L’Aquila 2009 Pollino 2010-2013 · Pasquale De Gori e Francesco Pio Lucente. ... - Lucente F.P.,...
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16˚00' 16˚24' 16˚00' 16˚24' 40˚00' 0 5 10 km MMN SALB T0721 T0722 T0723 T0724 T0725 CUC Shmin MMN Temporal Variation INGV - DPC S3-Projetc: Short term earthquake prediction and preparation This research has partially ben- efited from funding provided by the Italian Presidenza del Consiglio dei Ministri - Dipartimento della Pro- tezione Civile (DPC). Scientific papers funded by DPC do not rep- resent its official opinion and poli- cies. The Pollino seismic sequence: Can shear wave anisotropy monitoring help earthquake forecast? Marina Pastori 1 , Davide Piccinini 1 , Paolo De Luca 2 , Lucia Margheriti 1 1-Istituto Nazionale di Geofisica e Vulcanologia 2-Uniiversità di Perugia, Facoltà di Scienze Matematiche Fisiche e Naturali, Corso di Laurea in Attività di Protezione Civile The Pollino seismic sequence: Can shear wave anisotropy monitoring help earthquake forecast? Ringraziamenti: Le stazioni temporanee sono state installate dai gruppi rete mobile INGV di Roma e Grottaminarda in collaborazione con L’Università della Calabria (Margheriti et al 2013) e il German Research Centre for Geoscience (GFZ) (Govoni et al 2013). Per i dati delle stazioni temporanee si ringraziano Aladino Govoni e Milena Moretti, per le letture dei tempi di arrivo delle onde P ed S e per le localizzaioni si ringra- zia il gruppo INGV surfanelpick ed in particolare Pasquale De Gori e Francesco Pio Lucente. References: -Crampin S. and Gao Y.; 2010: Earthquakes can be stress?forecast. Geophys. J. Int., 180, 1124-1127. - Govoni Aladino, Luigi Passarelli, Thomas Braun, Francesco Maccaferri, Milena Moretti, Francesco Pio Lucente, Eleonora Rivalta, Simone Cesca, Sebastian Hainzl, Heiko Woith, Pasquale De Gori, Torsten Dahm, Claudio Chiarabba, Lucia Margheriti (2013). Investigating the origin of seismic swarms. An international project addresses the question gaining insight on the seismicity in the Pollino range (Southern Italy)Eos in press - Lucente F.P., De Gori P.,Margheriti L., Piccinini D., Di Bona M., Chiarabba C. and N. Piana Agostinetti (2010): Temporal variation of seismic velocity and anisotropy before the 2009 Mw 6.3 L'Aquila earthquake, Italy, Geology 10.1130/G31463.1 v. 38 no. 11 p. 1015-1018 - L Margheriti, A Amato, T Braun, G Cecere, C D'Ambrosio, P De Gori, A Delladio, A Gervasi, A Govoni, I Guerra, FP Lucente, M Moretti, G Selvaggi. 2013 Emergenza nell’area del Pollino: le attività della Rete Sis- mica Mobile Rapporti Tecnici INGV 252 - Nur, A. 1972, Dilatancy, pore fl uids, and premonitory variations of travel times: Seismological Society of America Bulletin, v. 78, p. 1217–1222. - Pastori M., Valoroso L., Piccinini D., Wustefield A., Zaccarelli L., Bianco F., Kendall M., Di Stefano R., Chiaraluce L., Di Bucci D., Margheriti L. and Barchi M.(2011) Crustal fracturing field and presence of fluid as revealed by seismic anisotropy: case histories from seismogenic areas in the apennines. BOLLETTINO DI GEOFISICA TEORICA E APPLICATA, ISSN: 0006-6729 - Piccinini D. , Margheriti L. , Chiaraluce L. , Cocco M. (2006). Space and time variation of crustal anisotropy during the 1997 Umbria-Marche, central Italy, seismic sequence. Geophys. Jou. Int.167 1482-1490 DOI: 10.1111/j.1365-246X.2006.03112.x - Piccinin D. , M Pastori, L Margheriti - ANISOMAT+: An automatic tool to retrieve seismic anisotropy from local earthquakes. Computers & Geosciences, 2013 - Scholz, C.H., Sykes, L.R., and Aggarwal, Y.P., 1973, Earthquake prediction: A physical basis: Science, v. 181, p. 803–809, doi: 10.1126/science .181.4102.803. Abstract Abstract Since the late the late ’60s-early ’70s era seismologists started developed theories that included variations of the elastic property of the Earth crust and the state of stress and its evolution crust prior to the oc- currence of a large earthquake. Among the others the theory of the dilatancy (Scholz et al., 1973): when a rock is subject to stress, the rock grains are shifted generating micro-cracks, thus the rock itself in- creases its volume. Inside the fractured rock, fluid saturation and pore pressure play an important role in earthquake nucleation, by modulating the effective stress. Thus measuring the variations of wave speed and of anisotropic parameter in time can be highly informative on how the stress leading to a major fault failure builds up. In 80s and 90s such kind of research on earthquake precursor slowed down and the priority was given to seismic hazard and ground motions studies, which are very important since these are the basis for the building codes in many countries. Today we have dense and sophisticated seismic networks to measure wave-fields characteristics: we archive continuous waveform data recorded at three components broad-band seismometers, we almost routinely obtain high resolution ear- thquake locations. Therefore we are ready to start to systematically look at seismic-wave propagation properties to possibly reveal short-term variations in the elastic properties of the Earth crust. In active fault areas and volcanoes, tectonic stress variation influences fracture field orientation and fluid migration processes, whose evolution with time can be monitored through the measurement of the anisotropic pa- rameters ( Piccinini et al., 2006). Through the study of S waves anisotropy it is therefore potentially possible to measure the presence, migration and state of the fluid in the rock traveled by seismic waves, thus providing a valuable route to understanding the seismogenic phenomena and their precursors (Crampin & Gao, 2010). Variations of anisotropic parameter and of the ratio between the compressional (P-wave) and the shear (S-wave) seismic velocities, the Vp/Vs (Nur, 1972)have been recently observed and measured during the preparatory phase of a major ear- thquake (Lucente et al. 2010). Here we show the anisotropic parameters at station MMN during the Pollinoseismic sequence 2010-2013 L’Aquila 2009 L’Aquila 2009 13˚12' 13˚12' 13˚36' 42°12' 42˚24' 13˚36' 42˚24' CAMP FAGN Gran Sasso Range Paganica Fault FIAM AQU North South East West Fast measuremets 464 Mean Fast Direction 0.005 (s/km) 0.005 (s/km) 0.004 (s/km) 0.007 (s/km) Geo-Structural Leged from EMERGEO Working Group, 2010 S hmin National Seismic Network Horizontal minimum Stress Fast Directions Anisotropic Seismicity dataset km 0 5 10 N Two different representations of the obtained anisotropic results for the L’Aquila area: 1) fast direction rose dia- grams, with petal size proportional to the number of the measurements, along with earthquake epicentres (yellow dots) and main structural features [red lineaments modi- fied from EMERGEO Working group (2010)]; 2) mean fast directions (blue lines) scaled to the normalised delay time computed at each station. From Pastori et al., BGTA 2012. to the Shmin, which strikes about NE-SW. Comparison between time series of VP /VS (ratio between compressional-wave and shear-wave ve- locity) and anisotropy param- eters at AQU. A: VP /VS values at stations AQU. B: Normalized delay time dt (delay time divided by length of S- wave path). C: Azimuth f of fast shear-wave polarization direction. D: Azimuth of shear waves linearly polarized: null directions. On each panel, vertical line represents time occurrence of ML = 4 foreshock; black circles are individual measurements; red circles are mean values; red vertical bars indicate stan- dard deviation of mean; green lines are mean values interpolating functions. Mean values are calculated on run- ning windows of 20 samples with 1 sample step in A and D, and of 5 samples with 1 sample step in B and C. From Lucente et al., Geology 2010. Pollino 2010-2013 Pollino 2010-2013 50 100 30 210 60 240 90 270 120 300 150 330 180 0 Nulls MMN 50 100 30 210 60 240 90 270 120 300 150 330 180 0 Fast MMN Anisotropic parameters for the aftershoks of th M=5 earthquake at the stations in the area over the map of Middle-Late Quaternary extensional fault, (Preliminary version of Broz- zetti et al S1). 1 – blue lines with barbs: normal faults whose present activity is suggested by seismological and paleoseimological data; 2 - Light blue: W-SW and S-SEdipping normal faults; Red: E –NEdipping normal faults. 4: outcrop of Quaternary continental suc- cessions. Parameters are projected at the piecing point of the S ray at half the hypocentral depth. T0721 T0724 T0725 T0723 T0722 MMN 0.00 0.05 0.10 0.15 0.20 DT(s) 0 90 180 270 360 450 540 630 720 810 900 990 1080 1170 1260 1350 julian days 3.6 4.3 3.73.6 5.0 0 20 40 60 80 100 120 140 160 180 Fast direction (degrees) 0 3.6 4.3 3.73.6 5.0 dt_m=0.044 dt_m=0.044 dt_m=0.062 dt_m=0.047 dt_m=0.052 dt_m=0.052 12-10-03/12-10-25 12-09-15/12-10-02 12-05-29/12-09-14 11-11-24/12-05-28 10-01-01/11-11-23 12-10-25/13-03-31 12-05-29/12-09-14 11-11-24/12-05-28 10-01-01/11-11-23 12-10-03/12-10-25 12-09-15/12-10-02 12-10-25/13-03-31 MMN Temporal Variation N S E W MMN N S E W 0721 N S E W 0722 N S E W 0723 We divided dataset into 5 periods, separated by the occurrence of the 2012 strongest events (24/11/2011, 28/05/2012 M=4.3, 14/09/2012 M=3.7, 01/10/2012 M=3.6, 25/10/2012 M=5.0). the anisotropic parameters are shown using stereographic projection: The center of stereographic projection represents the station MMN while the position of the bar represents the backazimuth of the event and the distance from the center is a function of the angle of incidence geometry (the outer circle represent 45 degrees). To understand how the anisotropic param- eters vary spatially we analyzed waveforms recorded at stations installed after the occur- rence of the earthquake of 25 October 2012. The red bars in the center of the stereo- graphic projection represent the average di- rection of the fast measurements at the sta- tions. The average values of ∆t range from 0.05 seconds at MMN to 0.08 seconds at T0723 station. Fast directions range from 108°N at MMN to 156°N at T0722. The Green rose diagrams on the map below are frequency plots representing how fast direc- tions trending NW-SE are prevalent at all stations with a significant number of measures. The black arrow in the figure represents the direction of extension (Shmin) in the area (from GPS data and moment tensor). MMN MMN [email protected] RU 2: Monitoring variations in the mechanical properties of the crust from seismic measurements. P.I. Davide Piccinini INGV Temporal trend of fast directions and delay time at MMN, averaged over time for the period 2010 - 2010. The vertical bars and color chang- esrepresent 6 events with magnitude greater than 3.5 (24/11/2011; 28/05/2012 M = 4.3; 19/08/2012 M = 3.7; 14/09/2012 M = 3.7; 01/10/2012 M = 3.6; 25/10/2012 M = 5.0). The gray circles are the individual measurements, the green lines represent averaged values over 50 measurements. We considered allparameters with cc greater than 0.7 and delay time greater than 0.02s. The averaged trends are obtained using the running average algorithm and an overlap length of SM-1 points. Frequency plots of fast direction for each period are shown in differ- ent colors, the red bar is the average for the period. The colors are the same used in the stereographic projection on MMN on the top. Exception made for station FAGN, the di- rections at the other stations and the total of the measurements (lower inset) are almost perpendicular Stereographic projection of the anisotropic parameters to the sta- tion MMN: each segment is ori- ented along the fast direction and its length is proportional to the delay time. N S E W
Transcript of L’Aquila 2009 Pollino 2010-2013 · Pasquale De Gori e Francesco Pio Lucente. ... - Lucente F.P.,...
16˚00' 16˚24'16˚00' 16˚24'
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S3-Projetc: Short term earthquake prediction
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This research has partially ben-efited from funding provided by the Italian Presidenza del Consiglio dei Ministri - Dipartimento della Pro-tezione Civile (DPC). Scientific papers funded by DPC do not rep-resent its official opinion and poli-cies.
The Pollino seismic sequence: Can shear wave anisotropy monitoring help earthquake forecast?Marina Pastori1, Davide Piccinini1, Paolo De Luca2, Lucia Margheriti1
1-Istituto Nazionale di Geofisica e Vulcanologia2-Uniiversità di Perugia, Facoltà di Scienze Matematiche Fisiche e Naturali, Corso di Laurea in Attività di Protezione Civile
The Pollino seismic sequence: Can shear wave anisotropy monitoring help earthquake forecast?
Ringraziamenti: Le stazioni temporanee sono state installate dai gruppi rete mobile INGV di Roma e Grottaminarda in collaborazione con L’Università della Calabria (Margheriti et al 2013) e il German Research Centre for Geoscience (GFZ) (Govoni et al 2013). Per i dati delle stazioni temporanee si ringraziano Aladino Govoni e Milena Moretti, per le letture dei tempi di arrivo delle onde P ed S e per le localizzaioni si ringra-zia il gruppo INGV surfanelpick ed in particolare Pasquale De Gori e Francesco Pio Lucente.
References:-Crampin S. and Gao Y.; 2010: Earthquakes can be stress?forecast. Geophys. J. Int., 180, 1124-1127.- Govoni Aladino, Luigi Passarelli, Thomas Braun, Francesco Maccaferri, Milena Moretti, Francesco Pio Lucente, Eleonora Rivalta, Simone Cesca, Sebastian Hainzl, Heiko Woith, Pasquale De Gori, Torsten Dahm, Claudio Chiarabba, Lucia Margheriti (2013). Investigating the origin of seismic swarms. An international project addresses the question gaining insight on the seismicity in the Pollino range (Southern Italy)Eos in press- Lucente F.P., De Gori P.,Margheriti L., Piccinini D., Di Bona M., Chiarabba C. and N. Piana Agostinetti (2010): Temporal variation of seismic velocity and anisotropy before the 2009 Mw 6.3 L'Aquila earthquake, Italy, Geology 10.1130/G31463.1 v. 38 no. 11 p. 1015-1018- L Margheriti, A Amato, T Braun, G Cecere, C D'Ambrosio, P De Gori, A Delladio, A Gervasi, A Govoni, I Guerra, FP Lucente, M Moretti, G Selvaggi. 2013 Emergenza nell’area del Pollino: le attività della Rete Sis-mica Mobile Rapporti Tecnici INGV 252- Nur, A. 1972, Dilatancy, pore fl uids, and premonitory variations of travel times: Seismological Society of America Bulletin, v. 78, p. 1217–1222.- Pastori M., Valoroso L., Piccinini D., Wustefield A., Zaccarelli L., Bianco F., Kendall M., Di Stefano R., Chiaraluce L., Di Bucci D., Margheriti L. and Barchi M.(2011) Crustal fracturing field and presence of fluid as revealed by seismic anisotropy: case histories from seismogenic areas in the apennines. BOLLETTINO DI GEOFISICA TEORICA E APPLICATA, ISSN: 0006-6729- Piccinini D. , Margheriti L. , Chiaraluce L. , Cocco M. (2006). Space and time variation of crustal anisotropy during the 1997 Umbria-Marche, central Italy, seismic sequence. Geophys. Jou. Int.167 1482-1490 DOI: 10.1111/j.1365-246X.2006.03112.x - Piccinin D. , M Pastori, L Margheriti - ANISOMAT+: An automatic tool to retrieve seismic anisotropy from local earthquakes. Computers & Geosciences, 2013- Scholz, C.H., Sykes, L.R., and Aggarwal, Y.P., 1973, Earthquake prediction: A physical basis: Science, v. 181, p. 803–809, doi: 10.1126/science .181.4102.803.
AbstractAbstractSince the late the late ’60s-early ’70s era seismologists started developed theories that included variations of the elastic property of the Earth crust and the state of stress and its evolution crust prior to the oc-currence of a large earthquake. Among the others the theory of the dilatancy (Scholz et al., 1973): when a rock is subject to stress, the rock grains are shifted generating micro-cracks, thus the rock itself in-creases its volume. Inside the fractured rock, fluid saturation and pore pressure play an important role in earthquake nucleation, by modulating the effective stress. Thus measuring the variations of wave speed and of anisotropic parameter in time can be highly informative on how the stress leading to a major fault failure builds up.
In 80s and 90s such kind of research on earthquake precursor slowed down and the priority was given to seismic hazard and ground motions studies, which are very important since these are the basis for the building codes in many countries. Today we have dense and sophisticated seismic networks to measure wave-fields characteristics: we archive continuous waveform data recorded at three components broad-band seismometers, we almost routinely obtain high resolution ear-thquake locations. Therefore we are ready to start to systematically look at seismic-wave propagation properties to possibly reveal short-term variations in the elastic properties of the Earth crust. In active fault areas and volcanoes, tectonic stress variation influences fracture field orientation and fluid migration processes, whose evolution with time can be monitored through the measurement of the anisotropic pa- rameters ( Piccinini et al., 2006). Through the study of S waves anisotropy it is therefore potentially possible to measure the presence, migration and state of the fluid in the rock traveled by seismic waves, thus providing a valuable route to understanding the seismogenic phenomena and their precursors (Crampin & Gao, 2010). Variations of anisotropic parameter and of the ratio between the compressional (P-wave) and the shear (S-wave) seismic velocities, the Vp/Vs (Nur, 1972)have been recently observed and measured during the preparatory phase of a major ear-thquake (Lucente et al. 2010). Here we show the anisotropic parameters at station MMN during the Pollinoseismic sequence 2010-2013
L’Aquila 2009L’Aquila 2009 13˚12'13˚12' 13˚36'
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Two different representations of the obtained anisotropic results for the L’Aquila area: 1) fast direction rose dia-grams, with petal size proportional to the number of the measurements, along with earthquake epicentres (yellow dots) and main structural features [red lineaments modi-fied from EMERGEO Working group (2010)]; 2) mean fast directions (blue lines) scaled to the normalised delay time computed at each station. From Pastori et al., BGTA 2012.
to the Shmin, which strikes about NE-SW. Comparison between time series of VP /VS (ratio between compressional-wave and shear-wave ve-locity) and anisotropy param- eters at AQU. A: VP /VS values at stations AQU. B: Normalized delay time dt (delay time divided by length of S- wave path). C: Azimuth f of fast shear-wave polarization direction. D: Azimuth of shear waves linearly polarized: null directions. On each panel, vertical line represents time occurrence of ML = 4 foreshock; black circles are individual measurements; red circles are mean values; red vertical bars indicate stan- dard deviation of mean; green lines are mean values interpolating functions. Mean values are calculated on run-ning windows of 20 samples with 1 sample step in A and D, and of 5 samples with 1 sample step in B and C. From Lucente et al., Geology 2010.
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Anisotropic parameters for the aftershoks of th M=5 earthquake at the stations in the area over the map of Middle-Late Quaternary extensional fault, (Preliminary version of Broz-zetti et al S1). 1 – blue lines with barbs: normal faults whose present activity is suggested by seismological and paleoseimological data; 2 - Light blue: W-SW and S-SEdipping normal faults; Red: E –NEdipping normal faults. 4: outcrop of Quaternary continental suc-cessions. Parameters are projected at the piecing point of the S ray at half the hypocentral depth.
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MMN Temporal Variation
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We divided dataset into 5 periods, separated by the occurrence of the 2012 strongest events (24/11/2011, 28/05/2012 M=4.3, 14/09/2012 M=3.7, 01/10/2012 M=3.6, 25/10/2012 M=5.0). the anisotropic parameters are shown using stereographic projection: The center of stereographic projection represents the station MMN while the position of the bar represents the backazimuth of the event and the distance from the center is a function of the angle of incidence geometry (the outer circle represent 45 degrees).
To understand how the anisotropic param-eters vary spatially we analyzed waveforms recorded at stations installed after the occur-rence of the earthquake of 25 October 2012. The red bars in the center of the stereo-graphic projection represent the average di-rection of the fast measurements at the sta-tions. The average values of ∆t range from 0.05 seconds at MMN to 0.08 seconds at T0723 station. Fast directions range from 108°N at MMN to 156°N at T0722.
The Green rose diagrams on the map below are frequency plots representing how fast direc-tions trending NW-SE are prevalent at all stations with a significant number of measures. The black arrow in the figure represents the direction of extension (Shmin) in the area (from GPS data and moment tensor).
MMNMMN
RU 2: Monitoring variations in the mechanical properties of the crust from seismic measurements. P.I. Davide Piccinini INGV
Temporal trend of fast directions and delay time at MMN, averaged over time for the period 2010 - 2010. The vertical bars and color chang-esrepresent 6 events with magnitude greater than 3.5 (24/11/2011; 28/05/2012 M = 4.3; 19/08/2012 M = 3.7; 14/09/2012 M = 3.7; 01/10/2012 M = 3.6; 25/10/2012 M = 5.0). The gray circles are the individual measurements, the green lines represent averaged values over 50 measurements. We considered allparameters with cc greater than 0.7 and delay time greater than 0.02s. The averaged trends are obtained using the running average algorithm and an overlap length of SM-1 points. Frequency plots of fast direction for each period are shown in differ-ent colors, the red bar is the average for the period. The colors are the same used in the stereographic projection on MMN on the top.
Exception made for station FAGN, the di-rections at the other stations and the total of the measurements (lower inset) are almost perpendicular
Stereographic projection of the anisotropic parameters to the sta-tion MMN: each segment is ori-ented along the fast direction and its length is proportional to the delay time.
N
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