Surface Motions on Near-Distance Rock Sites in the 2011 Tohoku-Oki Earthquake

2013 ◽  
Vol 29 (1_suppl) ◽  
pp. 23-35 ◽  
Author(s):  
John G. Anderson
Keyword(s):  
Subduction Zone ◽  
Ground Motions ◽  
Source Parameters ◽  
Strong Motion ◽  
Tohoku Earthquake ◽  
Wide Range ◽  
Subduction Zone Earthquakes

This paper selects several sites intended to represent relatively undistorted rock motions just inland from the faulting in the 2011 Tohoku-oki earthquake. Sites were selected for relatively high values of VS30 and for absence of strong site resonances. At these sites, ground motions at the surface were moderate, with peak accelerations of up to ∼330 cm/s2 and peak velocities up to ∼45 cm/s. Although moderate, these records imply that the strong motion generating area of the Tohoku earthquake was as much as ten times more energetic than the 1985 Michoacan earthquake, for which ground motions on rock were recorded above a strong motion generating area. These results suggest that a wide range of source parameters can occur in subduction zone earthquakes.

Pilot Studies of Seismic Hazard and Risk in North Sulawesi Province, Indonesia

1993 ◽  
Vol 9 (1) ◽  
pp. 97-120
Author(s):  
Paul C. Thenhaus ◽  
Stanley L. Hanson ◽  
Ismet Effendi ◽  
Engkon K. Kertapati ◽  
S. T. Algermissen
Keyword(s):  
Subduction Zone ◽  
Ground Motions ◽  
Soft Soil ◽  
Strong Motion ◽  
The United States ◽  
Worst Case ◽  
Pilot Studies ◽  
Masonry Construction ◽  
North Sulawesi ◽  
Average Annual Loss

Earthquake ground motions in North Sulawesi on soft soil that have a 90 percent probability of not being exceeded in 50 years are estimated to be 0.63 g (63 percent of the acceleration of gravity) at Palu, 0.31 g at Gorontalo, and 0.27 g at Manado. Estimated ground motions for rock conditions for the same probability level and exposure time are 56 percent of those for soft soil. The hazard estimates are obtained from seismic sources that model the earthquake potential to a depth of 100 km beneath northern and central Sulawesi and include the Palu fault zone of western Sulawesi, the North Sulawesi subduction zone, and the southern most segment of the Sangihe subduction zone beneath the Molucca Sea. An attenuation relation based on Japanese strong-motion data and considered appropriate for subduction environments of the western Pacific was used in determination of ground motions. Field investigations following the 18 April 1990 North Sulawesi earthquake (Ms 7.3) established the Modified Mercalli intensity (MMI) distribution throughout Kodya Gorontalo (the mayorial province of Gorontalo). The total number of masonry houses (permanent and semipermanent dwellings) within the MMI V isoseismal was approximated from housing counts obtained from a sampling of 19 villages. From the post-earthquake damage investigation and from comparisons to masonry construction in the United States, a vulnerability curve was constructed for masonry housing in Gorontalo. Assuming an average value for a house of $1,053, total economic loss to masonry housing from the 18 April 1990 earthquake is estimated to be $1,198,578, a loss equivalent to the destruction of 9.6 percent of the masonry dwelling stock of Gorontalo. Simulation of the earthquake history for the past 31 years within 300 km of Gorontalo indicates an average annual loss to masonry housing of $358,609, or $30 on a per house basis. Catastrophe potential (a worst-case loss) for masonry housing in Gorontalo that has a 90 percent probability of not being exceeded in 250 years is estimated to be $3,083,525, a loss equivalent to the destruction of 25 percent of the masonry dwelling stock of Gorontalo.

Ground-Motion Model for Deep Intraslab Subduction Zone Earthquakes of Northeastern India (NEI) and Adjacent Regions

2020 ◽  
Author(s):  
Ricky L. Chhangte ◽  
Tauhidur Rahman ◽  
Ivan G. Wong
Keyword(s):  
Subduction Zone ◽  
Ground Motion ◽  
Strong Motion ◽  
Sensitivity Analyses ◽  
Motion Model ◽  
Strong Motion Data ◽  
Northeastern India ◽  
Motion Data ◽  
Ground Motion Model ◽  
Subduction Zone Earthquakes

ABSTRACT In this study, a ground-motion model (GMM) for deep intraslab subduction zone earthquakes in northeastern India (NEI) and adjacent regions, including portions of Bangladesh, Bhutan, China, Myanmar, and Nepal, is developed. Strong-motion data for deep intraslab earthquakes in NEI are very sparse, so it is not possible to develop a robust empirical GMM; hence, we used the stochastic point-source model to develop a new GMM. The model is based on ground-motion simulations of 36,500 Mw 5–8 earthquakes and epicentral distances of 50–300 km. We used region-specific key seismic parameters, for example, stress parameter, quality factor, and path duration in ground-motion simulation. Sensitivity analyses were also performed to evaluate the bias of each key seismic input parameter. We compared our GMM with the existing strong-motion data and compared our model with those of Lin and Lee (2008), Abrahamson et al. (2016), and Idini et al. (2017), which were developed for intraslab earthquakes based on VS30 and hypocentral depth. Our model gives higher values compared with their GMMs. Both peak ground acceleration and spectral acceleration values are estimated for NEI and adjacent regions intraslab earthquakes.

A Review on Long-Term Evaluation of Occurrence Probability for Subduction-Zone Earthquakes in Eastern Japan

2012 ◽  
Vol 166-169 ◽  
pp. 2190-2196 ◽  
Author(s):  
Zheng Ru Tao ◽  
Xia Xin Tao ◽  
Wei Jiang
Keyword(s):  
Subduction Zone ◽  
Tohoku Earthquake ◽  
Large Earthquake ◽  
Occurrence Probability ◽  
Evaluation Approach ◽  
The Pacific ◽  
Term Evaluation ◽  
Subduction Zone Earthquakes ◽  
Eastern Japan

Evaluation approach of occurrence probability for subduction-zone earthquakes adopted in “National Seismic Hazard Maps for Japan” is reviewed, especially for the area of the 2011 off the Pacific coast of Tohoku Earthquake (2011 Tohoku Earthquake in short). One problem is pointed that the occurrence probability of such a large earthquake cannot be predicted just from seismicity in a region small like Miyagi-ken-Oki area or southern Sanriku-Oki. The whole subduction zone in eastern Japan is suggested to be taken into account with the interaction between the energy released in quakes. Finally, a simple test to predict the next large earthquake in the subduction-zone by means of Artificial Neural Network is presented, and the result for the years of 2008-2018 shows there may be an earthquake with magnitude up to 8.8 in the zone.

scholarly journals New Zealand acceleration response spectrum attenuation relations for crustal and subduction zone earthquakes

2006 ◽  
Vol 39 (1) ◽  
pp. 1-58 ◽  
Author(s):  
Graeme H. McVerry ◽  
John X. Zhao ◽  
Norman A. Abrahamson ◽  
Paul G. Somerville
Keyword(s):  
New Zealand ◽  
Subduction Zone ◽  
Strong Motion ◽  
Response Spectra ◽  
Regression Analyses ◽  
Acceleration Response ◽  
Attenuation Relations ◽  
Volcanic Region ◽  
Crustal Earthquakes ◽  
Subduction Zone Earthquakes

Attenuation relations are presented for peak ground accelerations (pga) and 5% damped acceleration response spectra in New Zealand earthquakes. Expressions are given for both the larger and the geometric mean of two randomly-oriented but orthogonal horizontal components of motion. The relations take account of the different tectonic types of earthquakes in New Zealand, i.e., crustal, subduction interface and dipping slab, and of the different source mechanisms for crustal earthquakes. They also model the faster attenuation of high-frequency earthquake ground motions in the volcanic region than elsewhere. Both the crustal and subduction zone attenuation expressions have been obtained by modifying overseas models for each of these tectonic environments to better match New Zealand data, and to cover site classes that relate directly to those used for seismic design in New Zealand codes. The study used all available data from the New Zealand strong-motion earthquake accelerograph network up to the end of 1995 that satisfied various selection criteria, supplemented by selected data from digital seismographs. The seismographs provided additional records from rock sites, and of motions involving propagation paths through the volcanic region, classes of data that are sparse in records produced by the accelerograph network. The New Zealand strong-motion dataset lacks records in the nearsource region, with only one record from a distance of less than 10 km from the source, and at magnitudes greater than Mw 7.23. The New Zealand data used in the regression analyses ranged in source distance from 6 km to 400 km (the selected cutoff) and in moment magnitude from 5.08 to 7.23 for pga, with the maximum magnitude reducing to 7.09 for response spectra data. The required near-source constraint has been obtained by supplementing the New Zealand dataset with overseas peak ground acceleration data (but not response spectra) recorded at distances less than 10 km from the source. Further near-source constraints were obtained from the overseas attenuation models, in terms of relationships that had to be maintained between various coefficients that control the estimated motions at short distances. Other coefficients were fitted from regression analyses to better match the New Zealand data. The need for different treatment of crustal and subduction zone earthquakes is most apparent when the effects or source mechanism are taken into account. For crustal earthquakes, reverse mechanism events produce the strongest motions, followed by strike-slip and normal events. For subduction zone events, the reverse mechanism interface events have the lowest motions, at least in the period range up to about ls, while the slab events, usually with normal mechanisms, are generally strongest. The attenuation relations presented in this paper have been used in many hazard studies in New Zealand over the last five years. In particular, they have been used in the derivation of the elastic site spectra in the new Standard for earthquake loads in New Zealand, NZS 1170.5:2004.

scholarly journals Simultaneous rupture on conjugate faults during the 2018 Anchorage, Alaska, intraslab earthquake (MW 7.1) inverted from strong-motion waveforms

2020 ◽  
Author(s):  
Yujia Guo ◽  
Ken Miyakoshi ◽  
Masato Tsurugi
Keyword(s):  
Subduction Zone ◽  
Source Parameters ◽  
Source Region ◽  
Rare Event ◽  
Strong Motion ◽  
Great Depth ◽  
North American Plate ◽  
Low Velocity ◽  
Intraslab Earthquake ◽  
Simultaneous Rupture

Abstract An MW 7.1 ~50-km-deep intraslab earthquake within the Pacific/Yakutat slab underlying the North American Plate struck Anchorage, southern Alaska, on November 30, 2018. The ground-motion records very close to the source region of the Anchorage earthquake provide an important opportunity to better understand the source characteristics of intraslab earthquakes in this subduction zone. We estimated the kinematic rupture process during this earthquake using a series of strong-motion waveform (0.05–0.4 Hz) inversions. Our inversions clearly indicate that the Anchorage earthquake was a rare intraslab event with simultaneous rupture on two conjugate faults, which are recognized sometimes for shallow crustal earthquakes but rarely for deep intraslab earthquakes. Interestingly, one of the conjugate faults had low aftershock productivity. This fault extends to great depth and may reflect a deep oceanic Moho or a local low-velocity and high-VP/VS zone within the oceanic mantle. Even though the Anchorage earthquake was a rare event due to the conjugate faults, we found that its kinematic source parameters such as the slip amplitude and large-slip area nearly equal the global averages derived from source scaling relationships for intraslab earthquakes. Because the source parameters comparable to the global averages were also found for another large intraslab earthquake in the subducting Pacific/Yakutat slab, these source parameters are likely an important source characteristic common to this subduction zone.

Empirical Fragility Curves of Buildings in Northern Miyagi Prefecture During the 2011 off the Pacific Coast of Tohoku Earthquake

2016 ◽  
Vol 11 (6) ◽  
pp. 1253-1270 ◽  
Author(s):  
Hao Wu ◽  
◽  
Kazuaki Masaki ◽  
Kojiro Irikura ◽  
Susumu Kurahashi ◽  
...  
Keyword(s):  
Pacific Coast ◽  
Fragility Curves ◽  
Ground Motions ◽  
Strong Motion ◽  
Tohoku Earthquake ◽  
2011 Tohoku Earthquake ◽  
The 2011 Tohoku Earthquake ◽  
Kobe Earthquake ◽  
The Pacific ◽  
Miyagi Prefecture

In this study, empirical fragility curves expressed in terms of relationship between damage ratio indices of buildings and ground motion indices were developed in northern Miyagi prefecture located in near-field areas during the 2011 off the Pacific coast of Tohoku Earthquake. The ground motion indices were evaluated from observed ground motions at strong-motion stations and estimated at sites at which no strong-motion accelerometers were deployed during the mainshock. The ground motions at the non-instrumental sites were estimated using the empirical Green’s function method based on bedrock motions inverted from observed records on surfaces from small events that occurred inside the source fault, transfer functions due to underground velocity structures identified from microtremor H/V spectral ratios, and a short-period source model of the mainshock. The findings indicated that the empirical fragility curves as functions of Japan Meteorological Agency (JMA) instrumental seismic intensity during the 2011 Tohoku Earthquake almost corresponded to those during the 1995 Kobe Earthquake and the seven disastrous earthquakes that occurred between 2003 and 2008. However, the empirical fragility curves as functions of peak ground velocity were the lowest. A possible reason for this is that the response spectra of the ground motions in the period ranging from 1.0 s to 1.5 s were small during the 2011 Tohoku Earthquake. Another reason could be the seismic resistant capacities of buildings in the studied districts involved during the 2011 Tohoku Earthquake exceeded those in the cities affected during the 1995 Kobe Earthquake.

scholarly journals Simultaneous rupture on conjugate faults during the 2018 Anchorage, Alaska, intraslab earthquake (MW 7.1) inverted from strong-motion waveforms

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Yujia Guo ◽  
Ken Miyakoshi ◽  
Masato Tsurugi
Keyword(s):  
Subduction Zone ◽  
Source Parameters ◽  
Source Region ◽  
Rare Event ◽  
Strong Motion ◽  
Great Depth ◽  
North American Plate ◽  
Low Velocity ◽  
Intraslab Earthquake ◽  
Simultaneous Rupture

AbstractAn MW 7.1 ~ 50-km-deep intraslab earthquake within the Pacific/Yakutat slab underlying the North American Plate struck Anchorage, southern Alaska, on November 30, 2018. The ground-motion records very close to the source region of the Anchorage earthquake provide an important opportunity to better understand the source characteristics of intraslab earthquakes in this subduction zone. We estimated the kinematic rupture process during this earthquake using a series of strong-motion waveform (0.05–0.4 Hz) inversions. Our inversions clearly indicate that the Anchorage earthquake was a rare intraslab event with simultaneous rupture on two conjugate faults, which are recognized sometimes for shallow crustal earthquakes but rarely for deep intraslab earthquakes. Interestingly, one of the conjugate faults had low aftershock productivity. This fault extends to great depth and may reflect a deep oceanic Moho or a local low-velocity and high-VP/VS zone within the oceanic mantle. Even though the Anchorage earthquake was a rare event due to the conjugate faults, we found that its kinematic source parameters such as the slip amplitude and large slip area nearly equal the global averages derived from source scaling relationships for intraslab earthquakes. Because the source parameters comparable to the global averages were also found for another large intraslab earthquake in the subducting Pacific/Yakutat slab, these source parameters are likely an important source characteristic common to this subduction zone.

scholarly journals Simultaneous Rupture on Conjugate Faults During the 2018 Anchorage, Alaska, Intraslab Earthquake (MW 7.1) Inverted from Strong-Motion Waveforms

2020 ◽  
Author(s):  
Yujia Guo ◽  
Ken Miyakoshi ◽  
Masato Tsurugi
Keyword(s):  
Subduction Zone ◽  
Ground Motion ◽  
Source Parameters ◽  
Source Region ◽  
Rare Event ◽  
Strong Motion ◽  
North American Plate ◽  
Aftershock Activity ◽  
Intraslab Earthquake ◽  
Simultaneous Rupture

Abstract An MW 7.1 intraslab earthquake within the Pacific/Yakutat slab underlying the North American Plate struck Anchorage, southern Alaska, on November 30, 2018. The ground-motion records very close to the source region of the Anchorage earthquake provide an important opportunity to better understand the source characteristics of intraslab earthquakes in this subduction zone. We estimated the kinematic rupture process during this earthquake using a series of strong-motion waveform (0.05–0.4 Hz) inversions. Our inversions clearly indicate that the Anchorage earthquake was a rare intraslab event with simultaneous rupture on two conjugate faults, which are worldwide recognized sometimes for shallow crustal earthquakes but rarely for deep intraslab earthquakes. Interestingly, one of the conjugate faults is located in a zone that had low aftershock activity. This fault extends to great depth and may reflect a deep oceanic Moho or a local low-velocity and high-VP/VS zone within the oceanic mantle. Even though the Anchorage earthquake was a rare event due to the conjugate faults, we found that its kinematic source parameters were not abnormal compared to the average parameters of global intraslab earthquakes. The normal source parameters suggest that the larger low-frequency (0.33-Hz) ground-motion amplitudes than predicted by the ground-motion prediction equation observed in downtown Anchorage were primarily due to site amplification effects associated with a sedimentary basin, not source effects. Because such normality of the source parameters was also found for another large intraslab earthquake in the subducting Pacific/Yakutat slab, this normality is likely an important source characteristic common to this subduction zone.

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