Seismic Observations and Seismic Hazard Studies in the Philippines

It has taken more than a hundred years for seismic observations in the Philippines to evolve to a modern observation system. The responsibility of seismic observations was likewise transferred from one agency to another during this same period of time. At present, the mandate of conducting seismic observations in the Philippines rests with the Philippine Institute of Volcanology and Seismology (PHIVOLCS). In 2000, through a grant aid from the Japan International Cooperation Agency (JICA), the Philippine seismic network was upgraded to a digital system. As a result, a new set of seismic monitoring equipments was installed in all of the 34 PHIVOLCS seismic stations all over the country. Digital waveforms are now available for high level seismic data processing, and data acquisition and processing are now automated. Included in the upgrade is the provision of strong motion accelerographs in all stations whose data can now be used for studying ground motion and intensity attenuation relations. The new setup is now producing high-resolution data that can now be used for conducting basic seismological researches. Earthquake locations have now improved allowing for the modeling and delineation of earthquake source regions necessary for earthquake hazard studies. Current seismic hazard studies in the Philippines involve the estimation of ground motion using both probabilistic and deterministic approaches, seismic microzonation studies of key cities using microtremor observations, paleoseismology and active faults mapping, and identification of liquefaction-prone, landslide-prone and tsunami-affected areas. The earthquake database is now being reviewed and completed with the addition of historical events and from data from regional databases. While studies of seismic hazards were primarily concentrated on a regional level, PHIVOLCS is now focusing on doing these seismic hazard studies on a microlevel. For Metro Manila, first generation hazard maps showing ground rupture, ground shaking and liquefaction hazards have recently been completed. Other large cities that are also at risk from large earthquakes are the next targets. The elements at risk such as population, lifelines, and vertical and horizontal structures for each of these urban centers are also being incorporated in the hazard maps for immediate use of planners, civil defense officials, policy-makers and engineers. The maps can also now be used to describe possible scenarios during times of strong events and how appropriate socio-economic and engineering responses could be designed. In addition, a rapid earthquake damage assessment system has been started which will attempt to produce immediate or rapid assessments including identification of elements at risk during times of strong earthquakes.

Studies on the Hazardous Effects and the Maximum Allowable Concentration of Pyrophyllite Dust

Pyrophyllite (H2Al2,Si4 O22, ) dust (P-dust) is a mixture of silica (10-40% ), differentproportions of a luminium oxide (Al2O3 ), and various metal compounds. People with occupa-tions known to be associated with exposure to P-dust include miners, other industrial workersand persons engaged in artistic carving. Currently, little is known about pyrophyllite pneumo-coniosis from P-dust. This study was designed to investigate the hazardous effects of P-dustand to suggest a maximum allowable concentration (MAC) of the dust.This.study included four parts: (i) Occupational epidemiology surveys in 781 workersfrom 1 pyrophyllite mine (PM) and four pyrophyllite carving mills (PCM), with a registra-tion rate of 98 %. (ii) In vitro studies: Six groups of rats were expeed to different levels ofP-dust; the cytotoxicity of P-dust on rat alveolar macrophages (AM) was investigated by de-termining the potassium'content of AM and the activity levels of lactate dehydrogenase (LDH)in AM culture fluid. (iii) Mineralogical analysis of P-dust: The contents of silica (SiO2 ), alu-minium (Al), ferrum (Fe), niikel (Ni), zinc (Zn) and copper (Cu) in hath PM-dust andPCMdust were determined. (iv ) Determination of P-dust MAC: Using the life-talbemethod, an investigation of the hygiene standard of P-dust was carried out in 625 workers ex-POSed to either PM-dust or PCM-dust, uPon whom routine radiographs were Performed.The results suggest that the risk of developing pneumoconiosis from pyrophyllite dust issignificantly higher for PM workers than for PCM workers. The prevalence rate of PCM-dustpneumoconiosis is significantly higher in men than in women. The content of SiO2 and AlO3in the mixture of P-dust is the most important factor in the etiology of pyrophyllitosis. De-pending on the different P-dust MAC values, we suggest that 2 rng/m3 and 4 mg/m' shouldbe considered as the MAC for PM-dust and PCM-dust, respectively, and 3 mg/m' fOr P-dust. We believe that establishing different hygiene standards is more accurate even thoughworkers are exposured to the 'same' dust

Seismic Risk Perception Assessment of Earthquake Survivors: A Case Study from the 2005 Kashmir Earthquake

Following the catastrophic earthquake of October 2005 in Kashmir, Pakistan, 215 surveys were administered to earthquake survivors in villages within 50 miles (80 km) of the epicenter near the town of Muzaffarabad. The survey questionnaires were designed to address perceptions of seismic knowledge, event-related behavior, and opinions of local, regional, and national seismic preparedness and mitigation-representing a rare opportunity in seismic risk assessment. Some of the findings were similar to previous research results, while some were counter-intuitive, surprising, and valuable. Overwhelmingly, respondents stated that they ran away after the quake (vs. praying, taking cover, screaming, or doing nothing). Their trust in local and national governments regarding future earthquake preparedness and mitigation was high (~50%), contrary to most prior studies. Less than five percent of respondents believed that “no quake would occur again”, while nearly 75% responded that another quake would occur within 5 - 10 years, another opinion contrary to previous research. This research revealed new aspects of risk perception in the predominant Muslim communities of Northern Pakistan regarding recurrence, post-event action, and regional preparedness.

Studies of Earthquake Hazard Using Microseismicity Data in Modern Times

This paper selects some representative regions to obtain their G-R relation curves according to their seismicity characteristics,by using ML≥2.0 microseismicity data(1970~1993)in North China.The annual occurrence rate of events of each magnitude can be inferred from the G-R relation.At the same tune,the actual annual occurrence rate of earthquakes of higher magnitudes can be calculated from historical earthquakes(1300-1993)recorded in the same region.It seems that both results are almost the same.Therefore,the rate of events of higher magnitudes can be obtained by using microseismicity data when the proper region is selected.However,two points should be noticed:(1)The method can only give the annual occurrence rate in a seismicity system and estimate the whole situation of the system.(2)When there is a very large earthquake in and near the period in which the microseismicity data are applied,the actual occurrence rate of the system,including this larger earthquake,cannot be obtained by this method.

Application of a microseismic monitoring system in deep mining

A microseismic monitoring system was used in the Donggua Shan underground copper mine, and its application was introduced. The spacial distribution of the seismic event was monitored effectively during mining with this system. The distribution of the seismic intensity in different time periods and in the different mining districts was obtained via the clustering analysis of the monitored results, and the different intensity concentration districts of seismicity were compartmentalized. The various characteristics and waveforms of different vibrations in the underground mine were revealed with the help of the micro-seismic monitoring system. It was proved that the construction and application of the micro-seismic monitoring system in the mine not only realized the continuous monitoring of seismicity in the deep mine, but also settled an this system.

Consequence Identification for Maloperation in Batch Process

Batch processes are important in chemical industry,in which operators usually play a major role and hazards may arise by their inadvertent acts.In this paper,based on hazard and operability study and concept of qualitative simulation,an automatic method for adverse consequence identification for potential maloperation is proposed.The qualitative model for production process is expressed by a novel directed graph.Possible operation deviations from normal operating procedure are identified systematically by using a group of guidewords.The proposed algorithm is used for qualitative simulation of batch processes to identify the effects of maloperations.The method is illustrated with a simple batch process and a batch reaction process.The results show that batch processes can be simulated qualitatively and hazards can be identified for operating procedures including maloperations.After analysis for possible plant maloperations,some measures can be taken to avoid maloperations or reduce losses resulted from maloperations.

Calibration of local magnitude scale for Hindukush continental subduction zone

Hindukush is an active subduction zone where at least one earthquake occurs on daily basis.For seismic hazard studies,it is important to develop a local magnitude scale using the data of local seismic network.We have computed local magnitude scale for Hindukush earthquakes using data from local network belonging to Center for Earthquake Studies(CES)for a period of three years,i.e.2015–2017.A total of 26,365 seismic records pertaining to 2,683 earthquakes with magnitude 2.0 and greater,was used with hypocentral distance less than 600 km.Magnitude scale developed by using this data comes to be M_(L)=logA+0.929logr+0.00298r-1.84.The magnitude determined through formulated relation was compared with that of standard relation for Southern California and relation developed by the same authors for local network for Northern Punjab.It was observed that Hindukush region has high attenuation as compared to that of Southern California and Northern Punjab which implies that Hindukush is tectonically more disturbed as compared to the said regions,hence,seismically more active as well.We have calculated station correction factors for our network.Station correction factors do not show any pattern which probably owes to the geological and tectonic complexity of this structure.Standard deviation and variance of magnitude residuals for CES network determined using Hutton and Boore scale and scale developed in this study were compared,it showed that a variance reduction of 44.1%was achieved.Average of magnitude residuals for different distance ranges was almost zero which showed that our magnitude scale was stable for all distances up to 600 km.Newly developed magnitude scale will help in homogenization of earthquake catalog.It has been observed that b-value of CES catalog decreases when magnitude is calculated by using newly developed magnitude scale.

SDG-Based HAZOP and Fault Diagnosis Analysis to the Inversion of Synthetic Ammonia

This paper presents some practical applications of signed directed graphs （SDGs） to computeraided hazard and operability study （HAZOP） and fault diagnosis, based on an analysis of the SDG theory. The SDG is modeled for the inversion of synthetic ammonia, which is highly dangerous in process industry, and HAZOP and fault diagnosis based on the SDG model are presented. A new reasoning method, whereby inverse inference is combined with forward inference, is presented to implement SDG fault diagnosis based on a breadth-first algorithm with consistency rules. Compared with conventional inference engines, this new method can better avoid qualitative spuriousness and combination explosion, and can deal with unobservable nodes in SDGs more effectively. Experimental results show the validity and advantages of the new SDG method.