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Good quarry design depends upon a ground model that reliably defines the quality, volume and spatial distribution of resource and waste. Most ground models are based on boreholes, sometimes with additional 2D or 3D control provided by ‘traditional’ geophysical surveys such as microgravity, resistivity and active seismic. However, for logistical and economic reasons, these may not always be practical options for site investigations. A new article published by some authors from the British Geological Survey showcases ‘passive’ seismic survey as a rapid alternative means of imaging the subsurface. Full Report

An intriguing presentation given by dr. Jayson Meyers (Resource Potential, Perth, Australia) that illustrates how passive seismic and other geophysical methods identify a young meteorite crater in Archaean greenstone of the Coolgardie Goldfield (Western Australia).   Full Report

Fortescue Metals has recently studied the applicability of the HVSR method to the assessment of mining embankment integrity. Embankments are common features in mine sites, necessary for tailings storage, surface water management or general infrastructure such as dewatering ponds. Even though their construction methodology can largely vary, the degree of compaction is a fundamental property to be assessed during the construction and to be monitored over time. The geometry of embankments is usually very well known, thanks to high precision topographic surveys: this allows to use the HVSR method to estimate the average shear wave velocities of different embankment parts, as shown in this report. The shear wave velocities can in turn be linked to the levees’ degree of compaction and to discriminate stable embankments from altering ones over time   Full Report

Fortescue Metals has recently studied the applicability of the HVSR method to the assessment of mining embankment integrity. Embankments are common features in mine sites, necessary for tailings storage, surface water management or general infrastructure such as dewatering ponds. Even though their construction methodology can largely vary, the degree of compaction is a fundamental property to be assessed during the construction and to be monitored over time. The geometry of embankments is usually very well known, thanks to high precision topographic surveys: this allows to use the HVSR method to estimate the average shear wave velocities of different embankment parts, as shown in this report. The shear wave velocities can in turn be linked to the levees’ degree of compaction and to discriminate stable embankments from altering ones over time Full Report

Introduction What is Seismic Instrumentation and Monitoring of Dams? Why Dams need Seismic Instrumentation and Monitoring? What are the advantages of Seismic Instrumentation and Monitoring in Dams?  Methodology & Technology How does seismic instrumentation and monitoring work?  Our Solutions for Seismic Instrumentation and Monitoring of Dams GMS Series Recorders for distributed and hybrid systems CR-6 Series Modular Multichannel Recording System for central and hybrid systems A wide variety of high quality sensors to measure acceleration, velocity, displacement, strain, tilt and environmental phenomena. Software solutions with highly customisable options  Introduction What is Seismic Instrumentation and Monitoring of Dams?  Seismic Instrumentation and Monitoring of Dams is a particular branch in Structural Health and Response Monitoring, which is an innovative method of monitoring structural status and performance without otherwise affecting the structure itself and under earthquake excitations. It utilises also features from shutdown / notification systems. The basic concept is to deploy strong motion accelerometers and associated data acquisition / analysis systems in a dam to detect exceedance of allowed performance criteria as well as identify and verify structural behaviour.  Why Dams need Seismic Instrumentation and Monitoring? The strength and serviceability of a dam can be considerably – even terminally – reduced by natural or human-made events, earthquakes, extreme levels of operation, uncontrolled structural changes and various other influences. Utilising seismic instrumentation and monitoring systems, timely notifications about any potential problems can be generated and behaviour of the dam can be monitored. The emerging use of seismic instrumentation and monitoring especially in the last decades, is a result of the increasing need for the monitoring of hazards and associated risks as well as a better management of the safety issues concerning the dams. This is further enhanced by the ongoing development and sophistication of sensors, data acquisition systems, communication technologies and other advances in technology.  In the past we have seen significant structural failures in dams due to earthquakes, such as Shih Kang Dam in Taiwan during the Chi-Chi earthquake in 1999. Events such as these drastically show how vulnerable dams can be if exposed to earthquake ground motions, ground deformation or overload.  Despite the progress in the dynamic analysis of dams, it is still not possible to reliably predict the behaviour of dams during very strong ground shaking due to the difficulty in modelling the inelastic behaviour of dams, the insufficient information on the spatial variation of ground motion and other factors. It is reported that the May 12, 2008 Wenchuan earthquake has damaged 1803 dams and reservoirs, and 403 hydropower plants with an installed capacity of 3.3GW (ref. Wieland, M., “Features of seismic hazard in large dam projects and strong motion monitoring of large dams”, 2009).  The factors that eventually lead to failure as well as their severity and effect on the structure can be measured and monitored with GeoSIG Seismic Instrumentation and Monitoring systems.  What are the advantages of Seismic Instrumentation and Monitoring?  GeoSIG Seismic Instrumentation and Monitoring systems not only help reducing risks and costs, but also help avoiding disaster by its notifications which allows to initiate early damage detection and therefore helps saving lives as well as assets.  Utilising the acquired data by the system, fundamental features of a dam may be identified such as the damping within the large dam structure, amplification of the ground motion along the path from the foundation or abutments to the crest, wave propagation within the structure, differential motions between abutments, natural frequencies, mode shapes and so on.  In addition, the system allows to rapidly evaluate the structural response thus provides a highly useful measure for decision making whether to allow normal operation or to initiate a more comprehensive inspection before doing so.  The ideal Seismic Instrumentation and Monitoring system provides you with on-demand information about your structure's measured features, as well as warnings concerning any exceedance detected. Therefore also significantly reduces repair costs through early damage detection, making the monitored structure safer, increasing the cost efficiency of its maintenance.  Advantages of Seismic Instrumentation and Monitoring for Dams include:  increased understanding of in-situ structural behaviour and characteristics  assurance of structural resilience and serviceability  reliable information based engagement of safety devices  opportunity to facilitate the timely warning of the population living in the downstream valley  factual data to check and to improve the seismic design criteria of the dam  decreased down-time for inspection and repair  development of rational maintenance/management strategies  increased value of the assets when compared to non-monitored properties  an increased effectiveness in allocation of scarce resources.  Additionally Seismic Instrumentation and Monitoring enables and encourages the reliable use of new and innovative materials and designs in engineering.  Methodology & Technology How does Seismic Instrumentation and Monitoring work?  Each dam is unique, therefore the monitoring system that must be applied is also singular. However there are typical system topologies which are recommended and have been in use since several years with success, which is fully covered by the long GeoSIG experience through more than 200 dam systems in place. In close cooperation with the owner/contractor, GeoSIG delivers tailor-made Seismic Instrumentation and Monitoring systems for each project.  Typically an absolute minimum of 4 measuring points is foreseen, one in the base of the dam, one on the crest, one at an abutment and one at a freefield point at a distance that is approximately 3-4 times the height of the dam.  Following image shows a recommended seismic instrumentation topology of a dam, please refer to the References section for further information.   At each measuring point a high dynamic mechanical force balance accelerometer is deployed. These devices collect raw acceleration data and transfer it to a Data Acquisition System (DAS). From the DAS, the data is collected and sampled. It can then be transmitted to an offsite location or stored locally for automatic, intelligent processing. The reliable level of remote monitoring eliminates the need for site visits. The system allows for tools to remove mundane data, noise, thermal, or other unwanted effects before storage, and to make data interpretation easier, faster and more accurate. Diagnostics convert abstract data signals into useful information about the structural response and condition.  Trigger levels for issuing warning signals or notifications (when previously defined values are exceeded) will be set according to its particular properties and capabilities, with reference to design, resistance, durability and stability.  GeoSIG Seismic Instrumentation and Monitoring solutions allow for the application of the Design versus Measurement methodology in terms of exceedance checks and notifications. Detailed state of the art and customisable data analyses are then used to enable reliable alerts and notifications in terms of email, SMS or visual and audible alarms. They even can be provided as automated relays to turn on or off desired machinery or operations. The results are automatically documented in customisable reports and can be automatically printed or transmitted to various recipients to enable rational, knowledge-based engineering decisions.  In essence, the variety of measurement, data acquisition and interpretation as well as notification and reporting techniques utilised by GeoSIG Seismic Instrumentation and Monitoring systems create “intelligent dams” that are safer, long-lasting, more secure, and cheaper to operate, maintain and insure.  References COSMOS Instrumental Systems for Diagnostics of Seismic Response of Bridges and Dams 2001 Darbre G R Strong Motion Instrumentation of Dams 1995 Darbre G R Design Implementation of strong-motion Instrumentation Arrays in Dams 1992 Darbre G R State of practice in earthquake analysis of dams 2000 Darbre G R Dam Safety in Switzerland 2005 Fedock J USGS OFR 82-469 Strong Motion Instrumentation of Dams FEMA-65 Federal Guidelines for Dam and Safety 2005 ICOLD B112 Neotectonic and dams Recommendations and case histories 1998 ICOLD B46 Seismicity and dam design 1983 ICOLD B52 Earthquake analysis for dams 1986 ICOLD B60 Dam monitoring General considerations 1988 ICOLD B62 Inspection of dams after earthquakes Guidelines 1988 ICOLD B68 Monitoring of dams and their foundations State of the art 1989 ICOLD B72 Selecting seismic parameters for large dams Guidelines 1989 ICOLD B74 Tailings Dam Safety 1989 ICOLD B87 Improvement of existing dam monitoring Recommendations and case histories 1992 ICOLD B98 Tailings Dams and Seismicity Review and Recommendations 1995 ICOLD B99 Dam Failures Statistical Analysis 1995 ICOLD Position paper Water Power dam safety and earthquakes Aug 2010 The National Academy of Sciences National Research Council Safety of Existing Dams 1983 Wieland M Earthquake safety of concrete dams 1994 Wieland M Earthquake Safety of Existing Dams 2006 Wieland M Earthquake Safety of Existing Dams 2006 Presentation Wieland M Seismic Aspects of Dam Design 2002 Wieland M Strong Motion Instrumentation of Dams EN 2002 Wieland M Strong Motion Instrumentation of Dams Response 2002 Wieland M The many Features of the Seismic Hazard in Large Dam Projects 2009

Earthquake Early Warning   Earthquakes are perilous and inevitable natural events, causing severe damage and loss of life. There is no proven method to forecast the precise occurrence time of an earthquake nor its location or size. Yet, utilising state of the art scientific methodologies as done in GeoSIG Earthquake Early Warning (EEW) solution, it is now possible to quite accurately assess the location and size as soon as an earthquake emerges using its non- destructive primary waves. Thus, warnings about a potential strong shaking can be generated almost instantaneously , until destructive secondary seismic waves arrive. Based on fast and reliable communication channels, this provides the crucial seconds to take measures which may help reduce catastrophic impacts of seismic events. After an earthquake, GeoSIG Rapid Response (RR) solution provides analytic and thematic information on the aftermath of the earthquake in terms of shake maps consisting of observed ground motion parameters as well as estimated damage distribution.    Short time lapse video demonstrates the concept and operation of earthquake early warning systems available through GeoSIG. Leaflet https://www.geosig.com/files//GS_Seismic_Monitoring_And%20Shutdown_V02.pdf https://www.geosig.com/files//GS_EEWRR_Solution.pdf

Download Santiago, Chile Tailings Dam Case Study Background Anglo American plc is a multinational mining company that is one of the world’s largest producers of copper. Los Bronces is Anglo American’s open-cut copper and molybdenum mine — one of the largest copper reserves in the world, located approximately 65 km northeast of Santiago, Chile, at an altitude of around 4,000m above sea level in the Andes Mountains. After being crushed, the ore is fed by conveyor to a grinding plant at Confluencia. After being made into slurry, the product is transported by pipeline to Las Tórtolas — a flotation plant, where it is processed. Las Tórtolas is located 45km from Santiago at about 750m above sea level. This complex also includes a tailings dam, which is used to store by-products of mining operations. The dam was recently raised as part of the complex’s expansion, allowing more recycled water to be used in production. Management and storage of mine process waste is an important aspect to the design and operation of a mine. This is why Anglo American sought to install a seismic network for their tailings dam. Challenge Chile is in the Ring of Fire. As a consequence of the March 1965 earthquake, the Chilean authorities issued in 1970 a norm to regulate the design, construction, and operation of sand tailings dams (Decree No. 86). This norm required deployment of strong motion instrumentation on tailing dams. The object of this project was to monitor the behaviour of the main wall (Muro Principal) of the Las Tórtolas tailings dam as well as a second wall to the west (Muro Oeste). Solution Our Partner GeoMediciones of Chile, with more than 43 years experience in the industry, is a leader in civil works instrumentation and an integrator of solutions and technologies. They have achieved a strong position in seismic monitoring systems and associated solutions in Chile and the surrounding region. Installing a seismic network enables the two walls to be monitored with data transferred to the intranet of the company so that essential people (with the right permissions) can gain access to the data event at real time. For the main wall, a GMSplus and AC-73-DH were installed; they transfer the data to an instrumentation server located in the main wall booth (“Caseta Muro Principal”) by Wi-Fi. On “Muro Oeste”, AC-73 and AC-73-DH are connected by cable ethernet to the instrumentation server, which in turn is connected to the company’s intranet by fiber optic. From the data server located in the server room in the IT office, GeoDAS software downloads any new data from the instrumentation server, then shares the event files on a Share Point, which is only accessible from the company’s intranet (and by the client, via VPN). GeoDAS is a graphical Microsoft Windows-based application. It provides the most comprehensive, intuitive and versatile features available in the earthquake, seismic, structural, dynamic and static monitoring and measuring industry. Fundamentally the program is used for instrument configuration and for acquisition of data provided by any standard GeoSIG instrument. Another solution using GeoSIG instruments, effectively showing that quality and reliability can also be cost-effective.

  Download Xiangjiaba Dam, SW China Case Study Background The Yangtze River is the longest river in Asia and the third longest river in the world. It is a vital part of life in the area. In order to control flooding downstream and control the flow of the Yangtze River, which facilitates transportation, shipping and irrigation downstream, a large gravity dam was opened in 2012 on the Jinsha River – a tributary of the Yangtze River in Yunnan Province and Sichuan Province, southwest China. The Xiangjiaba Dam replaces fossil fuel-burning power plants to become China’s third-biggest hydroelectric power station. The output of the generating station is connected to a ±800 kV HVDC link, the Xiangjiaba–Shanghai HVDC system, which transmits much of the power to Shanghai in east China, where the economy is booming. Challenge The Xiangjiaba Dam is a critical structure that affects many people, and it is built in a seismically active region. The Xianshuihe fault is one of the most active faults in southwest China. So seismic monitoring and structural monitoring are essential aspects for the dam. Solution GeoSIG Partner Earth Products China Limited, or EPC, was chosen to equip this vital dam and hydropower station with a system that would provide full seismic and structural monitoring. EPC is a total solution provider in all aspects of civil engineering testing products and is a proven leader its field. In August 2014, EPC installed 18 units of GMSplus and 18 AC-73 triaxial force balance accelerometers. GMSplus is a self-contained instrument and is equipped with an uninterruptible power-supply, which provides more than 24 hours autonomy. The GMSplus uses an “Intelligent Adaptive Real Time Clock” (IARTC) with self-learning temperature compensation, improving the accuracy of the RTC or TXCO significantly. The IARTC is able to synchronize with GPS or NTP to UTC timing to provide high timing accuracy. Optionally the unit itself can act as an NTP server as well. The instrument’s software processes data in real time. If triggered by a seismic event, GMSplus calculates a number of event parameters and reports them to a data centre immediately – just the solution for the Xiangjiaba Dam project. Another Solution using GeoSIG instruments and a capable Partner demonstrating that quality and reliability can also be cost effective.  

  Download Baixo Sabor, Bragança, Portugal Case Study   Background Field works for the Baixo Sabor Complex in Bragança, Portugal, started in 2008, with production beginning in 2016. There are two dams and a hydroelectric power station located in the Sabor River. They can generate 189 MW of power, with annual average production of energy at 460 GWh (230 GWh net). The reservoir created by the upstream echelon stretches over 60 km, and the reservoir created by the downstream echelon is about 9.6 km in length. This reservoir more than doubles the storage capacity of Portuguese water in the Douro River. Challenge The project is the largest recent power generation project in Portugal. The complex is designed to provide 20% of the nation’s energy reserve and to provide support for other hydroelectric power plants. It is located in an area of special historical and environmental interest. One aspect of monitoring required for the complex is a Seismic Observation System. Solution Such an important project required a respected company with vast experience in the field. Vórtice Equipamentos Científicos, Lda. – a GeoSIG Partner for more than 20 years – designed a custom seismic observation system for the Baixo Sabor Complex in four parts. The Free Field Sub-System included six remote stations with triaxial accelerometer, a solar panel power solution (400W – 400 Ah batteries), 3G remote communications (fixed ip), and was GPS referenced. The Upstream Dam Sub-System included five + one (master) stations with triaxial accelerometer, a fibre optics network connection, and was GPS referenced (master). The Downstream Dam Sub-System comprised one + one (master) stations with triaxial accelerometer, a fibre optics network connection, and was GPS referenced (master). The Central Processing System included a desktop computer with UPS, GeoDAS DBS software and SEISAN software. The seismic observation system provides automatic detection and central registry of events. It features automatic delayed upload of seismic data to the central processing unit, and automatic determination of location of seismic events. It also allows for broadcast alert of seismic events. Another Solution using GeoSIG instruments and a capable Partner effectively showing that quality and reliability can also be cost-effective.  

  Download Caren and Ovejeria Dams, Chile Case Study Background The great copper mines in Chile have experienced a continuous growth in mineral production rates in the last 30 years. This, coupled with low ore yield, has led to a significant increase in tailings production. In addition, the deposits of this mineral are of great dimensions, easily topping the thousand million tons of mineral. All of this indicates that the management and storage of the mine process waste has become significantly important in the design and operation of an existing or a new mine. The Ovejeria Dam in Andina, Chile, took five years to build and has been fully operational since December 1999. Its estimated useful life is 50 years. It includes an 86 km concrete canal to transport tailings from an on-site concentrator plant to the dam, including 22 km of tunnels. Ovejeria receives more than 60’000 tpd of tailings material from Andina, (95% of everything extracted from the mine), which is scheduled to increase by almost to around 244’000 tpd after the mine’s next expansion stage. Caren Reservoir, located 90 km SW of the city of Santiago, has served since 1986 for the disposal of tailings generated by El Teniente, the largest underground production copper mine in the world. The dam was designed in 12 stages with a final height of about 141 m, and it is estimated that by the end of its life the reservoir can store a total of 2,200 million m3 of tailings. As it stands today, the construction of stage 5 ends with a height of approximately 84 m. Approximately 600 million m3 of tailings are already stored in the dam. The lifeterm of the Caren Dam is expected to be between 2054 and 2064, depending on the future rate of generation of tailings, currently at 130’000 tonnes per day. Challenge Chile is in the Ring of Fire. As a consequence of the March 1965 earthquake, the Chilean authorities issued in 1970 a norm to regulate the design, construction, and operation of sand tailings dams (Decree No. 86). This norm provided required deployment of strong motion instrumentation on tailing dams. Solution Our partner GeoMediciones / C. Fahrenkrog y Cia Ltda. has achieved a strong position in seismic monitoring systems and associated solutions in Chile and the surrounding region. A configuration of 3 units of GSR-18 strong motion recorders with AC-63 triaxial accelerometers were deployed at Ovejeria, synchronized with GPS for timing, as well as solar panels, charge regulator and large capacity batteries were installed. The measurement locations were at free field, at dam foundation and at dam crest. At Caren Tailing Dam, a configuration of 3 units of GSR-18 strong motion recorders with AC-63 triaxial accelerometers were deployed, synchronized with GPS for timing, as well as solar panels, charge regulator and large capacity batteries were installed. The measurement locations were at freefield, at dam foundation and at dam crest. Once the data has been processed it is assessed and compared as dam behaviour against seismic design criteria applicable to dam operations. The project facilitated the development and improvement of dam emergency and safety measuring equipment within the context of increased awareness and contributed to the regional seismic data management systems. Another Solution using GeoSIG instruments and a capable Partner effectively showing that quality and reliability can also be cost-effective.  

  Download Beli Iskar Dam, Bulgaria Case Study Background The Beli Iskar Dam is situated 60 km from Sofia in the Rila National Park, Bulgaria, at the foot of the Moussala Summit and at an elevation of approximately 1,800 m. It was constructed in 1935-1945 and put into service in 1948. The main function of the dam is to balance the natural run-off of the Beli Iskar River and to provide water to the communities in the Rila Mountain region and parts of Sofia. The dam is of concrete gravity type, with a maximum height of 51 m and a crest length of 533 m. The dam underwent repairs from 1997-1999. In 2002, one of the most important construction projects in Bulgaria was the rehabilitation of the Beli Iskar Dam. Challenge Bulgaria occupies the central part of the most seismic region of Europe — the Balkans, and it is exposed to the influence of neighbouring active seismic zones. It does experience earthquakes. The 2012 Penik earthquake was 5.6 M and caused at least €11,000,000 worth of damage. In 2014, the Aegean Sea earthquake of 6.9 M was widely felt across parts of Bulgaria. The mandate for GeoSIG was a dam monitoring system for Beli Iskar Dam, requiring instrumentation to record seismic motions and other ambient dynamic activity in order to continuously monitor dam structural safety within the context of a safe operating dam environment. Solution The structural monitoring and measurement system, which was implemented by Start Engineering JSC, Sofia, in the Beli Iskar Dam consists of 3 x AC-23 accelerometers, 3 x GSR-16 strong motion recorders, the GXR-ICC interconnection set for the interconnection cabling and modem system, an alarm interface (GXRALC alarm module), and GeoDAS software for central processing and reporting. Once the data has been processed it is assessed and compared as dam behaviour against seismic design criteria applicable to dam operations. The project facilitated the development and improvement of dam emergency and safety measuring equipment within the context of increased awareness and contributed to the regional seismic data management systems. Another Solution using GeoSIG instruments showing that quality and reliability can also be cost-effective.  

  Download Enguri Dam, Georgia Case Study   Background Enguri Dam (sometimes spelled Inguri Dam) is one of the highest arch dams in the world, and it is located in the Enguri River in Jvari, Georgia, at an altitude of 240 m above sea level. It is part of the Enguri hydroelectric power station (HES). The dam is 271.5 m tall and 750 m wide. Its crest at 510 m altitude has a developed length of 728 m, and is 10 m thick. It has 14.5 km of high pressure tunnel that is 9.5 m in diameter, and five Francis-type generator units in the underground power plant, 275 Mw each. Construction of the dam started in 1961; it became temporarily operational in 1978, and it was completed in 1987. Repairs and refurbishment at Enguri HES took place in 1999, and in 2011 work began to complete the rehabilitation and to ensure safe water evauation towards the Black Sea. The Enguri Dam was inscribed in the list of cultural heritage of Georgia in 2015. Challenge Georgia has made a considerable investment in the dam and power station, and it plays an important role in the country. Georgia is situated in Caucasus, which is one of the most seismically active regions in the Alpine-Himalayan collision belt. Historical analysis shows that it is a region of moderate seismicity and that strong earthquakes have occured here in the past, including a 7M earthquake in the region of Racha in 1991, which killed 270 people. The scope of the Enguri project was of a dam monitoring system requiring instrumentation to record seismic motions and other ambient dynamic activity in order to continuously monitor dam structural safety within the context of a safe operating dam environment.  Solution The solution was to install 10 AC-63 force balance accelerometers, 10 GSR-18 strong motion recorders, an interconnection cabling and modem system (GXRICC interconnection set), and a central processing system center with processing and reporting software. Once the data has been processed it is assessed and compared as dam behaviour against seismic design criteria applicable to dam operations. The project facilitated the development and improvement of dam emergency and safety measuring equipment within the context of increased awareness and contributed to the regional seismic data management systems. Another Solution using GeoSIG instruments showing that quality and reliability can also be cost-effective.