From the relationship between groundwater level change,
earthquake magnitude, and epicentral distance, the maximum
extent of stress influence can be calculated using the given earthquake
magnitude and the detected groundwater level change. This
relationship can be applied to estimate the area of anomalous
stress by using the cross areas from the observation wells obtained
with the intersection method. As stated above, the method assumes that the groundwater variation is caused by the transferred
stress from a suspected point, i.e., the stress source. The area
of anomalous stress can be delineated as the area between the
intersection points of circles plotted using influence radii from
multiple groundwater wells that respond to the earthquake