Gail M. Atkinson - Academia.edu (original) (raw)
Papers by Gail M. Atkinson
Bulletin of the …, 2008
On 26 September 2003 a megathrust earthquake of M 8.1 occurred at the Kurile trench, Northern Jap... more On 26 September 2003 a megathrust earthquake of M 8.1 occurred at the Kurile trench, Northern Japan. We used accelerograms recorded on more than 300 K-NET stations, ranging in distance from 40 to 500 km, to determine source, attenuation, and site effects for the mainshock and four aftershocks with M 7.3, 6.4, 5.9, and 5.5. The analyses are based on linear regression applied to the Fourier spectra data of each event. The ground-motion attenuation for all the events can be modeled using an assumed geometric spreading coefficient b 1 1:0 with an associated anelastic attenuation model given by an apparent Q 135f 0:76. By using dummy variables in the regression, site amplifications relative to NEHRP C sites are determined for D and E sites. Nonlinear site amplification was investigated for the M 8.1 data but was not significant in determining the overall amplification factors. Fourier spectra data were corrected to a reference near-source distance and site condition (hard rock). The source spectrum for each event was compared to that of the theoretical Brunemodel spectrum, in order to compute seismic moment and stress drop. Seismic moments obtained in this manner agree with those of other studies. Stress drops range from 100 to 200 bars with no apparent dependence on magnitude. The mainshock stress drop was 120 bars. A similar value (100 bars) was calculated for an interface aftershock. Events with the highest stress drops (near 200 bars) may have been in-slab events.
Proceedings of the Indian Academy of Sciences Earth and Planetary Sciences, 2003
We compiled available news and internet accounts of damage and other effects from the 26th Januar... more We compiled available news and internet accounts of damage and other effects from the 26th January, 2001, Bhuj earthquake, and interpreted them to obtain modified Mercalli intensities at over 200 locations throughout the Indian subcontinent. These values are used to map the intensity distribution using a simple mathematical interpolation method. The maps reveal several interesting features. Within the Kachchh region, the most heavily damaged villages are concentrated towards the western edge of the inferred fault, consistent with western directivity. Significant sedimentinduced amplification is also suggested at a number of locations around the Gulf of Kachchh to the south of the epicenter. Away from the Kachchh region intensities were clearly amplified significantly in areas that are along rivers, within deltas, or on coastal alluvium such as mud flats and salt pans. In addition we use fault rupture parameters inferred from teleseismic data to predict shaking intensity at distances of 0-1000 km. We then convert the predicted hard rock ground motion parameters to MMI using a relationship (derived from internet-based intensity surveys) that assigns MMI based on the average effects in a region. The predicted MMIs are typically lower by 1-2 units than those estimated from news accounts. This discrepancy is generally consistent with the expected effect of sediment response, but it could also reflect other factors such as a tendency for media accounts to focus on the most dramatic damage, rather than the average effects. Our modeling results also suggest, however, that the Bhuj earthquake generated more high-frequency shaking than is expected for earthquakes of similar magnitude in California, and may therefore have been especially damaging.
Haddon (1996) proposes a theoretical model for earth- quake source spectra in eastern North Ameri... more Haddon (1996) proposes a theoretical model for earth- quake source spectra in eastern North America (ENA), based on certain assumptions regarding the rupture process. He shows that if ENA earthquakes are characterized by very high rupture velocities and fractional stress drop, then their high-frequency S-wave radiation is strongly enhanced rela- tive to that predicted by the simple Brune (1970) source
Ground-motion models based on the Bmne point-source approximation have an underlying 092 spectrum... more Ground-motion models based on the Bmne point-source approximation have an underlying 092 spectrum, with a single comer frequency. These models over- predict observed spectral amplitudes at low to intermediate frequencies (-0.1 to 2 Hz), for earthquakes with moment magnitudes M of 4 or greater. The empirical spectra of moderate to large events tend to sag at these frequencies, relative to
Seismological Research Letters, 2014
Eos, Transactions American Geophysical Union, 2005
... IN, India; B, Burma; EU, Eurasia; PH, Philippine; OJ, Okinawa-Japan; MTL, Median Tectonic Lin... more ... IN, India; B, Burma; EU, Eurasia; PH, Philippine; OJ, Okinawa-Japan; MTL, Median Tectonic Line. Fig. ... SERGEI PISAREVSKY, Tectonics Special Research Centre, School of Earth and Geographical Sciences, University of Western Australia, Crawley 170 New Edition of the ...
Eos, Transactions American Geophysical Union, 2000
Seismological Research Letters, 2010
Holocene and Late Wisconsin sediments exposed along three rivers in the Charlevoix seismic zone. ... more Holocene and Late Wisconsin sediments exposed along three rivers in the Charlevoix seismic zone. On the basis of their stratigraphic position and radiocarbon age constraints, the liquefaction features are thought to have formed during three or more earthquake episodes centered in Charlevoix during the past 10,000 years, including at least two prehistoric episodes approximately 5,000 and 10,000 years ago. he spatial distribution of liquefaction features coupled with liquefaction potential analysis suggests that the Charlevoix earthquakes were of moment magnitude (M) ≥ 6.2. Liquefaction features have not been found in similar sediments exposed along eight rivers in the Quebec City-Trois Rivieres area, 70 to 150 km from Charlevoix in the St. Lawrence River Valley. he apparent absence of liquefaction features in the Quebec City-Trois Rivieres area suggests that few, if any, large earthquakes have occurred here during the same time period. he geologic record of earthquakes may be incomplete in both areas due to luctuations in Holocene sea level. Nevertheless, the rate of large earthquakes has apparently been much higher in the Charlevoix seismic zone than in adjacent areas of the St. Lawrence for thousands of years. hese indings suggest that seismicity is localized in Charlevoix and that the presence of Iapetan rit faults that underlie the St. Lawrence Valley of southeastern Canada may not, in itself, indicate earthquake potential. hese results may have important implications for other Iapetan rit faults in the eastern United States, as well as seismic source zone characterization and hazard assessment throughout eastern North America.
Seismological Research Letters, 2012
We have developed a composite Canadian seismicity catalog (CCSC) containing seismicity data to 20... more We have developed a composite Canadian seismicity catalog (CCSC) containing seismicity data to 2009. he primary source of information for the CCSC is the seismicity catalog from the Geological Survey of Canada. Location, magnitude, and focal depth parameters are then supplemented by the addition of available complementary data from other sources. For each event, the set of all available magnitude types is compiled, and a preferred conversion to moment magnitude is provided. he CCSC provides a valuable database for earthquake hazard analysis of major Canadian cities.
Seismological Research Letters, 2008
... trends, as discussed by Atkinson and Wald (2007); the mean binned intensities near the source... more ... trends, as discussed by Atkinson and Wald (2007); the mean binned intensities near the source are approximately IV (4). The mean binned intensities were used to infer MMI-based estimates of PGA and PGV by inverting the following equations of Atkinson and Kaka (2007) to ...
Pure and Applied Geophysics, 2014
Natural Hazards, 2010
The aim of this paper is to present earthquake loss estimations for a portion of downtown Ottawa,... more The aim of this paper is to present earthquake loss estimations for a portion of downtown Ottawa, Canada, using the HAZUS-MH (Hazards United States Multi-Hazard) software tool. The assessment is performed for a scenario earthquake of moment magnitude 6.5, at an epicentral distance of 15 km, occurring during business hours. A level 2 HAZUS-MH analysis was performed where the building inventory, microzonation studies, and site-specific ground motion hazard maps (2% exceedence probability in 50 years) were all improved based on local information. All collected data were assembled into a set of standard geodatabases that are compatible with the HAZUS-MH software using a GISspecific procedure. The results indicate that the greatest losses are expected in unreinforced masonry buildings and commercial buildings. Sensitivity studies show that soil classes, the vulnerability of schools, and the spatial scale of loss estimations are also important factors to take into account.
Journal of Earth System Science, 2003
We compiled available news and internet accounts of damage and other effects from the 26th Januar... more We compiled available news and internet accounts of damage and other effects from the 26th January, 2001, Bhuj earthquake, and interpreted them to obtain modified Mercalli intensities at over 200 locations throughout the Indian subcontinent. These values are used to map the intensity distribution using a simple mathematical interpolation method. The maps reveal several interesting features. Within the Kachchh region, the most heavily damaged villages are concentrated towards the western edge of the inferred fault, consistent with western directivity. Significant sedimentinduced amplification is also suggested at a number of locations around the Gulf of Kachchh to the south of the epicenter. Away from the Kachchh region intensities were clearly amplified significantly in areas that are along rivers, within deltas, or on coastal alluvium such as mud flats and salt pans. In addition we use fault rupture parameters inferred from teleseismic data to predict shaking intensity at distances of 0-1000 km. We then convert the predicted hard rock ground motion parameters to MMI using a relationship (derived from internet-based intensity surveys) that assigns MMI based on the average effects in a region. The predicted MMIs are typically lower by 1-2 units than those estimated from news accounts. This discrepancy is generally consistent with the expected effect of sediment response, but it could also reflect other factors such as a tendency for media accounts to focus on the most dramatic damage, rather than the average effects. Our modeling results also suggest, however, that the Bhuj earthquake generated more high-frequency shaking than is expected for earthquakes of similar magnitude in California, and may therefore have been especially damaging.
Earthquake Spectra, 2006
Methodology for Site Classification Estimation Using Strong Ground Motion Data from the Chi-Chi, ... more Methodology for Site Classification Estimation Using Strong Ground Motion Data from the Chi-Chi, Taiwan, Earthquake. [Earthquake Spectra 22, 511 (2006)]. Vietanh Phung, Gail M. Atkinson, M.EERI, David T. Lau, M.EERI. Abstract. ...
Earthquake Spectra, 2008
The data sets, model parameterizations, and results from the five NGA models for shallow crustal ... more The data sets, model parameterizations, and results from the five NGA models for shallow crustal earthquakes in active tectonic regions are compared. A key difference in the data sets is the inclusion or exclusion of aftershocks. A comparison of the median spectral values for strike-slip ...
Canadian Journal of Earth Sciences, 2003
Canadian Journal of Civil Engineering, 2003
Abstract: A new seismic hazard model, the fourth national model for Canada, has been devised by t... more Abstract: A new seismic hazard model, the fourth national model for Canada, has been devised by the Geological Survey of Canada to update Canada's current (1985) seismic hazard maps. The model incorporates new knowledge from recent earthquakes (both Canadian ...
Bulletin of the Seismological Society of America, 2001
Two methods of determining the apparent source spectrum of ground motion are compared for small t... more Two methods of determining the apparent source spectrum of ground motion are compared for small to moderate earthquakes in the Charlevoix Seismic Zone. The first of these methods uses empirical Green's functions (EGF), in which the spectrum of a target mainshock event is divided by the spectrum of a smaller event in the same location. The EGF approach removes the path, site, and instrument effects from the recorded motion by dividing them out, leaving only the source spectrum of the mainshock. The second method estimates the Fourier spectrum of acceleration near the source directly, by dividing the recorded mainshock spectra by the transfer functions representing the effects of instrument response, attenuation (path effects), and site effects.
Bulletin of the Seismological Society of America, 2013
Large megathrust subduction earthquakes generate prolific aftershock sequences which last over an... more Large megathrust subduction earthquakes generate prolific aftershock sequences which last over an extended period of time and affect wide spatial areas. Among those aftershocks, the largest ones can cause additional damage and pose significant risks to population and infrastructure. Therefore, modeling aftershock sequences of large subduction earthquakes is of considerable importance for seismic-hazard assessment and earthquake risk mitigation. It can also play a prominent role in the ground-shaking modeling of major mainshock-aftershock sequences. In this work, we analyze statistical properties of aftershock sequences of large subduction earthquakes worldwide which occurred from 1973 to present, including recent catastrophic events in Sumatra, Chile, and Japan. We use information provided in the National Earthquake Information Center (NEIC) catalog to extract 70 aftershock sequences generated by mainshocks of M 7.0 and above. We construct their temporal decay rates and magnitudefrequency statistics. To model their temporal behavior, we estimate the parameters of the modified Omori law. In the magnitude domain, we model the frequency-magnitude statistics using the Gutenberg-Richter scaling relationship. We also analyze statistically the difference between the magnitude of the mainshock and the corresponding largest aftershock in the sequence and discuss this in terms of Båth's law. One of the main goals of this work is to investigate the variation in parameter values of the above empirical laws with respect to the magnitude of the mainshock. Our main finding indicates that most parameters do not depend on the magnitude of the mainshock. However, they show some variation in values across different subduction settings.
Bulletin of the …, 2008
On 26 September 2003 a megathrust earthquake of M 8.1 occurred at the Kurile trench, Northern Jap... more On 26 September 2003 a megathrust earthquake of M 8.1 occurred at the Kurile trench, Northern Japan. We used accelerograms recorded on more than 300 K-NET stations, ranging in distance from 40 to 500 km, to determine source, attenuation, and site effects for the mainshock and four aftershocks with M 7.3, 6.4, 5.9, and 5.5. The analyses are based on linear regression applied to the Fourier spectra data of each event. The ground-motion attenuation for all the events can be modeled using an assumed geometric spreading coefficient b 1 1:0 with an associated anelastic attenuation model given by an apparent Q 135f 0:76. By using dummy variables in the regression, site amplifications relative to NEHRP C sites are determined for D and E sites. Nonlinear site amplification was investigated for the M 8.1 data but was not significant in determining the overall amplification factors. Fourier spectra data were corrected to a reference near-source distance and site condition (hard rock). The source spectrum for each event was compared to that of the theoretical Brunemodel spectrum, in order to compute seismic moment and stress drop. Seismic moments obtained in this manner agree with those of other studies. Stress drops range from 100 to 200 bars with no apparent dependence on magnitude. The mainshock stress drop was 120 bars. A similar value (100 bars) was calculated for an interface aftershock. Events with the highest stress drops (near 200 bars) may have been in-slab events.
Proceedings of the Indian Academy of Sciences Earth and Planetary Sciences, 2003
We compiled available news and internet accounts of damage and other effects from the 26th Januar... more We compiled available news and internet accounts of damage and other effects from the 26th January, 2001, Bhuj earthquake, and interpreted them to obtain modified Mercalli intensities at over 200 locations throughout the Indian subcontinent. These values are used to map the intensity distribution using a simple mathematical interpolation method. The maps reveal several interesting features. Within the Kachchh region, the most heavily damaged villages are concentrated towards the western edge of the inferred fault, consistent with western directivity. Significant sedimentinduced amplification is also suggested at a number of locations around the Gulf of Kachchh to the south of the epicenter. Away from the Kachchh region intensities were clearly amplified significantly in areas that are along rivers, within deltas, or on coastal alluvium such as mud flats and salt pans. In addition we use fault rupture parameters inferred from teleseismic data to predict shaking intensity at distances of 0-1000 km. We then convert the predicted hard rock ground motion parameters to MMI using a relationship (derived from internet-based intensity surveys) that assigns MMI based on the average effects in a region. The predicted MMIs are typically lower by 1-2 units than those estimated from news accounts. This discrepancy is generally consistent with the expected effect of sediment response, but it could also reflect other factors such as a tendency for media accounts to focus on the most dramatic damage, rather than the average effects. Our modeling results also suggest, however, that the Bhuj earthquake generated more high-frequency shaking than is expected for earthquakes of similar magnitude in California, and may therefore have been especially damaging.
Haddon (1996) proposes a theoretical model for earth- quake source spectra in eastern North Ameri... more Haddon (1996) proposes a theoretical model for earth- quake source spectra in eastern North America (ENA), based on certain assumptions regarding the rupture process. He shows that if ENA earthquakes are characterized by very high rupture velocities and fractional stress drop, then their high-frequency S-wave radiation is strongly enhanced rela- tive to that predicted by the simple Brune (1970) source
Ground-motion models based on the Bmne point-source approximation have an underlying 092 spectrum... more Ground-motion models based on the Bmne point-source approximation have an underlying 092 spectrum, with a single comer frequency. These models over- predict observed spectral amplitudes at low to intermediate frequencies (-0.1 to 2 Hz), for earthquakes with moment magnitudes M of 4 or greater. The empirical spectra of moderate to large events tend to sag at these frequencies, relative to
Seismological Research Letters, 2014
Eos, Transactions American Geophysical Union, 2005
... IN, India; B, Burma; EU, Eurasia; PH, Philippine; OJ, Okinawa-Japan; MTL, Median Tectonic Lin... more ... IN, India; B, Burma; EU, Eurasia; PH, Philippine; OJ, Okinawa-Japan; MTL, Median Tectonic Line. Fig. ... SERGEI PISAREVSKY, Tectonics Special Research Centre, School of Earth and Geographical Sciences, University of Western Australia, Crawley 170 New Edition of the ...
Eos, Transactions American Geophysical Union, 2000
Seismological Research Letters, 2010
Holocene and Late Wisconsin sediments exposed along three rivers in the Charlevoix seismic zone. ... more Holocene and Late Wisconsin sediments exposed along three rivers in the Charlevoix seismic zone. On the basis of their stratigraphic position and radiocarbon age constraints, the liquefaction features are thought to have formed during three or more earthquake episodes centered in Charlevoix during the past 10,000 years, including at least two prehistoric episodes approximately 5,000 and 10,000 years ago. he spatial distribution of liquefaction features coupled with liquefaction potential analysis suggests that the Charlevoix earthquakes were of moment magnitude (M) ≥ 6.2. Liquefaction features have not been found in similar sediments exposed along eight rivers in the Quebec City-Trois Rivieres area, 70 to 150 km from Charlevoix in the St. Lawrence River Valley. he apparent absence of liquefaction features in the Quebec City-Trois Rivieres area suggests that few, if any, large earthquakes have occurred here during the same time period. he geologic record of earthquakes may be incomplete in both areas due to luctuations in Holocene sea level. Nevertheless, the rate of large earthquakes has apparently been much higher in the Charlevoix seismic zone than in adjacent areas of the St. Lawrence for thousands of years. hese indings suggest that seismicity is localized in Charlevoix and that the presence of Iapetan rit faults that underlie the St. Lawrence Valley of southeastern Canada may not, in itself, indicate earthquake potential. hese results may have important implications for other Iapetan rit faults in the eastern United States, as well as seismic source zone characterization and hazard assessment throughout eastern North America.
Seismological Research Letters, 2012
We have developed a composite Canadian seismicity catalog (CCSC) containing seismicity data to 20... more We have developed a composite Canadian seismicity catalog (CCSC) containing seismicity data to 2009. he primary source of information for the CCSC is the seismicity catalog from the Geological Survey of Canada. Location, magnitude, and focal depth parameters are then supplemented by the addition of available complementary data from other sources. For each event, the set of all available magnitude types is compiled, and a preferred conversion to moment magnitude is provided. he CCSC provides a valuable database for earthquake hazard analysis of major Canadian cities.
Seismological Research Letters, 2008
... trends, as discussed by Atkinson and Wald (2007); the mean binned intensities near the source... more ... trends, as discussed by Atkinson and Wald (2007); the mean binned intensities near the source are approximately IV (4). The mean binned intensities were used to infer MMI-based estimates of PGA and PGV by inverting the following equations of Atkinson and Kaka (2007) to ...
Pure and Applied Geophysics, 2014
Natural Hazards, 2010
The aim of this paper is to present earthquake loss estimations for a portion of downtown Ottawa,... more The aim of this paper is to present earthquake loss estimations for a portion of downtown Ottawa, Canada, using the HAZUS-MH (Hazards United States Multi-Hazard) software tool. The assessment is performed for a scenario earthquake of moment magnitude 6.5, at an epicentral distance of 15 km, occurring during business hours. A level 2 HAZUS-MH analysis was performed where the building inventory, microzonation studies, and site-specific ground motion hazard maps (2% exceedence probability in 50 years) were all improved based on local information. All collected data were assembled into a set of standard geodatabases that are compatible with the HAZUS-MH software using a GISspecific procedure. The results indicate that the greatest losses are expected in unreinforced masonry buildings and commercial buildings. Sensitivity studies show that soil classes, the vulnerability of schools, and the spatial scale of loss estimations are also important factors to take into account.
Journal of Earth System Science, 2003
We compiled available news and internet accounts of damage and other effects from the 26th Januar... more We compiled available news and internet accounts of damage and other effects from the 26th January, 2001, Bhuj earthquake, and interpreted them to obtain modified Mercalli intensities at over 200 locations throughout the Indian subcontinent. These values are used to map the intensity distribution using a simple mathematical interpolation method. The maps reveal several interesting features. Within the Kachchh region, the most heavily damaged villages are concentrated towards the western edge of the inferred fault, consistent with western directivity. Significant sedimentinduced amplification is also suggested at a number of locations around the Gulf of Kachchh to the south of the epicenter. Away from the Kachchh region intensities were clearly amplified significantly in areas that are along rivers, within deltas, or on coastal alluvium such as mud flats and salt pans. In addition we use fault rupture parameters inferred from teleseismic data to predict shaking intensity at distances of 0-1000 km. We then convert the predicted hard rock ground motion parameters to MMI using a relationship (derived from internet-based intensity surveys) that assigns MMI based on the average effects in a region. The predicted MMIs are typically lower by 1-2 units than those estimated from news accounts. This discrepancy is generally consistent with the expected effect of sediment response, but it could also reflect other factors such as a tendency for media accounts to focus on the most dramatic damage, rather than the average effects. Our modeling results also suggest, however, that the Bhuj earthquake generated more high-frequency shaking than is expected for earthquakes of similar magnitude in California, and may therefore have been especially damaging.
Earthquake Spectra, 2006
Methodology for Site Classification Estimation Using Strong Ground Motion Data from the Chi-Chi, ... more Methodology for Site Classification Estimation Using Strong Ground Motion Data from the Chi-Chi, Taiwan, Earthquake. [Earthquake Spectra 22, 511 (2006)]. Vietanh Phung, Gail M. Atkinson, M.EERI, David T. Lau, M.EERI. Abstract. ...
Earthquake Spectra, 2008
The data sets, model parameterizations, and results from the five NGA models for shallow crustal ... more The data sets, model parameterizations, and results from the five NGA models for shallow crustal earthquakes in active tectonic regions are compared. A key difference in the data sets is the inclusion or exclusion of aftershocks. A comparison of the median spectral values for strike-slip ...
Canadian Journal of Earth Sciences, 2003
Canadian Journal of Civil Engineering, 2003
Abstract: A new seismic hazard model, the fourth national model for Canada, has been devised by t... more Abstract: A new seismic hazard model, the fourth national model for Canada, has been devised by the Geological Survey of Canada to update Canada's current (1985) seismic hazard maps. The model incorporates new knowledge from recent earthquakes (both Canadian ...
Bulletin of the Seismological Society of America, 2001
Two methods of determining the apparent source spectrum of ground motion are compared for small t... more Two methods of determining the apparent source spectrum of ground motion are compared for small to moderate earthquakes in the Charlevoix Seismic Zone. The first of these methods uses empirical Green's functions (EGF), in which the spectrum of a target mainshock event is divided by the spectrum of a smaller event in the same location. The EGF approach removes the path, site, and instrument effects from the recorded motion by dividing them out, leaving only the source spectrum of the mainshock. The second method estimates the Fourier spectrum of acceleration near the source directly, by dividing the recorded mainshock spectra by the transfer functions representing the effects of instrument response, attenuation (path effects), and site effects.
Bulletin of the Seismological Society of America, 2013
Large megathrust subduction earthquakes generate prolific aftershock sequences which last over an... more Large megathrust subduction earthquakes generate prolific aftershock sequences which last over an extended period of time and affect wide spatial areas. Among those aftershocks, the largest ones can cause additional damage and pose significant risks to population and infrastructure. Therefore, modeling aftershock sequences of large subduction earthquakes is of considerable importance for seismic-hazard assessment and earthquake risk mitigation. It can also play a prominent role in the ground-shaking modeling of major mainshock-aftershock sequences. In this work, we analyze statistical properties of aftershock sequences of large subduction earthquakes worldwide which occurred from 1973 to present, including recent catastrophic events in Sumatra, Chile, and Japan. We use information provided in the National Earthquake Information Center (NEIC) catalog to extract 70 aftershock sequences generated by mainshocks of M 7.0 and above. We construct their temporal decay rates and magnitudefrequency statistics. To model their temporal behavior, we estimate the parameters of the modified Omori law. In the magnitude domain, we model the frequency-magnitude statistics using the Gutenberg-Richter scaling relationship. We also analyze statistically the difference between the magnitude of the mainshock and the corresponding largest aftershock in the sequence and discuss this in terms of Båth's law. One of the main goals of this work is to investigate the variation in parameter values of the above empirical laws with respect to the magnitude of the mainshock. Our main finding indicates that most parameters do not depend on the magnitude of the mainshock. However, they show some variation in values across different subduction settings.