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 The 2003, Mw 7.2 Fiordland earthquake, and its near-source aftershock strong motion data

2004 ◽  
Vol 37 (3) ◽  
pp. 139-145
Author(s):  
P. McGinty
Keyword(s):  
New Zealand ◽  
Strong Motion ◽  
Data Set ◽  
Strong Motion Data ◽  
Preliminary Results ◽  
Motion Data ◽  
Magnitude Range ◽  
Source Data ◽  
Peak Ground Accelerations ◽  
Attenuation Models

The 2003 Fiordland earthquake was not only the best ever recorded subduction interface earthquake to occur in New Zealand, it also provided the opportunity to collect near-source strong-motion data produced by its aftershocks covering a wide magnitude range. Near source strong-motion data had been lacking in the New Zealand data set, on which current attenuation models are based. Here the author presents some preliminary results relating recorded peak ground accelerations in the near-source field to current attenuation models. The near-source data from the 2003 Fiordland earthquake sequence has shown that the observed data has a greater magnitude-dependence than that predicted by the current attenuation models. This new data will help to improve current models and will lead to a better understanding of the attenuation process associated with New Zealand subduction interface earthquakes.

scholarly journals Peak ground accelerations recorded in the 1968 Inangahua earthquake and some attenuation implications

1993 ◽  
Vol 26 (3) ◽  
pp. 349-355 ◽  
Author(s):  
David J. Dowrick ◽  
S. Sritharan
Keyword(s):  
New Zealand ◽  
Strong Motion ◽  
Strong Motion Data ◽  
Western Usa ◽  
Motion Data ◽  
Information Gap ◽  
Wide Range ◽  
Peak Ground Accelerations ◽  
Attenuation Models

The Ms 7.4 1968 Inangahua earthquake was the largest New Zealand earthquake to have occurred from 1934 to 1992. The valuable strong motion data obtained on scratchplate acceleroscopes has not previously been adequately described. Filling that information gap, this paper lists the re-evaluated peak ground accelerations and examines their attenuation properties. It is shown that the accelerations from this event are much stronger over a wide range of source distances than those obtained using attenuation models for the western USA. Similar results have been found for a number of more recent New Zealand events in another study.

POSTPARTUM AMENORRHOEA IN RURAL EASTERN UTTAR PRADESH, INDIA

1998 ◽  
Vol 30 (2) ◽  
pp. 227-243
Author(s):  
K. N. S. YADAVA ◽  
S. K. JAIN
Keyword(s):  
Higher Education ◽  
Uttar Pradesh ◽  
Current Status Data ◽  
North India ◽  
Current Status ◽  
Data Sets ◽  
Survival Status ◽  
The Mean ◽  
The Difference ◽  
Using Data

This paper calculates the mean duration of the postpartum amenorrhoea (PPA) and examines its demographic, and socioeconomic correlates in rural north India, using data collected through 'retrospective' (last but one child) as well as 'current status' (last child) reporting of the duration of PPA.The mean duration of PPA was higher in the current status than in the retrospective data;n the difference being statistically significant. However, for the same mothers who gave PPA information in both the data sets, the difference in mean duration of PPA was not statistically significant. The correlates were identical in both the data sets. The current status data were more complete in terms of the coverage, and perhaps less distorted by reporting errors caused by recall lapse.A positive relationship of the mean duration of PPA was found with longer breast-feeding, higher parity and age of mother at the birth of the child, and the survival status of the child. An inverse relationship was found with higher education of a woman, higher education of her husband and higher socioeconomic status of her household, these variables possibly acting as proxies for women's better nutritional status.

Peak horizontal acceleration and velocity from strong-motion records including records from the 1979 imperial valley, California, earthquake

1981 ◽  
Vol 71 (6) ◽  
pp. 2011-2038 ◽  
Author(s):  
William B. Joyner ◽  
David M. Boore
Keyword(s):  
Strong Motion ◽  
Fault Rupture ◽  
Imperial Valley ◽  
Attenuation Relations ◽  
Motion Data ◽  
Horizontal Acceleration ◽  
Anelastic Attenuation ◽  
Distance Dependence ◽  
Peak Horizontal Acceleration

Abstract We have taken advantage of the recent increase in strong-motion data at close distances to derive new attenuation relations for peak horizontal acceleration and velocity. This new analysis uses a magnitude-independent shape, based on geometrical spreading and anelastic attenuation, for the attenuation curve. An innovation in technique is introduced that decouples the determination of the distance dependence of the data from the magnitude dependence. The resulting equations are log A = − 1.02 + 0.249 M − log r − 0.00255 r + 0.26 P r = ( d 2 + 7.3 2 ) 1 / 2 5.0 ≦ M ≦ 7.7 log V = − 0.67 + 0.489 M − log r − 0.00256 r + 0.17 S + 0.22 P r = ( d 2 + 4.0 2 ) 1 / 2 5.3 ≦ M ≦ 7.4 where A is peak horizontal acceleration in g, V is peak horizontal velocity in cm/ sec, M is moment magnitude, d is the closest distance to the surface projection of the fault rupture in km, S takes on the value of zero at rock sites and one at soil sites, and P is zero for 50 percentile values and one for 84 percentile values. We considered a magnitude-dependent shape, but we find no basis for it in the data; we have adopted the magnitude-independent shape because it requires fewer parameters.

Classification of Main Shocks and Aftershocks in the NGA-West2 Database

2014 ◽  
Vol 30 (3) ◽  
pp. 1257-1267 ◽  
Author(s):  
Kathryn E. Wooddell ◽  
Norman A. Abrahamson
Keyword(s):  
Time Window ◽  
Strong Motion ◽  
Data Sets ◽  
Horizontal Distance ◽  
Strong Motion Data ◽  
Motion Data ◽  
Rupture Plane ◽  
Main Shocks ◽  
Short Period ◽  
Surface Projection

Previous studies have found a systematic difference between short-period ground motions from aftershocks and main shocks, but have not used a consistent methodology for classifying earthquakes in strong motion data sets. A method for unambiguously classifying earthquakes in strong motion data sets is developed. The classification is based on the Gardner and Knopoff time window, but with a distance window based on a new distance metric, CRJB, defined as the shortest horizontal distance between the centroid of the surface projection of the potential aftershock rupture plane and the surface projection of the main shock rupture plane. Class 2 earthquakes are earthquakes that have a CRJB distance less than a selected limit and within a time window appropriate for aftershocks. All other earthquakes are classified as Class 1. For maximum CRJB of 0 km and 40 km, 11% and 36% of the earthquakes in the NGA-West2 database are Class 2 events, respectively.

scholarly journals Ormond earthquake liquefaction reconnaissance report

1993 ◽  
Vol 26 (3) ◽  
pp. 312-328 ◽  
Author(s):  
Steven A. Christensen
Keyword(s):  
New Zealand ◽  
Focal Depth ◽  
Strong Motion ◽  
North West ◽  
The North ◽  
Peak Ground Accelerations ◽  
Seismological Observatory

On August 10 1993, at 09h 46m UT an earthquake of magnitude (ML) 6.4 occurred near Ormond, a locality to the north west of Gisbome in the North Island of New Zealand. The epicentre of the event was 38.52°S, 177.93°E, and had a focal depth of 48 km (Seismological Observatory, Institute of Geological and Nuclear Sciences Ltd.). Strong motion accelerographs at two sites on sediment in Gisborne recorded peak ground accelerations of 0.22 g at a distance of 20 km from the epicentre, while at Wairoa (80 km to the SW of the epicentre) 0.05 g was recorded, at Tolaga Bay (30 km to the NE of the epicentre) 0.09 g was measured [Pers. Comn. J. Zhou], and strong motion lasted for 5-10 s. Intensity of MMVI was observed in the Ormond area with pockets of MMVII, the later being based in particular on the presence of liquefaction.

scholarly journals Tropospheric CO vertical profiles deduced from total columns using data assimilation: methodology and validation

2014 ◽  
Vol 7 (9) ◽  
pp. 3035-3057 ◽  
Author(s):  
L. El Amraoui ◽  
J.-L. Attié ◽  
P. Ricaud ◽  
W. A. Lahoz ◽  
A. Piacentini ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Data Sets ◽  
Vertical Profiles ◽  
Night Time ◽  
Chi Square ◽  
Independent Observations ◽  
The Mean ◽  
The Difference ◽  
Using Data ◽  
Total Column

Abstract. This paper presents a validation of a method to derive the vertical profile of carbon monoxide (CO) from its total column using data assimilation. We choose version 3 of MOPITT CO total columns to validate the proposed method. MOPITT products have the advantage of providing both the vertical profiles and the total columns of CO. Furthermore, this version has been extensively validated by comparison with many independent data sets, and has been used in many scientific studies. The first step of the paper consists in the specification of the observation errors based on the chi-square (χ2) test. The observations have been binned according to three types: over land during daytime, over land during night-time, and over sea. Their respective errors using the χ2 metric have been found to be 8, 11 and 7%. In the second step, the CO total columns, with their specified errors, are used within the assimilation system to estimate the vertical profiles. These are compared to the retrieved profiles of MOPITT V3 at global and regional scales. Generally, the two data sets show similar patterns and good agreement at both scales. Nevertheless, total column analyses slightly overestimate CO concentrations compared to MOPITT observations. The mean bias between both data sets is +15 and +12% at 700 and 250 hPa, respectively. In the third step, the assimilation of total column has been compared to the assimilation of MOPITT vertical profiles. The differences between both analyses are very small. In terms longitude–latitude maps, the mean bias between the two data sets is +6 and +8% at the pressure levels 700 and 200 hPa, respectively. In terms of zonal means, the CO distribution is similar for both analyses, with a mean bias which does not exceed 12%. Finally, the two analyses have been validated using independent observations from the aircraft-based MOZAIC program in terms of vertical profiles over eight airports. Over most airports, both analyses agree well with aircraft profiles. For more than 50% of recorded measurements, the difference between the analyses and MOZAIC does not exceed 5 ppbv (parts per billion by volume).

scholarly journals Attenuation of Modified Mercalli intensity in New Zealand earthquakes

1999 ◽  
Vol 32 (2) ◽  
pp. 55-89 ◽  
Author(s):  
D. J. Dowrick ◽  
D. A. Rhoades
Keyword(s):  
New Zealand ◽  
Distance Measures ◽  
Fault Rupture ◽  
Ground Acceleration ◽  
Seismic Region ◽  
Source Distance ◽  
The Mean ◽  
The Difference ◽  
Attenuation Models ◽  
Saturation Effects

The main result of this study is the development of attenuation expressions for Modified Mercalli intensity isoseismals in New Zealand earthquakes, in terms of magnitude Mw and source distance. Attenuation of isoseismal intensities has been modelled in a new 2-dimensional manner, i.e. in terms of three distance measures, i.e. radius a along the strike of the fault rupture, radius b normal to strike, and the mean radius c. Other factors which are included in the modelling are depth, focal mechanism, tectonic type (i.e. crustal, interface or dipping slab), and regional variations. As well as being implied in the source distance, the moderate effect of depth (to increase intensities) is modelled well with a separate linear depth term. Shallow (hc ≤ 60 km) Reverse mechanism events were found to give stronger intensities than Strike-Slip events which in tum were stronger than Normal mechanism events, the difference near source between Reverse and Normal events of Mw 7+ events being about 0.4 intensity units. Attenuation for the Central Volcanic Region and Deep events differs markedly from the Main Seismic Region. No magnitude saturation effects were found. Comparisons are made with some earlier New Zealand intensity models, and local and international peak ground acceleration attenuation models.

Sign in / Sign up

Export Citation Format

Share Document