Scientists are using their quake sensors to estimate damage, too

Laboratorio de Ingeniería Sísmica graphic This is a closeup of the interior of an accelerometer

The newest of three sensing networks in Costa Rica is not just for locating the epicenter of earthquakes. The system is designed for prediction, too.

That was the report from the Laboratorio de Ingeniería Sísmica of the Universidad de Costa Rica in a brief summary released Wednesday.

The Laboratorio was following up on its report of the quake Monday in the upper gulf of Nicoya. The Laboratorio had pointed out that damage would have been worse if the quake had happened closer to the surface. The estimated depth was 40 kilometers or about 25 miles.  There was little damage.

Both the Red Sismológica Nacional at the Universidad de Costa Rica and Observatorio Vulcanológico y Sismológico at Universidad Nacional in Heredia have sensing networks.

But the 70 devices distributed all over the country by the Laboratorio are much more than simple sensors. They measure the earth movement during an earthquake and chart it using the standard term in physics of centimeters per second squared. Basically the constant is the force of gravity so there is a common measurement unit.

The Laboratorio said that it plans to install 10 more units this year in high buildings.

The units are accelerometers made by the Plano, Texas, firm of  Refraction Technology, Inc. Said the company on its Web site:

Accelerometers are devices that measure the acceleration of motion of structures as well as subsurface monitoring of the ground . . . . Because no coils or magnets are used, the accelerometer is inherently stable over temperature, with excellent reliability, linearity, hysteresis, and noise levels.

Because the measurement is standardized, the Laboratorio can engage in speculation. For example, technicians and scientists created a simulation of a 6.0 earthquake in the mountains south of San José near Tobosi where a flurry of smaller quakes have taken place. The scientists can then estimate in standard units the impact on surrounding areas to estimate probably damage.

The simulation allows the Laboratorio to identify areas that would sustain the most damage, it said. The differences in the value of the motion during real quakes gives an indication of the soil composition. The Laboratorio said that San José Centro would be affected slightly less than Cartago, except for a portion of La Sabana, based on the data from the simulation.

The sensors are connected via the Internet to a central computer where the Laboratorio scientists can make estimates of the location of earthquakes but in a way that is different than the two other networks. The Laboratorio scientists have gained a reputation of pinpointing and estimating the magnitude of an earthquake quicker than their colleagues in other agencies.

The data was available just 10 minutes after the Monday quake.

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