Environmental Protection

Tsunami Affected U.S. Groundwater Levels

Water level fluctuations were recorded as far away as Illinois, Virginia, Missouri and Florida

Earthquakes affect Earth’s intricate plumbing system. Whether you live near the notoriously active San Andreas Fault in California, or far from active faults in Florida, an earthquake near or far can affect you and the water resources you depend on.

The most recent earthquake in Japan affected water levels in groundwater wells all over the country. Water level fluctuations were recorded as far away as Illinois, Virginia, Missouri and Florida.

The most common effect on groundwater from earthquakes is an instantaneous water-level increase or decrease. Recovery to the pre-earthquake water level can be so rapid that no change is detected.

These spikes can occur thousands of miles from earthquake epicenters. Most of the time, these spikes have no consequences for groundwater supply or quality. In rare cases, water wells have become dry or begun flowing. In other cases, discharge of springs and groundwater to streams has increased, and new springs have formed. Groundwater quality can also become degraded as a result of earthquakes.

Responses of water levels in wells to earthquakes are influenced by such factors as the magnitude and depth of the earthquake, distance from the epicenter, and the type of rock that surrounds the groundwater. The depth of the well, whether the aquifer is confined or unconfined, and well construction also influence the degree of water-level fluctuations in wells in response to seismic waves. Some aquifers may even act as resonators, which may amplify the response.

SOURCE: USGS


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