1
University Of Utah Seismograph Stations The University of Utah R. Burlacu 1 , K. L. Pankow 1 , K. D. Koper 1 , B. W. Stump 2 , and C. Hayward 2 University of Utah Seismograph Stations 1 , Southern Methodist University 2 Integrating Infrasonic Arrays into the Utah Regional Seismic Network The University of Utah Seismograph Stations (UUSS) operates and maintains a regional and urban seismic network of more than 200 seismic stations, providing accurate data and information products for seismic events using modern monitoring methods and technologies. Building upon more than four decades of seismic station infrastructure, maintenance, and technical expertise, UUSS has integrated nine real-time telemetered infrasonic arrays into the regional seismic network for continuous data recording. The Utah region is characterized by a variety of sources that can generate seismo-acoustic energy, including earthquakes and anthropogenic events like coal and mineral mining blasts, highway construction, and rocket motor detonations. We present two examples of acoustic signals generated by a rocket motor detonation and an earthquake recorded by the Utah infrasonic arrays and preliminary modeling results. I Overview II Array Integration and Scientific Motivation Emphasizing cost effectiveness, the array integration allows: sharing existing seismic data telemetry solutions and data acquisition capabilities exchanging infrasonic data with partners, using an established operational system based on Earthworm software (import/export modules) archiving the infrasonic data at the IRIS DMC, using Earthworm waveservers dedicated to both seismic and acoustic data. The deployment of a network of the nine infrasonic arrays was motivated by a scientific interest in exploring various problems including: location of events that only generate acoustic signals generation and propagation of acoustic energy from local to regional distances from events like earthquakes, explosions, and rocket motor detonations (source and path effects) comparison of recorded infrasound data with models based on atmospheric profiles recorded at the time these events occurred characterization and understanding of acoustic-to-seismic and seismic-to-acoustic energy coupling by collocation of acoustic and seismic sensors Map of the network of seismo-acoustic arrays deployed in the Utah region (red triangles). Also shown: earthquakes (small gray circles) recorded by UUSS since 2000, including seismic events induced by underground coal mining in Wasatch Plateau and Book Cliffs coal fields in east-central Utah (gray polygons) and some of the known blast sites (yellow circles: confirmed blasts by mining operators, orange circles: mines that have permits for blasting, and green circles: man-made events with M>3 since 1997, identified by UUSS) Photos from deployment of infrasound arrays LCMT and PSUT. A) southeast element of LCMT. B) instrumentation at LCMT with Q330, Baler, radio, and GPS antenna. C) IML-ST 8 port microphone installed at PSUT. D) Central element of PSUT, left solar-panel, and obscured box are for infrasound instrumentation while right solar panel and barrels are from the collocated seismic station. IV Examples of Recorded Events Example of a rocket motor detonation (the larger ones in 2010 had a yield of ~50,000 lb TNT equivalent) Utah Test and Training Range (UTTR) disposes rocket motors using an open burn/open detonation (OB/OD) method. To avoid public complaints due to elevated noise levels and to comply with the regulatory noise limits, two semi-empirical sound models were developed, Blast Operation Overpressure Model (BOOM) and Sound Intensity Prediction System (SIPS) (McFarland et al., 2005). Both models are based on measured meteorological data and the decision to detonate at a particular day and time is based on the results from the two models. UTTR does not conduct detonations if either model indicates a peak sound level at 30 km from the site of more than 120 dB. In general, these detonations have been carried out between the months of March and October every year, since 1993. One important aspect in predicting acoustic arrivals through raytracing in the “zone-of-silence” is the availability of atmospheric measurements (temperature and wind). During an experiment in 2007, atmospheric profiles have been measured using rawinsondes launched close to the detonation time. A D B C III Array Characteristics (Right) Array responses of the Utah infrasonic arrays (1, 2 and 5 Hz). Layout of the arrays (upper panel), normalized array response in slowness space Sx, Sy (panels 2-4), cross-section across the normalized array response at Sy=0 (panels 5-7) Each infrasonic array, with an aperture of ~150 m, consists of four sensors with one of the elements collocated with a seismic sensor that is part of the Utah regional seismic network. The arrays are equipped with microphones (Chaparral 2, Chap- arral 2.5, or IML ST) and fitted with eight or ten hoses, for noise re- duction. Data recorders (REFTEK 130, Quanterra Q330) are used to digitize data at 100 sps. BGU BRP EPU FSU HWU LCMT NOQ PSUT WMU 120 o W 118 o W 116 o W 114 o W 112 o W 110 o W 36 o N 38 o N 40 o N 42 o N 44 o N 0.26 0.27 0.28 0.29 0.3 0.31 0.32 0.33 0.34 0.35 Vg (km/s) UTTR Rocket Motor Detonations Atmospheric Measurements and Raytracing Implications (Left) Waveforms filtered in 1–5 Hz frequency band and InfraMonitor detection results from processing the acoustic data recorded from the June 28, 2010 UTTR rocket motor detonation. The colored lines represent the expected times for seismic (red, blue and purple) and for epicentral infrasonic arrivals (green) having group velocities between 0.22 and 0.35 km/s, respectively. (Right) Location of the detonation event based on infrasound detections using the Bayesian Infrasound Source Location (BISL) algorithm. Triangles show locations of arrays contributing to the location. The 75, 90, and 95 percent credibility contours are also shown. The ground-truth detonation site is represented by the orange star. (Left) Arrival predictions (color-coded by group velocity) for August 1, 2007 by raytracing using the TauP method, based on the Ground-to-Space (G2S) atmospheric profile. The green star symbol represents the UTTR detonation site and the red inverted triangle is the EarthScope TA station N12A. No arrival is predicted by raytracing at N12A when using only the G2S profile. (Right) Combining the G2S and the measured local atmospheric profiles arrivals at these distances can be predicted. Rays launched from the source (UTTR site) are plotted with the background representing the combined atmospheric profile, expressed as effective speed of sound (m/s) as a function of altitude (km). REFERENCES Arrowsmith, S.J., R. Whitaker, S.R. Taylor, R. Burlacu, B. Stump, M. Hedlin, G. Randall, C. Hayward, and D. ReVelle (2008). Regional monitoring of infrasound events using multiple arrays: application to Utah and Washington State. Geophys. J. Int., 175, 291–300. Arrowsmith, S. J., and R. W. Whitaker (2008), InfraMonitor: A Tool for Regional Infrasound Monitoring, in 30th Monitoring Research Review, edited, Ports- mouth, VA. Drob, D. P., M. Garces, M. A. H. Hedlin, and N. Brachet (2010), The Temporal Morphology of Infrasound Propagation, Pure appl. geophys., doi:10.1007/s00024-010-0080-6. Farland, M.J., G. R. Palmer, M.M. Kordich, D.A. Pollet, J.A. Jensen, and M.H. Lindsay (2005). Field validation of sound mitigation models and air pollutant emission testing in support of missile motor disposal activities, J. Air and Waste Manage. Assoc., 55, 1111–1121. Garces, M. A., R. A. Hansen, and K. G. Lindquist (1998). Traveltimes for infrasonic waves propagating in a stratified atmosphere, Geophys. J. Int. 135, 255- 263. Modrak, R. T., S. J. Arrowsmith, and D. N. Anderson (2010). A Bayesian framework for infrasound location, Geophys. J. Int., 181, doi:10.1111/j.1365- 246X.2010.04499.x. Whidden, K. L, K. L. Pankow and T. Taira (2011). A catalog of regional moment tensors in Utah, Seism. Res. Lett., 82, pp. 295. -600 -500 -400 -300 -200 -100 0 0 20 40 60 80 100 120 Distance [km] Altitude [km] Veff [m/s] 250 300 350 400 450 BGU HWU NOQ BRP FSU WMU ACKNOWLEDGMENTS We would like to thank Paul Roberson for assistance with graphics, Dave Drobeck, Mark Hale, Wesley O’Keefe, and Peter O’Neill for their contribution to the array installations. Dataloggers and materials support are being provided by PASSCAL. The 2010 array installations were completed under the Award No. DE-AR52-08NA28608 Proposal No. BAA09-49. An earthquake of Mw 4.6 occurred on January 3, 2011 at 12:06:37 UTC, within a known seismically active belt along the western side of the Sevier Valley in the Tushar Mountains (in the proximity of the city Circleville, UT). The event was widely felt in the surrounding communities, had a normal faulting mechanism, and a depth constrained, by full moment tensor calculation, between 5 and 9 km. The main shock and 85 aftershocks were recorded by Utah’s regional seismic network. Epicentral infrasound from the main event was detected by six of the nine infrasonic arrays distributed throughout Utah. The January 3, 2011 Mw 4.6 Circleville, Utah Earthquake Event parameters: • Location 38.2473, -112.3398, depth 5.4 km • Mw 4.6, M0=1.06e23 dyne-cm Focal planes • F1 (strike 171, dip 35, slip -138) • F2 (strike 45, dip 67, strike -62) (Left) Map of the earthquake source region: MW 4.6 mainshock (yellow star), 85 after- shocks (filled red circles), and 224 earthquakes (faded red circles) that occurred within 10 km of the mainshock since 1970. Also shown are four focal mechanisms corresponding to the mainshock and three aftershocks, determined by Whidden et al. (2011). (Below) Raytracing using the Tau-P method (Garces et al., 1998; Drob et al., 2010) with the G2S atmospheric profile at the time of the event (left). Rays to infrasonic array BRPU color-coded by group velocity; red triangle shows the array location (right). (Above) Array analysis at array BRPU using InfraMonitor (Arrowsmith and Whitaker, 2008). The normalized waveform from one of the sensors is shown on the bottom panel, with detections shown in gray and the predicted arrival window for epicentral infrasound from the earthquake (origin time = 12:06:37 UTC) denoted by red vertical lines. The upper four panels show (top to bottom): the adaptive F-statistic as a function of time, the corresponding cross-correlation coefficient, the backazimuth (horizontal orange line is the great-circle backazimuth to the seismic epicenter), and the phase velocity. M 3.6 M 4.6 M 3.5 M 3.3 (Left) Location solution of epicentral infrasound estimated using the BISL method (Modrak et al., 2010). Six arrays (yellow triangles) were used in the final solution. Epicentral infrasound was not detected at the other three arrays (red triangles). The 75, 90, and 95 percent location credibility contours are also shown. The solution from the seismic location is represented by the red star. (Right) Parabolic Equation (PE) simulations for all 9 UU infrasound arrays for the main event. The top two rows show simulations for the six arrays that detected the earthquake (yellow triangles on the left), while the bottom row shows simulations for the three arrays that did not detect the earthquake (red triangles on the left). T3-P31

Integrating Infrasonic Arrays into the Utah Regional Seismic … R... · Integrating Infrasonic Arrays into the Utah Regional Seismic Network • The University of Utah Seismograph

  • Upload
    others

  • View
    4

  • Download
    0

Embed Size (px)

Citation preview

Page 1: Integrating Infrasonic Arrays into the Utah Regional Seismic … R... · Integrating Infrasonic Arrays into the Utah Regional Seismic Network • The University of Utah Seismograph

University Of Utah Seismograph StationsThe University of Utah R. Burlacu1, K. L. Pankow1, K. D. Koper1, B. W. Stump2, and C. Hayward2

University of Utah Seismograph Stations1 , Southern Methodist University2

Integrating Infrasonic Arrays into the Utah Regional Seismic Network

• The University of Utah Seismograph Stations (UUSS) operates and maintains a regional and urban seismic network of more than 200 seismic stations, providing accurate data and information products for seismic events using modern monitoring methods and technologies.

• Building upon more than four decades of seismic station infrastructure, maintenance, and technical expertise, UUSS has integrated nine real-time telemetered infrasonic arrays into the regional seismic network for continuous data recording.

• The Utah region is characterized by a variety of sources that can generate seismo-acoustic energy, including earthquakes and anthropogenic events like coal and mineral mining blasts, highway construction, and rocket motor detonations.

• We present two examples of acoustic signals generated by a rocket motor detonation and an earthquake recorded by the Utah infrasonic arrays and preliminary modeling results.

I Overview

II Array Integration and Scientific MotivationEmphasizing cost effectiveness, the array integration allows: • sharing existing seismic data telemetry solutions and data acquisition capabilities• exchanging infrasonic data with partners, using an established operational system based on Earthworm software (import/export modules)• archiving the infrasonic data at the IRIS DMC, using Earthworm waveservers dedicated to both seismic and acoustic data.The deployment of a network of the nine infrasonic arrays was motivated by a scientific interest in exploring various problems including:• location of events that only generate acoustic signals• generation and propagation of acoustic energy from local to regional distances from events like earthquakes, explosions, and rocket motor detonations (source and path effects)• comparison of recorded infrasound data with models based on atmospheric profiles recorded at the time these events occurred• characterization and understanding of acoustic-to-seismic and seismic-to-acoustic energy coupling by collocation of acoustic and seismic sensors

Map of the network of seismo-acoustic arrays deployed in the Utah region (red triangles). Also shown: earthquakes (small gray circles) recorded by UUSS since 2000, including seismic events induced by underground coal mining in Wasatch Plateau and Book Cliffs coal fields in east-central Utah (gray polygons) and some of the known blast sites (yellow circles: confirmed blasts by mining operators, orange circles: mines that have permits for blasting, and green circles: man-made events with M>3 since 1997, identified by UUSS)

Photos from deployment of infrasound arrays LCMT and PSUT. A) southeast element of LCMT. B) instrumentation at LCMT with Q330, Baler, radio, and GPS antenna. C) IML-ST 8 port microphone installed at PSUT. D) Central element of PSUT, left solar-panel, and obscured box are for infrasound instrumentation while right solar panel and barrels are from the collocated seismic station.

IV Examples of Recorded Events

Example of a rocket motor detonation (the larger ones in 2010 had a yield of ~50,000 lb TNT equivalent)

Utah Test and Training Range (UTTR) disposes rocket motors using an open burn/open detonation (OB/OD) method. To avoid public complaints due to elevated noise levels and to comply with the regulatory noise limits, two semi-empirical sound models were developed, Blast Operation Overpressure Model (BOOM) and Sound Intensity Prediction System (SIPS) (McFarland et al., 2005). Both models are based on measured meteorological data and the decision to detonate at a particular day and time is based on the results from the two models. UTTR does not conduct detonations if either model indicates a peak sound level at 30 km from the site of more than 120 dB. In general, these detonations have been carried out between the months of March and October every year, since 1993.

One important aspect in predicting acoustic arrivals through raytracing in the “zone-of-silence” is the availability of atmospheric measurements (temperature and wind). During an experiment in 2007, atmospheric profiles have been measured using rawinsondes launched close to the detonation time.

A

D

B

C

III Array Characteristics

(Right) Array responses of the Utah infrasonic arrays (1, 2 and 5 Hz). Layout of the arrays (upper panel), normalized array response in slowness space Sx, Sy (panels 2-4), cross-section across the normalized array response at Sy=0 (panels 5-7)

• Each infrasonic array, with an aperture of ~150 m, consists of four sensors with one of the elements collocated with a seismic sensor that is part of the Utah regional seismic network.

• The arrays are equipped with microphones (Chaparral 2, Chap-arral 2.5, or IML ST) and fitted with eight or ten hoses, for noise re-duction. Data recorders (REFTEK 130, Quanterra Q330) are used to digitize data at 100 sps.

BGU BRP EPU FSU HWU LCMT NOQ PSUT WMU

120 oW 118 oW 116 oW 114 oW 112 oW 110 oW

36 oN

38 oN

40 oN

42 oN

44 oN

0.26

0.27

0.28

0.29

0.3

0.31

0.32

0.33

0.34

0.35

Vg (km/s)

UTTR Rocket Motor Detonations

Atmospheric Measurements and Raytracing Implications

(Left) Waveforms filtered in 1–5 Hz frequency band and InfraMonitor detection results from processing the acoustic data recorded from the June 28, 2010 UTTR rocket motor detonation. The colored lines represent the expected times for seismic (red, blue and purple) and for epicentral infrasonic arrivals (green) having group velocities between 0.22 and 0.35 km/s, respectively. (Right) Location of the detonation event based on infrasound detections using the Bayesian Infrasound Source Location (BISL) algorithm. Triangles show locations of arrays contributing to the location. The 75, 90, and 95 percent credibility contours are also shown. The ground-truth detonation site is represented by the orange star.

(Left) Arrival predictions (color-coded by group velocity) for August 1, 2007 by raytracing using the TauP method, based on the Ground-to-Space (G2S) atmospheric profile. The green star symbol represents the UTTR detonation site and the red inverted triangle is the EarthScope TA station N12A. No arrival is predicted by raytracing at N12A when using only the G2S profile.(Right) Combining the G2S and the measured local atmospheric profiles arrivals at these distances can be predicted.Rays launched from the source (UTTR site) are plotted with the background representing the combined atmospheric profile, expressed as effective speed of sound (m/s) as a function of altitude (km).

REFERENCESArrowsmith, S.J., R. Whitaker, S.R. Taylor, R. Burlacu, B. Stump, M. Hedlin, G. Randall, C. Hayward, and D. ReVelle (2008). Regional monitoring of infrasound events using multiple arrays: application to Utah and Washington State. Geophys. J. Int., 175, 291–300.

Arrowsmith, S. J., and R. W. Whitaker (2008), InfraMonitor: A Tool for Regional Infrasound Monitoring, in 30th Monitoring Research Review, edited, Ports-mouth, VA.

Drob, D. P., M. Garces, M. A. H. Hedlin, and N. Brachet (2010), The Temporal Morphology of Infrasound Propagation, Pure appl. geophys., doi:10.1007/s00024-010-0080-6.

Farland, M.J., G. R. Palmer, M.M. Kordich, D.A. Pollet, J.A. Jensen, and M.H. Lindsay (2005). Field validation of sound mitigation models and air pollutant emission testing in support of missile motor disposal activities, J. Air and Waste Manage. Assoc., 55, 1111–1121.

Garces, M. A., R. A. Hansen, and K. G. Lindquist (1998). Traveltimes for infrasonic waves propagating in a stratified atmosphere, Geophys. J. Int. 135, 255-263.

Modrak, R. T., S. J. Arrowsmith, and D. N. Anderson (2010). A Bayesian framework for infrasound location, Geophys. J. Int., 181, doi:10.1111/j.1365-246X.2010.04499.x.

Whidden, K. L, K. L. Pankow and T. Taira (2011). A catalog of regional moment tensors in Utah, Seism. Res. Lett., 82, pp. 295.

−600 −500 −400 −300 −200 −100 00

20

40

60

80

100

120

Distance [km]

Alti

tude

[km

]

Ve� [m/s]250 300 350 400 450

BGU

HW

UN

OQ

BRP

FSU

WM

U

ACKNOWLEDGMENTSWe would like to thank Paul Roberson for assistance with graphics, Dave Drobeck, Mark Hale, Wesley O’Keefe, and Peter O’Neill for their contribution to the array installations. Dataloggers and materials support are being provided by PASSCAL. The 2010 array installations were completed under the Award No. DE-AR52-08NA28608 Proposal No. BAA09-49.

An earthquake of Mw 4.6 occurred on January 3, 2011 at 12:06:37 UTC, within a known seismically active belt along the western side of the Sevier Valley in the Tushar Mountains (in the proximity of the city Circleville, UT). The event was widely felt in the surrounding communities, had a normal faulting mechanism, and a depth constrained, by full moment tensor calculation, between 5 and 9 km. The main shock and 85 aftershocks were recorded by Utah’s regional seismic network. Epicentral infrasound from the main event was detected by six of the nine infrasonic arrays distributed throughout Utah.

The January 3, 2011 Mw 4.6 Circleville, Utah Earthquake

Event parameters:• Location 38.2473, -112.3398, depth 5.4 km• Mw 4.6, M0=1.06e23 dyne-cm

Focal planes• F1 (strike 171, dip 35, slip -138)• F2 (strike 45, dip 67, strike -62)

(Left) Map of the earthquake source region: MW 4.6 mainshock (yellow star), 85 after-shocks (filled red circles), and 224 earthquakes (faded red circles) that occurred within 10 km of the mainshock since 1970. Also shown are four focal mechanisms corresponding to the mainshock and three aftershocks, determined by Whidden et al. (2011).

(Below) Raytracing using the Tau-P method (Garces et al., 1998; Drob et al., 2010) with the G2S atmospheric profile at the time of the event (left). Rays to infrasonic array BRPU color-coded by group velocity; red triangle shows the array location (right).

(Above) Array analysis at array BRPU using InfraMonitor (Arrowsmith and Whitaker, 2008). The normalized waveform from one of the sensors is shown on the bottom panel, with detections shown in gray and the predicted arrival window for epicentral infrasound from the earthquake (origin time = 12:06:37 UTC) denoted by red vertical lines. The upper four panels show (top to bottom): the adaptive F-statistic as a function of time, the corresponding cross-correlation coefficient, the backazimuth (horizontal orange line is the great-circle backazimuth to the seismic epicenter), and the phase velocity.

M 3.6

M 4.6

M 3.5

M 3.3

(Left) Location solution of epicentral infrasound estimated using the BISL method (Modrak et al., 2010). Six arrays (yellow triangles) were used in the final solution. Epicentral infrasound was not detected at the other three arrays (red triangles). The 75, 90, and 95 percent location credibility contours are also shown. The solution from the seismic location is represented by the red star.

(Right) Parabolic Equation (PE) simulations for all 9 UU infrasound arrays for the main event. The top two rows show simulations for the six arrays that detected the earthquake (yellow triangles on the left), while the bottom row shows simulations for the three arrays that did not detect the earthquake (red triangles on the left).

T3-P31