Geographies of uncertainty in the health benefits of air quality improvements

Assessing the long-term benefits of marginal improvements in air quality from regulatory intervention is methodologically challenging. In this study, we explore how the relative risks (RRs) of mortality from air pollution exposure change over time and whether patterns in the RRs can be attributed to air quality improvements. We employed two-stage multilevel Cox models to describe the association between air pollution and mortality for 51 cities with data from the American Cancer Society (ACS) cohort (N = 264,299, deaths = 69,819). New pollution data were computed through models that predict yearly average fine particle (PM_2.5) concentrations throughout the follow-up (1982–2000). Average PM_2.5 concentrations from 1999 to 2000 and sulfate concentrations from 1980 were also examined. We estimated the RRs of mortality associated with air pollution separately for five time periods (1982–1986, 1987–1990, 1991–1994, 1995–1998, and 1999–2000). Mobility models were implemented with a sub-sample of 100,557 subjects to assist with interpreting the RR estimates. Sulfate RRs exhibit a large decline from the 1980s to the 1990s. In contrast, PM_2.5 RRs follow the opposite pattern, with larger RRs later in the 1990s. The reduction in sulfate RR may have resulted from air quality improvements that occurred through the 1980s and 1990s in response to the acid rain control program. PM_2.5 concentrations also declined in many places, but toxic mobile sources are now the largest contributors to PM in urban areas. This may account for the heightened RR of mortality associated with PM_2.5 in the 1990s. The paper concludes with a three alternative explanations for the temporal pattern of RRs, each emphasizing the uncertainty in ascribing health benefits to air quality improvements.     

Health impact assessment of marine emissions in Pearl River Delta region

Global marine vessels emissions are adversely affecting human health particularly in southeast Asia. But health burdens from both ocean- and river-going vessels in Pearl River Delta (PRD) regions are not quantified. We estimated the potential health impacts using pooled relative risks of mortality and hospital admissions in China, and the model derived concentrations of sulfur dioxide (SO₂), particulate matter (PM₁₀), nitrogen dioxide (NO₂) and ozone (O₃) due to vessels emissions. SO₂ concentrations due to marine emissions in Hong Kong were 13.6 μgm^?3 compared with 0.7 μgm^?3 in PRD regions that were far from the marine vessels. In PRD regions, the estimated annual numbers (per million people) of excess deaths from all natural causes and hospital admissions from cardiorespiratory causes attributable to SO₂, NO₂, O₃ and PM₁₀ combined from marine emissions were 45 and 265 respectively. Marine emission control measures could contribute a large reduction in mortality and hospital admissions in PRD regions especially in Hong Kong.     

Vehicle-derived emissions and pollution on the road autovia 2 investigated by rock-magnetic parameters: A case study from Argentina

In this work, we carried out a preliminary study of traffic-derived pollutants from primary sources (vehicles), and on roads (paved area), road borders and surroundings areas. The study is focussed on the identification, distribution and concentration of pollutants and magnetic carriers. Magnetic parameters and their analyses suggest that the magnetic signal of vehicle-derived emissions is controlled by a magnetite-like phase. Magnetic grain size estimations reveal the presence of fine particles (0.1–5 μm) that can be inhaled and therefore are dangerous to human health. Magnetic susceptibility results (about 175 × 10⁻⁵ SI) show a higher magnetic concentration — magnetic enhancement — in the central area of the tollbooth line that is related to higher traffic. In addition, magnetic susceptibility was computed on several roadside soils along a length of 120 km and used to generate a 2-D contour map, which shows higher magnetic values (100–200 10⁻⁵ SI) near the edge of the road. The observed distribution of magnetic values indicates that magnetic particles emitted by vehicles are accumulated and mainly concentrated within a distance of several meters (1–2 m) from the edge of the road. In consequence, the magnetic susceptibility parameter seems to be a suitable indicator of traffic-related pollution. Non-magnetic studies show an enrichment of some trace elements, such as Ba, Cr, Cu, Zn and Pb, that are associated with traffic pollution. Furthermore, statistical correlations between the content of toxic trace metals and magnetic variables support the use of magnetic parameters as potential proxies for traffic-related pollution in this study area.     

Modelling air pollution data by the skew-normal distribution

Particulate matter with an aerodynamic equivalent diameter of up 10 μm is commonly referred to as PM₁₀ and its harmful effects on human health are well known. We model annual means of daily concentrations of PM₁₀ in Italy by the skew-normal distribution, giving theoretical as well as empirical motivations for the model’s choice. Its adequacy is checked through Anderson–Darling statistic. The skew-normal distribution gives a very good fit to the data and it is particularly useful in estimating probabilities of high PM₁₀ concentrations.     

Average mass concentrations of TSP, PM10 and PM2.5 in Erzurum urban atmosphere, Turkey

In this study, particulate matters (TSP, PM₁₀, PM_2.5 and PM_10–2.5) which are hazardous for environment and human health were investigated in Erzurum urban atmosphere at a sampling point from February 2005 to February 2006. During sampling, two low volume samplers were used and each sampling period lasted approximately 24 h. In order for detection of representative sampling region and point of Erzurum, Kriging method was applied to the black smoke concentration data for winter seasons. Mass concentrations of TSP, PM₁₀ and PM_2.5 of Erzurum urban atmosphere were measured on average, as 129, 31 and 13 μg/m³, respectively, in the sampling period. Meteorological factors, such as temperature, wind speed, wind direction and rainfall were typically found to be affecting PMs, especially PM_2.5. Air temperature did not seem to be significantly affecting TSP and PM₁₀ mass concentrations, but had a considerably negative induction on PM_2.5 mass concentrations. However, combustion sourced PM_2.5 was usually diluted from the urban atmosphere by the speed of wind, soil sourced coarse mode particle concentrations (TSP, PM₁₀) were slightly affected by the speed of wind. Rainfall was found to be decreasing concentrations to 48% in all fractions (TSP, PM₁₀, PM_10–2.5, PM_2.5) and played an important role on dilution of the atmosphere. Fine mode fraction of PM (PM_2.5) showed significant daily and seasonal variations on mass concentrations. On the other hand, coarse mode fractions (TSP, PM₁₀ and PM_10–2.5) revealed more steady variations. It was observed that fine mode fraction variations were affected by the heating in residences during winter seasons.     

Injury and Environmental Epidemiology, a converging agenda

Reliance on motor vehicle travel and the internal combustion engine has provided mobility, but the public health costs are substantial: Road deaths, adverse deleterious health effects from air pollution and noise, reduction in physical exercise, and toxic hazards associated with the refining, transport, use and disposal of petrochemicals. For traumatic road injury, kinetic energy is the pathogen. Risks for injury and death rise with the second and fourth power of increases in velocity upon impact; emissions of many air pollutants also increase exponentially with speed. Models derived from vector transmission in infectious diseases have proven useful for defining risks and designing interventive strategies. These models predict the number of lives saved and injuries prevented from a package of low-cost, effective measures, which can be quickly implemented. Eradication of road deaths and elimination of air pollution emissions are achievable public health goals. Speed camera systems produce sustainable levels of detection deterring speeding, and thereby reducing human injury and environmental damage. “Education” and building more roads, part of the scenario “predict and provide,” have not been shown to reduce injury risks. Building more roads, which in the long run, promotes urban sprawl and congestion, does not reduce travel time. High speed toll roads and circular beltways, which involve trade-offs among time-saving, risk of injury, and diversion of traffic from population centers, need to be re-evaluated and compared to alternative strategies based on modal shifts. We suggest that revenues resulting from massive use of speed cameras can serve as the first step for funding the first steps of sustainable transportation policies based on developing alternatives to private vehicle use and trucking. Such alternatives could lead to even further reductions in injury and death and adverse effects of air pollution. More involvement by epidemiologists in overseeing and evaluating strategies can expedite progress towards the goal of eradication of deaths from road injury, and at the same time, reduce emissions of air pollutants. This revised version was published online in July 2006 with corrections to the Cover Date.     

Horizontal and vertical fluxes of particulate matter during wind erosion on arable land in the province La Pampa,Argentina

A detailed analysis of horizontal and vertical particulate matter (PM) fluxes during wind erosion has been done, based on measurements of PM smaller than 10, 2.5, and 1.0 μm, at windward and leeward positions on a measuring field. The three fractions of PM measurement are differently influenced by the increasing wind and shear velocities of the wind. The measured concentrations of the coarser fractions of the fine dust, PM₁₀, and PM_2.5, increase with wind and shear velocity, whereas the PM_1.0 concentrations show no clear correlation to the shear velocity. The share of PM_2.5 on PM₁₀ depends on the measurement height and wind speed and varies between 4 and 12 m/s at the 1 m height ranging from 25% to 7% (average 10%), and at the 4 m height from 39% to 23% (average 30%). Although general relationships between wind speed, PM concentration, and horizontal and vertical fluxes could be found, the contribution of the measuring field was very low, as balances of incoming and outgoing fluxes show. Consequently, the measured PM concentrations are determined from a variety of sources, such as traffic on unpaved roads, cattle drives, tillage operations, and wind erosion, and thus, represent all components of land use and landscape structure in the near and far surroundings of the measuring field. The current results may reflect factors from the landscape scale rather than the influence of field-related variables. The measuring devices used to monitor PM concentrations showed differences of up to 20%, which led to considerable deviations when determining total balances. Differences up to 67% between the calculated fluxes prove the necessity of a previous calibration of the devices used.     

Correlation between plasmid DNA damage induced by PM10 and trace metals in inhalable particulate matters in Beijing air

Based on the study of Beijing PM₁₀ bioreactivity with the newly developed plasmid DNA assay method, and analysis for trace elements of PM₁₀, the cause of plasmid DNA damage by PM₁₀ was investigated. The study showed that plasmid DNA oxidative damages by PM₁₀ are of difference in different seasons at various areas. The concentrations of TM50 of PM₁₀ in whole samples respectively collected at urban and comparison sites during winter were 900 μg mL⁻¹ and 74 μg mL⁻¹, while those in their corresponding soluble fractions were 540 μg mL⁻¹ and 86 μg mL⁻¹. In contrast, TM50 contents of PM₁₀ from summer whole samples at urban areas and comparison sites were 116 μg mL⁻¹ and 210 μg mL⁻¹, whereas those in their soluble fractions were 180 μg mL⁻¹ and 306 μg mL⁻¹. The difference of bioreactivity of Beijing PM₁₀ resulted from the variation of trace elements. The oxidative damage of plasmid DNA caused by Pb, Zn, As in PM₁₀ (whole sample) was relatively strong. TM50 and Mn, V, Zn display stronger correlation in the soluble fraction. It implies that Zn could be the major trace element in Beijing PM₁₀ which contributes to oxidative damage to plasmid DNA.     

Predicting spatio-temporal concentrations of PM<Subscript>2.5</Subscript> using land use and meteorological data in Yangtze River Delta,China

The prediction of PM_2.5 concentrations with high spatiotemporal resolution has been suggested as a potential method for data collection to assess the health effects of exposure. This work predicted the weekly average PM_2.5 concentrations in the Yangtze River Delta, China, by using a spatio-temporal model. Integrating land use data, including the areas of cultivated land, construction land, and forest land, and meteorological data, including precipitation, air pressure, relative humidity, temperature, and wind speed, we used the model to estimate the weekly average PM_2.5 concentrations. We validated the estimated effects by using the cross-validated R² and Root mean square error (RMSE); the results showed that the model performed well in capturing the spatiotemporal variability of PM_2.5 concentration, with a reasonably large R² of 0.86 and a small RMSE of 8.15 (μg/m³). In addition, the predicted values covered 94% of the observed data at the 95% confidence interval. This work provided a dataset of PM_2.5 concentration predictions with a spatiotemporal resolution of 3 km × week, which would contribute to accurately assessing the potential health effects of air pollution.     

Estimation of the PM2.5 effective hygroscopic parameter and water content based on particle chemical composition: Methodology and case study

Particle hygroscopicity plays a key role in understanding the mechanisms of haze formation and particle optical properties. The present study developed a method for predicting the effective hygroscopic parameter k and the water content of PM_(2.5) on the basis of the k-K?hler theory and bulk chemical components of PM_(2.5). Our study demonstrated that the effective hygroscopic parameter can be estimated using the PM_(2.5) mass concentration, water-soluble ions, and total water-soluble carbon. By combining the estimated k and ambient relative humidity, the water content of PM_(2.5) can be further estimated. As an example, the k and water content of PM_(2.5) in Beijing were estimated utilizing the method proposed in this study. The annual average value of k of PM_(2.5) in Beijing was 0.25±0.09, the maximum k value 0.26±0.08 appeared in summer, and the seasonal variation is insignificant. The PM_(2.5) water content was determined by both the PM_(2.5) hygroscopicity and the ambient relative humidity(RH). The annual average mass ratio of water content and PM_(2.5) was 0.18±0.20, and the maximum value 0.31±0.25 appeared in summer. Based on the estimated water content of PM_(2.5) in Beijing, the relationship between the PM_(2.5) water content and RH was parameterized as: m(%)=0.03+(5.73×10~(-8)) ×RH~(3.72).This parametric formula helps to characterize the relationship between the PM_(2.5) mass concentration and atmospheric visibility.     

Certainty, uncertainty, and the spatiality of disease: a West Nile Virus example

The problem is not uncertainty—proposed here as an inevitable condition—but the chimera of certainty asserted by most contemporary researchers. Problems of data definition, collection, and their use are reviewed in terms of spatial epidemiology and health data with examples drawn from several areas of contemporary health research. The argument is that preconceptions limit data modeled in a manner assuming its completeness. The result, as the West Nile Virus example seeks to demonstrate, may obscure other patterns and limit avenues of research.     

Investigation of hot Flow Anomaly structure observed near the Earth’s bow shock

The work is dedicated to investigation of Hot Flow Anomaly (HFA), formed at the front of Earth’s bows hock. Using Interball-Tail data we estimated orientation of the current sheet that was a cause of the anomaly. From the ion energy-time spectrogram we divided the anomaly into several regions. The motional electric fields near the HFA were estimated with 3D model of Earth’s bow shock. In accordance with previous investigations of HFA’s formation conditions these fields were directed towards the current sheet on both sides of it. We also provided the picture of HFA’s motion along the bow shock and calculated its speed. Analyzing ions’ bulk velocities within the HFA we found that the anomaly is expanding. This conclusion was supported by estimation of thermal and magnetic pressure balance. Ion energy-time spectrogram shows that anomaly is a complicated structure consisting of two parts—leading and trailing. Comparison of ion velocity distributions, magnetic field data and ion energy-time spectrogram provides better understanding of the phenomena and indicated the region that is the source of thermal and convective energy inside HFA.     

Bathing water quality monitoring of Varna Black Sea coastal zone,Bulgaria

Physicochemical and microbiological characteristics of the bathing waters in Varna’s Black Sea coastal area were investigated during year 2007 at 23 monitoring stations. Most of the determined physicochemical parameters—pH, mineral oils, surface active substances, phenols, dissolved oxygen, nutrients and microbiological parameters—“Total coliforms”, “Faecal coliforms”, “Faecal streptococci” were in compliance with the guidline’ limits and exhibited good water quality. Ammonium and phosphate’s pollution above the limits was determined at the South beach, Officers beach and Central beach situated in Varna’s central bathing zone. For the period of 13.08 to 24.10.2007—70% of the South beach samples analyzed for NH₄⁺ exceeded the limits 60 times and the concentrations of PO₄³⁻ exceeded the limits 17.5 times. Some deviations from the guidline’ limits regarding the microbiology were exhibited at the same beaches. A conclusion is made that the area of study is not yet seriously threatened, in spite of the rapid recreation during the last years.     

Site effect assessment using KiK-net data: part 2—site amplification prediction equation based on f<Subscript>0</Subscript> and Vsz

This paper presents empirical correlations between amplification factors and simple site parameters derived from a large subset of the KiK-net data. The amplification factor is estimated from the ratios between the surface and down-hole horizontal response spectra, corrected for the varying depths and impedance of the down-hole sites (Cadet et al. in Site effect assessment using KiK-net data—part 1—a simple correction procedure for surface/downhole spectral ratios, 2011). Several site parameters are selected on the basis of their simplicity and availability at relatively low cost. They are the shallow time-average velocities V_SZ, with z equal to 5, 10, 20 and 30 m, and the fundamental frequency f₀. The amplification factors are then correlated with each of the individual site parameters; four other “twin-parameter”—couples (f₀, V_SZ)—are also considered and the correlation with amplification factors is performed through a normalization of the frequencies by each site fundamental frequency. The quality of the correlations is given by a misfit compared with the original data variance. The largest variance reduction is obtained with twin-parameter characterizations, out of which the couple (f₀, V_S30) proves to provide the lower misfit. The performance of single parameter correlations is relatively lower; however, the best single parameter proves to be the fundamental frequency, which provides smaller misfit than the Vsz parameters. A comparison is also performed with the amplification factors recommended in European regulations, showing that it is possible right now to significantly improve both the site characterization criteria and the associated amplification factors, for use in building codes and microzonation studies.     

Metropolitan-scale Transport and Dispersion from the New York World Trade Center Following September 11, 2001. Part II: An Application of the CALPUFF Plume Model

Following the collapse of the New York World Trade Center (WTC) towers on September 11, 2001, Local, State, and Federal agencies initiated numerous air monitoring activities to better understand the ongoing impacts of emissions from the disaster. The collapse of the World Trade Center towers and associated fires that lasted for several weeks resulted at times in a noticeable plume of material that was dispersed around the Metropolitan New York City (NYC) area. In general, the plume was only noticeable for a short period of time following September 11, and only apparent close to the World Trade Center site. A study of the estimated pathway which the plume of WTC material would likely follow was completed to support the United States Environmental Protection Agency’s 2002 initial exposure assessments. In this study, the WTC emissions were simulated using the CALMET-CALPUFF model in order to examine the general spatial and temporal dispersion patterns over NYC. This paper presents the results of the CALPUFF plume model in terms of plume dilution and location, since the exact source strength remains unknown. Independent observations of PM_2.5 are used to support the general dispersion features calculated by the model. Results indicate that the simulated plume matched well with an abnormal increase (600–1000% of normal) in PM_2.5 two nights after the WTC collapse as the plume rotated north to southeast, towards parts of NYC. Very little if any evidence of the plume signature was noted during a similar flow scenario a week after September 11. This leads to the conclusion that other than areas within a few kilometers from the WTC site, the PM_2.5 plume was not observable over NYC’s background concentration after the first few days.     

Black carbon aerosols and their radiative properties in the Pearl River Delta region

The climatic and environmental effects of atmospheric aerosols are a hot topic in global science community, and radiative properties of the aerosols are one of the important parameters in assessing climatic change. Here we studied the black carbon concentration and absorption coefficient measured with aethalometers, scattering coefficient measured with nephelometers, and single scattering albedo derived at an atmospheric composition watch station in Guangzhou from 2004 to 2007. Our main results are as follows. The data of black carbon concentration and absorption coefficients measured with instruments cannot be directly used until they are measured in parallel with internationally accepted instruments for comparison, calibration, and reduction. After evaluation of the data, the result shows that the monthly mean of BC concentration varies 3.1–14.8 μg·m⁻³ and the concentration decreases by about 1 μg·m⁻³ in average over the four years; It is higher in the dry season with a multi-year mean of 8.9 μg/m³ and lower in the rainy season with a multi-year mean of 8.0 μg·m⁻³; The extreme maximum of monthly mean concentration occurred in December 2004 and extreme minimum in July 2007, and a 4-year mean is 8.4 μg·m⁻³. It is also shown that monthly mean scattering coefficient derived varies 129 −565 Mm⁻¹, monthly mean absorption coefficient 32–139 Mm⁻¹, and monthly mean single scattering albedo 0.71–0.91, with annual mean values of 0.80, 0.82, 0.79 and 0.84 for 2004, 2005, 2006 and 2007, respectively. Three instruments were used to take simultaneous measurements of BC in PM₁₀, PM_2.5, and PM₁ and the results showed that PM_2.5 took up about 90% of PM₁₀ and PM₁ accounted for about 68% of PM_2.5, and BC aerosols are mainly present in fine particulates. The variability of BC concentrations is quite consistent between the Nancun station (141 m above sea level) and the Panyu station (13 m above sea level), which are 8 km apart from each other. The concentration in higher altitude station (Panyu) is consistently lower than the lower altitude station (Nancun), and the difference of annual mean is about 4 μg·m⁻³. Supported by Natural Science Foundation of China (Grant Nos. U0733004, 40375002, 40418008, 40775011), National High Technology R & D Program of China (Grant Nos. 2006AA06A306 and 2006AA06A308) and National Basic Research Program of China (Grant No. 2005CB422207)     

Source apportionment and secondary organic aerosol estimation of PM2.5 in an urban atmosphere in China

PM2.5 is the key pollutant in atmospheric pollution in China.With new national air quality standards taking effect,PM2.5 has become a major issue for future pollution control.To effectively prevent and control PM2.5,its emission sources must be precisely and thoroughly understood.However,there are few publications reporting comprehensive and systematic results of PM2.5 source apportionment in the country.Based on PM2.5 sampling during 2009 in Shenzhen and follow-up investigation,positive matrix factorization(PMF)analysis has been carried out to understand the major sources and their temporal and spatial variations.The results show that in urban Shenzhen(University Town site),annual mean PM2.5 concentration was 42.2μg m?3,with secondary sulfate,vehicular emission,biomass burning and secondary nitrate as major sources;these contributed30.0%,26.9%,9.8%and 9.3%to total PM2.5,respectively.Other sources included high chloride,heavy oil combustion,sea salt,dust and the metallurgical industry,with contributions between 2%–4%.Spatiotemporal variations of various sources show that vehicular emission was mainly a local source,whereas secondary sulfate and biomass burning were mostly regional.Secondary nitrate had both local and regional sources.Identification of secondary organic aerosol(SOA)has always been difficult in aerosol source apportionment.In this study,the PMF model and organic carbon/elemental carbon(OC/EC)ratio method were combined to estimate SOA in PM2.5.The results show that in urban Shenzhen,annual SOA mass concentration was 7.5μg m?3,accounting for 57%of total organic matter,with precursors emitted from vehicles as the major source.This work can serve as a case study for further in-depth research on PM2.5 pollution and source apportionment in China.     

Relationship between coral growth rate and sea surface temperature in the northern part of South China Sea during the past 100 a

To research the relationship between coral growth rate and sea surface temperatnre (T_ss), 5 cores of livingPorites lutea were collected from the Xisha Islands and the southern Hainan Island waters and measured. The results of the study show that there is an obviously positive correlation between the coral growth rates and theTss records from the northern part of South China Sea. The annual growth rates of the five samples ofPorites lutea during the past 100 a are in the range of 7—15 mm/a, and their mean value is 11 mm/a. The correlation coefficients between the coral growth rates and the T_ss records from the waters during 1961—1993 are in the range of 0.77—0.89. As a result, a thermometer of the coral growth rate is established. A hindcasting T_ss, in the waters from 1993 to 1961 has been obtained with an error of about 0.12—0.17°C. Based upon the calculated result, the rising rate of T_ss in the northern part of South China Sea during the past 100 a is 0.20°C. which is higher than that of the air temperature in China (0.09°C/100 a), but lower than that of the global temperature and that of T_ss in the tropical western Pacific Ocean. Project supported by the National Nutural Science Foundation of China and the Multidesciplinary Oceanographic Expedition Team of Chinese Academy of Sciences to the Nansha Islands.     

Possible interaction between tectonic events and seismic noise at Las Cañadas Volcanic Caldera,Tenerife, Spain

Continuous seismic noise is recorded in the volcanic island of Tenerife (Canary Islands, Spain). The origin of this noise, strongly augmented by anthropogenic contamination, is still under debate. In this paper, we discuss the relationship between this noise and the occurrence of local tectonic events in the same area. In particular, transitions are sought in the time evolution of dynamic parameters computed on the seismic noise, and examples are shown where abrupt transitions may be associated with the occurrence of tectonic events. These transitions provide further evidence of the existence of a natural origin for at least part of the seismic noise, which is strongly contaminated—if not dominated—by anthropogenic sources.     

Source parameters of bohai earthquake, July 18, 1969 and yongshan earthquake, May 11, 1974 determined by synthetic seismograms of teleseismic P waves

The source parameters of the Bohai Sea earthquake, July 18, 1969 and Yongshan, Yunnan earthquake, May 11, 1974 were determined by full — wave theory synthetic seismograms of teleseismic P waves. P+pP+sP wereform were calculated with WKBJ approximation and real integral paths. One — dimensional unilateral, finite propagation source was also considered. By trail — and — error in comparing the theoretical seismograms with the observational ones of WWSSN stations, the source parameters were obtained as follow: for Bohai earthquake, φ=195°, δ=85°, λ=65°,M _o=0.9×10¹⁹Nm,L=59.9km.V _R=3.5km/s, ∧ _R =160°; for Yongshan earthquake, φ=240°, δ=80°, ∧=150°,M _o=1.3×10¹⁸Nm,L=48.8km,V _R=3km/s, ∧ _R =−10°, where φ is strike, δ dip angle, λ slip angle,M _o seismic moment,L rupture length,V _R rupture propagation speed. As III type fractures the faulting propagated along the fault planes, and ∧ _R is the angle from the strike to the propagation direction. Yongshan earthquake showed complexity in its focal process, having four sub—ruptures during the first 60 seconds. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 1–8, 1991.