eqk at 4-16 km depth 16 - 18 s 22 - 24 s 80 km 28 - 30 s 100 km time To • High spatial density : Station spacing < 15 km • Wide-Dynamics: Unsaturated signals up to 1 g

  6. Real-Time Earthquake Location Basic Ideas: • Constraint from “not-yet-triggered” stations • Tracing and crossing Equal Differential Time (EDT) surfaces • Probabilistic estimation of eqk location vs time (Evolutionary Approach)

  7. Real-time Evolutionary Location • When a first station Sn triggers at tn= tnow, we can already place limits on a pdf volume that is likely to contain the hypocenter (Voronoi cell). These limits are given by conditional EDT surfaces on which the P travel time to the first triggering station A is equal to the travel-time to each of the not-yet-triggered stations. • As the current time tnow progresses we gain the additional information that the not-yet-triggered stations can only trigger with tl > tnow • When the second and later stations trigger, we construct standard, true EDT surfaces between each pair of the triggered stations.These EDT surfaces are stacked with the volume defined by the not-yet-triggered stations to form the current hypocentral pdfvolume.

  8. Synthetic Examples Earthquake location probability Earthquake location probability Seconds from first trigger Seconds from earthquake Origin Time Triggered stations

  9. Real-Time Magnitude Estimate Basic Ideas • Use both early P- and S-wave information based on the high density / wide dynamics of the network • Correlate low-pass filtered peak amplitudes with Magnitude in increasing time windows • Regression analysis based on the European strong motion Data-Base (ESD, Ambraseys, 2004)

  10. European Strong Motion Data Base* * Ambraseys et al. (2004) • 207 Events with 4≤MW≤7.4 (Kokaeli,1999) • 376 three-component records • Epicentral distance ≤ 50 km • Low-pass filter: 3 Hz • Magnitude bin: 0.3

  11. Measurement of Peak Amplitude H(t)=NS2(t)+EW2(t) Vertical 2-sec 1-sec Horizontal 3Hz low-pass filtered acceleration at station Bagnoli (1980, Irpinia Eqk, Ms=6.9) – Epicentral Distance: 20 Km

  12. Log(PGDt) vs Magnitude Mean value 2-Weighted Standard Error Single data point P-wave Log(displacement) S-wave magnitude

  13. Active slip area vs M Slip-rate vs M Rupture kinematics Rupture dynamics Dynamic stress drop vs M Rise-time vs M The observed correlation between log(PGXt) and Magnitude would imply that “dynamic stress release” and/or “rise-time” scale with earthquake size in the very early stage of seismic ruptures A possible explanation The “far-field” approximation for displacement (f=3Hz, D> 5-6 km): moment rate

  14. Summary • A high-density, wide-dynamics seismic network is being installed in southern Italy for “regional” early-warning applications • The system will implement a real-time eqk location method based on an evolutionary, probabilistic approach • Early P- and S- signal amplitudes (less the 2 sec from first arrival) correlate with magnitude (4≤Mw≤7.4) as from the analysis of the European Strong Motion Data Base • A combination of magnitude estimations obtained by “early P/S peak amplitudes” and “predominant periods” (Allen & Kanamori,2003) measured at different stations as a function of time may significantly improve the accuracy of the earthquake size estimation in real-time procedures.

  15. The End

  16. Multiple Events • Each time a new pick is available, the algorithm: • Temporarily associates the pick to the current event • Relocates the event • Checks the travel-time RMS for the maximum likelihood hypocenter • If RMS < RMSthresh the pick is definitively associated, otherwise a new event is declared

  17. Vertical Modulus of horizontal components

  18. Kanamori & Rivera, BSSA, 2004 Strong Motion Data De Natale et al., BSSA,1987

  19. Log(PGXt) vs Magnitude displacement velocity acceleration Early P-Wave Early S-Wave

More Related