Updated
May 2, 2005 13:48

Getting a Grip on the Shakes

It’s the daily hustle and bustle—not just above ground, but miles below the earth’s surface. The earth’s plates and the viscous (semi-liquid) mantle below are constantly, actively churning. Most times, this activity causes little to no disturbance. But, as this churning continues and moves plates toward each other, the pressure builds as they jockey for position until one slight change triggers a sudden, very monumental shift. And that’s when the Richter scale and people nearby know there’s been an earthquake.

In 1557, in central China, the deadliest earthquake in modern time killed 830,000 people because they lived in caves made of soft rock. In 1960, the largest earthquake in modern time – 9.5. on the Richter scale – shook Chile and produced surface waves so powerful that 60 hours later they were still being recorded on seismographs. In 2004, an earthquake in the Indian Ocean spawned one of the deadliest tsunamis in history.

Each year, approximately 500,000 detectable earthquakes occur around the world – only 10,000 of those are probably felt, and less than 100 will probably cause damage. However, it’s the largest damaging earthquakes (probably no more than 10 a year) that cause the greatest concern. These cannot be predicted, and the damage can be disastrous. At Rosenstiel School, geologists and other scientists are working together to understand the conditions that lead up to earthquakes and help earthquake-prone areas best prepare for these natural disasters.

Learning the earth’s moves
A key part to earthquake study has to do with geodesy, or learning how the earth is moving. Rosenstiel scientists rely on ultra-high precision GPS to track movements all around the globe. Approximately 1,000 instruments set up around the world provide gigabytes of data that paint a picture of earth movement – ocean and earth tides, atmospheric pressure, and satellites in varying orbits. Literally dozens of natural processes will demonstrate changes indicating movement. Some of these processes are well known and expected; some only somewhat understood, and some not known at all.

Getting the star’s-eye view
Satellite imagery from Rosenstiel School’s Center for Southeastern Tropical Advanced Remote Sensing (CSTARS) provides real-time, high-resolution imagery that is especially useful in studying earthquakes. Rosenstiel scientists can measure displacements precisely and also use this information to corroborate or calibrate models that they are developing to better anticipate and understand these changes.

It’s in the numbers
From the gigabytes upon gigabytes of data received, Rosenstiel School researchers develop mathematical models using high-performance computing. This kind of modeling can help estimate the size of future earthquakes and the most likely locations from which they’d originate. Equally important, scientists learn how the pushing and pulling or “strain” accumulates and releases with the earthquakes.

How to prepare for the unpredictable
It’s highly unlikely that scientists will ever be able to conclusively forecast an earthquake’s location, arrival time, and size. That’s why, in Rosenstiel School’s Marine Affairs and Policy Division, researchers are providing a unique and distinctive perspective on natural disasters. These researchers consider how a society can address its vulnerabilities through better urban planning and practical public education. Researchers here weigh how predictive information reduces risks versus long-term mitigation, such as changing building codes to require steel structures in these earthquake-prone areas.

By learning more about earthquakes, Rosenstiel School scientists believe this new knowledge will be “power” as it helps communities be as prepared as they can be for one of nature’s most challenging phenomenons.

For more information, contact:
Barbra Gonzalez, Communications Director
Rosenstiel School of Marine and Atmospheric Science
305.421.4704 • barbgo@rsmas.miami.edu

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