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Portable seismograph for home

This small and easy to use device works as a low-frequency seismograph will allow any person to measure the vibrations of the Earth in their home, especially if they live in areas of high seismicity or intermediate soft ground and greater wave amplification such as the Colombian city of Manizales.

The inverted electromagnetic pendulum measures vibrations between 0.1 and 30 hertz (Hz), earth tremors oscillate between 1 and 100 Hz. This device is the smaller than any conventional seismograph, costs less than Col $300.000 pesos (US $105.00) while a traditional seismograph can cost approximately COL $20 million (US $ 7,040).

Universidad Nacional de Colombia (UNal) in Medellín Physical Engineering student Joaquín Orozco claims that despite its size and cost, the instrument provides specific data, as trustworthy as the devices in government agencies such as the Volcanology and Seismology Observatory of Manizales.

The prototype is compact, with parts made of acrylic plastic and aluminum, and no bigger than 30cm. (1.8in.) tall; and may be connected to a computer using USB and also uses a 5,000 DPI mouse laser, a quality feature as other types of devices only use a 50 DPI mouse.

“The upper part of the device has two magnets, each one 10cm. (3.9in.) in diameter, one is located on a platform with a sensor. In order to estimate frequencies between 2 and 30 Hz, the length of the stem may be shortened or extended between 10 and  25 cm. (9.8in.) and the distance between magnets is between 1 and 4cm. (0.3 - 1.5in.)”, said UNal Physical Engineering student Susana Veloza.

Data is acquired and inputted into a proprietary software program, which may be connected to a computer, tablet or cellphone.  The easy to use software program shows a chart of the vibrations in a determined space of time.

“Data into the software program may be altered, such as changing the frequency and also the time to begin measurements,” added the creators, who also said, “The instrument works by the physical principle of resonance, i.e. a pendulum oscillates when excited to a frequency of the same order in which it was configured although the amplitude of the vibration measurement is low.

Educational tool

One of the reasons the electromagnetic pendulum is useful for the community and specifically for people living in the coffee growing region of Colombia is that it encourages learning about seismography and how they are related to internal volcanic domes or rock fracturing due to high pressures, and gas production or magma.

Christian Camilo Patiño, operator of the Accelerometer Network of Manizales and the Seismic Information System says that they need to take into account that the areas of greater seismic activity are within what is known as the Pacific Ring of Fire, which has an extension of approximately 40,000 km (24,859 miles) ranging from New Zealand to the east coast of South America.

“The device designed by UNal-Medellín students is a great educational tool to show the general public how earth movements are measured, which can only and exclusively be performed in real time, ” said Geologists Camilo Andrés Porras Cobo.

According to these experts, the instrument is a great strategy to encourage citizens to use tools such as whistles and keep a stash of imperishable food and water in order to be prepared for any emergency.

Besides earth tremors

The device apart from measuring low-frequency vibrations may also be used to measure movements of buildings and pedestrian-only bridges which can vibrate at a range between 2 and 4 Hz.

Giordany González Civil Engineer of the firm Ingeniería Sísmica y Estructural  (Armenia, Province of Quindío), says that low-frequency seismograph field is very pertinent and that these types of devices should be compulsory in buildings, as these do not behave as they were designed but how they were built. Engineers can calculate, but real signals can tell us much about their vibration periods.

Furthermore, Veloza says that this proprietary seismograph could also be useful as an educational tool in schools and colleges to teach students about the physical principle of resonance and how it may be used for practical purposes.

The three creators now want to design a specific sensor for the seismograph with the purpose of diminishing costs and also to include additional information to make the device more commercially attractive.



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