scholarly journals A decade of progress in seismology since the Edgecumbe earthquake

1997 ◽  
Vol 30 (2) ◽  
pp. 163-166
Author(s):  
Euan G. C. Smith
Keyword(s):  
New Zealand ◽  
Site Response ◽  
Active Faults ◽  
Strong Motion ◽  
Historical Seismicity ◽  
Ground Acceleration ◽  
Earthquake Catalogues ◽  
Motion Data ◽  
Moderate Earthquake ◽  
Large Earthquakes

During the decade, the contemporaneous increase in data from moderately large earthquakes in New Zealand (and overseas) and the re-equipping of the New Zealand seismograph and accelerograph networks has seen good progress on several fronts. Earthquakes are now more accurately located and their spatial distribution is better defined. There have been improvements in the various databases used for seismic hazard assessments: active faults, earthquake catalogues, historical seismicity, and strong ground motions. The increase in strong-motion data has enabled the development of better models for Peak Ground Acceleration, and the effect of site conditions on site response, particularly for weak-to-moderate earthquake motions, has been studied in detail.

A Seismic Intensity Survey of the 16 April 2016 Mw 7.8 Pedernales, Ecuador, Earthquake: A Comparison with Strong-Motion Data and Teleseismic Backprojection

2021 ◽  
Author(s):  
Ellen M. Smith ◽  
Walter D. Mooney
Keyword(s):  
Emergency Response ◽  
Strong Motion ◽  
Seismic Intensity ◽  
Peak Ground Velocity ◽  
Ground Acceleration ◽  
Motion Data ◽  
Contour Maps ◽  
Crustal Earthquakes ◽  
Maximum Value ◽  
Large Earthquakes

Abstract We conducted a seismic intensity survey in Ecuador, following the 16 April 2016 Mw 7.8 Pedernales earthquake, to document the level of damage caused by the earthquake. Our modified Mercalli intensities (MMIs) reach a maximum value of VIII along the coast, where single, two, and multistory masonry and concrete designed buildings partially or completely collapsed. The contours of our MMI maps are similar in shape to the contour maps of peak ground acceleration (PGA) and peak ground velocity (PGV). A comparison of our seismic intensities with the recorded PGA and PGV values reveals that our MMI values are lower than predicted by ground-motion intensity conversion equations that are based on shallow crustal earthquakes. The image of the earthquake rupture obtained using teleseismic backprojection at 0.5–2.0 Hz is coincident with the region of maximum MMI, PGA, and PGV values, Thus, rapid calculation of backprojection may be a useful tool for guiding the deployment of emergency response teams following large earthquakes. The most severe damage observed was, primarily, due to a combination of poorly constructed buildings and site conditions.

The magnitude 8.3 June 23 2001 southern Peru earthquake and tsunami

2003 ◽  
Vol 36 (3) ◽  
pp. 189-207
Author(s):  
Mark Stirling ◽  
Robert Langridge ◽  
Rafael Benites ◽  
Hector Aleman
Keyword(s):  
New Zealand ◽  
Active Faults ◽  
Strong Motion ◽  
Maximum Size ◽  
Southeastern Part ◽  
Ground Acceleration ◽  
Epicentral Area ◽  
Southern Peru ◽  
The One ◽  
2001 Southern Peru Earthquake

We present a precis of our reconnaissance trip to the area of the magnitude 8.3 June 23 2001 southern Peru earthquake and tsunami. The trip was undertaken because of the relevance of the event to hazard assessment in New Zealand. It is the best example in nearly 40 years of the maximum-size earthquake that might occur on the Hikurangi subduction zone, an event that is absent from the historical record of New Zealand (since 1840) and therefore of unknown potential in terms of hazard. Despite the great magnitude of this subduction interface earthquake, it produced only "moderately strong" levels of earthquake shaking (peak ground acceleration of 0.3g on alluvium from the one strong motion accelerograph in the earthquake area, and Modified Mercalli Intensity 8 in the epicentral area), and relatively minor ground damage (liquefaction and landslides). It did however produce a large and devastating tsunami. Our comparison of the one accelerograph record and attenuation curves for subduction interface earthquakes shows that the strength of shaking was typical for subduction interface earthquakes. If we apply our observations to New Zealand, they imply that a Hikurangi subduction interface earthquake may be less damaging to built-up areas in the southeastern part of the North Island (e.g. Wellington and Napier/Hastings) than earthquakes on major active faults in the shallow crust. However, the lateral extent of the strongest shaking in a subduction earthquake (300 km for the southern Peru event) and the associated tsunami generation will make the earthquake very significant in the national context.

New Ground Motion to Intensity Conversion Equations (GMICEs) for New Zealand

2020 ◽  
Vol 92 (1) ◽  
pp. 448-459 ◽  
Author(s):  
Jose M. Moratalla ◽  
Tatiana Goded ◽  
David A. Rhoades ◽  
Silvia Canessa ◽  
Matthew C. Gerstenberger
Keyword(s):  
New Zealand ◽  
Ground Motion ◽  
Strong Motion ◽  
Peak Ground Velocity ◽  
Least Squares Regression ◽  
Data Types ◽  
Ground Acceleration ◽  
Hypocentral Distance ◽  
Motion Data ◽  
Recent Earthquakes

Abstract Macroseismic intensities play a key role in the engineering, seismological, and loss modeling communities. However, at present, there is an increasing demand for instrumental data-based loss estimations that require statistical relationships between intensities and strong-motion data. In New Zealand, there was an urgent need to update the ground motion to intensity conversion equation (GMICE) from 2007, developed prior to a large number of recent earthquakes including the 2010–2011 Canterbury and 2016 Kaikōura earthquake sequences. Two main factors now provide us with the opportunity to update New Zealand’s GMICE: (1) recent publication of New Zealand’s Strong-Motion Database, corresponding to 276 New Zealand earthquakes with magnitudes 3.5–7.8 and 4–185 km depths; and (2) recent generation of a community intensity database from GeoNet’s “Felt Classic” (2004–2016) and “Felt Detailed” (2016–2019) questionnaires, corresponding to around 930,000 individual reports. Ground-motion data types analyzed are peak ground velocity (PGV) and peak ground acceleration (PGA). The intensity database contains 67,572 felt reports from 917 earthquakes, with magnitudes 3.5–8.1, and 1797 recordings from 247 strong-motion stations (SMSs), with hypocentral distances of 5–345 km. Different regression analyses were tested, and the bilinear regression of binned mean strong-motion recordings for 0.5 modified Mercalli intensity bins was selected as the most appropriate. Total least squares regression was chosen for reversibility in the conversions. PGV provided the best-fitting results, with lower standard deviations. The influence of hypocentral distance, earthquake magnitude, and the site effects of local geology, represented by the mean shear-wave velocity in the first 30 m depth, on the residuals was also explored. A regional correction factor for New Zealand, suitable for adjustment of global relationships, has also been estimated.

scholarly journals Probabilistic seismic hazard assessment of the Canterbury region, New Zealand

2001 ◽  
Vol 34 (4) ◽  
pp. 318-334 ◽  
Author(s):  
Mark Stirling ◽  
Jarg Pettinga ◽  
Kelvin Berryman ◽  
Mark Yetton
Keyword(s):  
New Zealand ◽  
Seismic Hazard ◽  
Hazard Assessment ◽  
Regional Scale ◽  
Active Faults ◽  
Seismic Hazard Assessment ◽  
Historical Seismicity ◽  
Probabilistic Seismic Hazard Assessment ◽  
Probabilistic Seismic Hazard ◽  
Ground Acceleration

We present the main results of a probabilistic seismic hazard assessment of the Canterbury region recently completed for Environment Canterbury (formerly Canterbury Regional Council). We use the distribution of active faults and the historical record of earthquakes to estimate the levels of earthquake shaking (peak ground acceleration and response spectral accelerations) that can be expected across the Canterbury region with return periods of 150, 475 and 1000 years. The strongest shaking (e.g. 475 year peak ground accelerations of 0.7g or more) can be expected in the west and north to northwest of the Canterbury region, where the greatest concentrations of known active faults and historical seismicity are located. Site-specific analyses of eight towns and cities selected by Environment Canterbury show that Arthur's Pass and Kaikoura are located within these zones of high hazard. In contrast, the centres studied in the Canterbury Plains (Rangiora, Kaiapoi, Christchurch, Ashburton, Temuka and Timaru) are generally located away from the zones of highest hazard. The study represents the first application of recently-developed methods in probabilistic seismic hazard at a regional scale in New Zealand.

Nonlinear Site Effects from the 30 November 2018 Anchorage, Alaska, Earthquake

2021 ◽  
Author(s):  
John D. Thornley ◽  
Utpal Dutta ◽  
John Douglas ◽  
Zhaohui (Joey) Yang
Keyword(s):  
Site Response ◽  
Strong Motion ◽  
North American Plate ◽  
Peak Ground Velocity ◽  
Reference Station ◽  
Earthquake Hazards ◽  
Ground Acceleration ◽  
Nonlinear Site Response ◽  
Generalized Inversion Technique ◽  
Versus Peak

ABSTRACT Anchorage, Alaska, is a natural laboratory for recording strong ground motions from a variety of earthquake sources. The city is situated in a tectonic region that includes the interface and intraslab earthquakes related to the subducting Pacific plate and crustal earthquakes from the upper North American plate. The generalized inversion technique was used with a local rock reference station to develop site response at >20 strong-motion stations in Anchorage. A database of 94 events recorded at these sites from 2005 to 2019 was also compiled and processed to compare their site response with those in the 2018 Mw 7.1 event (main event). The database is divided into three datasets, including 75 events prior to the main event, the main event, and 19 aftershocks. The stations were subdivided into the site classes defined in the National Earthquake Hazards Reduction Program based on estimated average shear-wave velocity in of the upper 30 m (VS30), and site-response results from the datasets were compared. Nonlinear site response was observed at class D and DE sites (VS30 of 215–300 and 150–215  m/s, respectively) but not at class CD and C sites (VS30 of 300–440 and 440–640  m/s, respectively). The relationship of peak ground acceleration versus peak ground velocity divided by VS30 (shear-strain proxy) was shown to further support the observation that sites with lower VS30 experienced nonlinear site response.

Seismic Response of Embankment Dams Based on Recorded Strong-Motion Data in Japan

2019 ◽  
Vol 35 (2) ◽  
pp. 955-976 ◽  
Author(s):  
DongSoon Park ◽  
Tadahiro Kishida
Keyword(s):  
Time Series ◽  
Seismic Response ◽  
Prediction Models ◽  
Strong Motion ◽  
Dynamic Responses ◽  
Design Stage ◽  
Ground Acceleration ◽  
Motion Data ◽  
Embankment Dams ◽  
Strong Motion Database

It is important to investigate strong-motion time series recorded at dams to understand their complex seismic responses. This paper develops a strong-motion database recorded at existing embankment dams and analyzes correlations between dam dynamic responses and ground-motion parameters. The Japan Commission on Large Dams database used here includes 190 recordings at the crests and foundations of 60 dams during 54 earthquakes from 1978 to 2012. Seismic amplifications and fundamental periods from recorded time series were computed and examined by correlation with shaking intensities and dam geometries. The peak ground acceleration (PGA) at the dam crest increases as the PGA at the foundation bedrock increases, but their ratio gradually decreases. The fundamental period broadly increases with the dam height and PGA at the foundation bedrock. The nonlinear dam response becomes more apparent as the PGA at the foundation bedrock becomes >0.2 g. The prediction models of these correlations are proposed for estimating the seismic response of embankment dams, which can inform the preliminary design stage.

scholarly journals Attenuation of peak ground accelerations in some recent New Zealand earthquakes

1993 ◽  
Vol 26 (1) ◽  
pp. 3-13 ◽  
Author(s):  
D. J. Dowrick ◽  
S. Sritharan
Keyword(s):  
New Zealand ◽  
Strong Motion ◽  
Medium Size ◽  
Data Sets ◽  
Fault Rupture ◽  
Motion Data ◽  
Peak Ground Accelerations ◽  
The Mean ◽  
Using Data ◽  
Event Based

The attenuation of peak ground accelerations was studied for eight New Zealand earthquakes which occurred in the period 1987 to 1991. These events were of medium size with moment magnitudes in the range Mw = 5.8 - 6.7, with depth to centroids of the fault rupture ranging from 4 to 60 km. Attenuation of peak ground accelerations was examined for each event, based on the slope distance from the rupture surface to each strong motion data site. The mean regression attenuation curve for each event was compared with those derived by others using data sets from other parts of the world, allowance being made for source mechanism and depth. Excepting the 1988 Te Anau event, the other seven New Zealand events as a set closely match a Japanese model, but give significantly stronger accelerations than those predicted by the models from western USA and Europe.

scholarly journals Variations between Foundation-Level and Free-Field Earthquake Ground Motions

2000 ◽  
Vol 16 (2) ◽  
pp. 511-532 ◽  
Author(s):  
Jonathan P. Stewart
Keyword(s):  
Free Field ◽  
Low Frequency ◽  
Strong Motion ◽  
Dimensionless Frequency ◽  
Spectral Acceleration ◽  
Ground Acceleration ◽  
Attenuation Relations ◽  
Ground Motion Selection ◽  
Motion Data ◽  
Embedded Foundations

Strong motion data from sites having both an instrumented structure and free-field accelerograph are compiled to evaluate the conditions for which foundation recordings provide a reasonably unbiased estimate of free-field motion with minimal uncertainty. Variations between foundation and free-field spectral acceleration are found to correlate well with dimensionless parameters that strongly influence kinematic and inertial soil-structure interaction phenomena such as embedement ratio, dimensionless frequency (i.e., product of radial frequency and foundation radius normalized by soil shear wave velocity), and ratio of structure-to-soil stiffness. Low frequency components of spectral acceleration recorded on shallowly embedded foundations are found to provide good estimates of free-field motion. In contrast, foundation-level peak ground acceleration (both horizontal and vertical) and maximum horizontal velocity, are found to be de-amplified. Implications for ground motion selection procedures employed in attenuation relations are discussed, and specific recommendations are made as to how these procedures could be improved.

Strong-Motion Data from Structural Response Recorders in Indian Earthquakes

2012 ◽  
Vol 28 (1) ◽  
pp. 77-103 ◽  
Author(s):  
Sudhir K. Jain ◽  
A. D. Roshan ◽  
Siddharth Yadav ◽  
Sonam Srivastava ◽  
Prabir C. Basu
Keyword(s):  
Peak Ground Acceleration ◽  
Structural Response ◽  
Time History ◽  
Strong Motion ◽  
Ground Acceleration ◽  
Motion Data ◽  
The Past ◽  
Simple Instrument ◽  
Low Costs ◽  
The 1960S

In the 1960s several hundred structural response recorders (SRR) were installed all over India. An SRR is a simple instrument consisting of six seismoscopes that provide “maximum response” during an earthquake, without providing the time history. In the past earthquakes, these SRRs have provided several hundred records but they have not been effectively utilized for hazard studies because the measurements from these instruments are considered crude. This paper compares the data obtained from SRRs with that from more modern strong-motion accelerographs (SMAs) for four earthquakes in India. It is shown through statistical analysis that the response obtained from the SRRs is comparable to that from the SMAs. A method has been presented for estimating peak ground acceleration (PGA) from SRR data. Thus, it is shown that SRRs can provide a substantial amount of PGA data for attenuation studies. Many countries may find SRRs useful because of the low costs associated with their manufacture and maintenance.

scholarly journals Uncertainties in attenuation relations for New Zealand seismic hazard analysis

1986 ◽  
Vol 19 (1) ◽  
pp. 28-39 ◽  
Author(s):  
G. H. McVerry
Keyword(s):  
New Zealand ◽  
Seismic Hazard ◽  
Hazard Analysis ◽  
Response Spectrum ◽  
Strong Motion ◽  
Seismic Hazard Analysis ◽  
Ground Acceleration ◽  
Attenuation Relations ◽  
Ground Shaking ◽  
Acceleration Data

Probabilistic techniques for seismic hazard analysis have
come into vogue in New Zealand for both the assessment of major projects and the development and review of seismic design codes. However, there are considerable uncertainties in the modelling
 of the strong-motion attenuation, which is necessarily based largely on overseas data. An excellent agreement is obtained between an average 5% damped response spectrum for New Zealand alluvial sites in the 20 to 59 km distance range and 5.4 to 6.0 magnitude class and that given by a Japanese model. Unfortunately, this corresponds to only about half the amplitude levels of 150 year spectra relevant to code design. The much more rapid decay
of ground shaking with distance in New Zealand has led to a considerable modification based on maximum ground acceleration
data from the Inangahua earthquake of the distance-dependence
of the Japanese response spectra model. Less scatter in New Zealand data has resulted in adopting a lower standard deviation for the attenuation model, which is important in reducing the considerable "probabilistic enhancement" of the hazard estimates. Regional differences in attenuation shown by intensities are difficult to resolve from the strong-motion acceleration data, apart from lower accelerations in Fiordland.

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