Did you know? Earthquakes can affect groundwater levels?
We often see a response to large (and sometimes not so large) earthquakes in groundwater levels in wells. The USGS maintains a network of wells for monitoring various things like natural variability in water levels and response to pumping and climate change across the U.S.
The M8.1 earthquake that took place September 8, 2017 in the Pacific region offshore Chiapas, Mexico was observed across the U.S. in confined aquifer wells within the network. The wells in this plot are available from the National Water Information System (NWIS) web are from: TX, CA (southern), OK, MO, VA, CA (central), MD, NJ, PA, OH, NY and ME (from south to north). This is just a small sampling of the wells.
The frequency of data in these plots varies -- some are collected every minute, some every 15 minutes, and some hourly -- depending upon the purpose of the monitoring, giving different responses to the earthquake. The magnitude of the response depends on: local geology, hydrology, when the data point was collected, and when the seismic wave hit the aquifer that the well penetrates.