The invention provides a novel method for monitoring strain on an
earth crust shallow layer. Practice proves that the strain on the
earth crust shallow layer is related to an earthquake precursor, so that the method is a novel method for monitoring the earthquake precursor. By the method provided by the invention, the characteristics of particle media are used, a
stress sensor is not arranged in a
drill hole of a
bed rock on an
earth crust deep layer but is embedded in sand of the earth crust shallow layer, and water around the
stress sensor is displaced into
clean water for washing sand in
spite of an
earth surface soil stratum or an
earth surface bed stratum. The
stress sensor is buried below a frozen soil layer and above an underground
water level.