Strong Motion Networks
Strong Motion Seismology may be referred to as science and technology based on strong motion network data and earthquake disaster records near earthquake sources. The objective of creating strong motion networks is to generate data to study source dynamics of generated ground motions from seismic sources. A further objective is the analysis of seismic-wave propagation effects due to complex geological structures in propagation-path from source to site, including wave attenuation and scattering. Finally, the amplification and de-amplification of seismic motions due to surface geological and topography, including nonlinear behaviour of soils for strong motions. Then as a goal, it is to develop methodologies (a.k.a. GMPEs) of predicting strong ground motions from seismic sources related to active faults and subduction-zones with high probability of earthquake occurrence in order to mitigate earthquake disaster.
The data generated from Strong Motion Networks are used for earthquake emergency response, for improving engineering designs, and for research in seismology. For earthquake emergency response, applications such as the ShakeMaps use strong-motion data as input and generate near-real time information on the levels of ground shaking and loss assessment for emergency responders. Structural and earthquake engineers use strong motion recordings to verify or improve design codes.
Case Study:Strong Motion - NetQuakes, USA
Any country as large as the USA faces difficult choices within its earthquake monitoring strategy. Striking the right balance between the possibility of a large earthquake in a remote area causing little disruption and a smaller earthquake in a densely populated causing massive damage is a risk to be very carefully managed. A current area of significant risk has been identified as surrounding the San Francisco East Bay and the Hayward fault areas.
On 6 Jun 2009 a 3.1 earthquake rattled the East Bay, but there were no immediate reports of injury or damage. Scientists then probed the Lucas Valley for earthquake clues as the one almost certain thing around the East Bay area is that something bigger now appears to be looming. On 25 Jun 2009 the USGS described the Hayward fault as “a tectonic time bomb, due any time for another magnitude 6.8 to 7.0 earthquake and that the coming Hayward fault earthquake will probably kill hundreds of people and cause damage worth perhaps $100 billion.” This locality has therefore been identified as an area where the precise seismic risk of earthquake is not yet fully understood.
The USGS is trying to achieve a denser and more uniform seismograph spacing in the Bay Area to provide better measurements of ground motion during earthquakes. Our Partner — Seismic Systems in Simi Valley, California, USA — specializes in purchasing, installation, and service of earthquake and monitoring equipment, and they have been licensed by the City of Los Angeles for over 20 years. Seismic Systems was chosen to implement the solution. To do this, over 500 NetQuakes stations to date have been deployed to communicate their data to the USGS via the Internet. These instruments connect to an existing local network using WiFi and use existing Broadband connections to transmit data after an earthquake. This new instrumentation has been sought to monitor the emerging situation and included finding suitable locations within builtup areas to accept and install earthquake monitoring systems.
The NetQuakes seismographs specification requires access to the Internet via a wireless router connected to an existing Broadband Internet connection. The seismograph then transmits data to the USGS only after earthquakes above the magnitude of around 3, but will not consume any significant bandwidth and should require only minimal maintenance. The stations include NQS software designed for and in coordination with USGS to operate under a linux OS environment. Volunteers in private residences, businesses, public buildings and schools with an Internet connection in certain locations each host a seismograph.
While enhancing the Strong Motion Network coverage in this seismically high-risk area, the measurements improve also the ability to make rapid postearthquake assessments of expected damage and contribute to the continuing development of engineering standards for construction projects. They may well also shape future requirements within other urban areas over a longer time period.
Another Solution using GeoSIG instruments and a capable Partner effectively showing that quality and reliability can also be cost-effective.
Case Study:Strong Motion Network, India
ISR Strong Motion Network, India
The Indian subcontinent has a history of devastating earthquakes. The major reason for the high frequency and intensity of the earthquakes is that the Indian plate is driving into Asia at a rate of approximately 47 mm/year. Geographical statistics of India show that almost 54% of the land is vulnerable to earthquakes. On December 26, 2004, the third deadliest earthquake in the history of the world occurred off the west coast of northern Sumatra. The earthquake had a magnitude of 9.1. The tsunami that was generated killed 15,000 people in India. Because of the frequency and intensity of earthquakes there, India takes earthquakes very seriously. The Institute of Seismological Research (ISR) -- under the Science and Technology Department, Government of Gujarat -- formed in 2006. ISR is the only institute in India fully dedicated to seismological research; it is working to quickly develop into a premier international institute.
To become a premier international institute, ISR is developing a seismic network. Their goal was to establish 19 broadband seismic stations (BSS) throughout the state for seismic zonation of the State of Gujarat in western India.
To connect these seismic observatories, ISR needed a technologically advanced and reliable system. GeoSIG, through its Partner Gannon Dunkerley & Co., Ltd., was able to provide 300 x GSR-18 and 300 x AC-63 sensors. The BSS observatories are connected by VSAT to the Centration Station at Gandhinagar. The seismic activity is monitored round the clock. The details of any regional earthquake are reported within a few minutes. In addition, GeoSIG was able to provide training regarding the equipment. With its increasingly extensive network of observatories, ISR is able to measure seismic activity for use in: earthquake hazard assessment, earthquake prediction research, national and international scientific collaboration, published papers, and making long-term earthquake prognosis.
Case Study:Strong Motion Seismic Network - Turkey
According to the AFAD – the Disaster and Emergency Management Presidency of Turkey (or Afet ve Acil Durum Yönetimi Baskanligi in Turkish) – website, Turkey ranks third in the world in terms of earthquake-related casualties and eighth in the world with regard to the total number of people affected. Turkey experiences at least one 5+M earthquake annually, making proper disaster management and coordination crucial. AFAD has identified its vision as: “Being a leading and coordinating organization which offers a model that can be taken at the international level as being, based on sustainable development, risk-centred, efficient, effective and performing reliable service in the studies related to disaster and emergencies,” and its mission as “Building a disaster-resilient society.”
As one of its early goals, AFAD wanted to detect the epicentres of earthquakes in Turkey and the region with 99% accuracy and a 1-km margin of error by the end of 2017. Other goals included increasing risk reduction activities by 20% every year, improving preparedness and response capacity by 25% on average every year by the end of 2017, improving recovery capacity and processes by 20% every year, and developing disaster management support systems by the end of 2017.
Over the course of the past few years, our Partner, Sangari Uluslararasi Ticaret A.S., of Turkey, won tenders to supply more than 200 seismic stations to expand Turkey’s strong motion network.
The seismic stations comprise GMSplus high dynamic-range strong motion accelerographs with internal AC-73 accelerometers, which offer real-time data streams over GPRS/3G network. The seismic stations also include a specific field station cabinet, high performance uninterrupted power supply, and other accessories.
GeoDAS software in the data center receives streams from all stations of the AFAD seismic network. It monitors state of health of stations and displays their status on the map. Every detected and recorded seismic event is preprocessed and converted to the specific data format of AFAD Earthquake Department. Apart from that, one can request from all or from selected stations any fragment of data recorded within the last few eeks, and process it accordingly.
Another solution with a capable Partner using GeoSIG products proving quality and reliability can also be cost effective.