That is, while it is certainly possible for water tables to rise or fall, for the composition of the atmosphere at the Earth's surface to change, or for the electron density of the ionosphere to drop before an earthquake, these phenomena can also be triggered by a number of other manmade and natural events, including rainfall, water pressure, over-extraction of groundwater, and geomagnetic storms.
舉例來說，大地震來臨前確實有可能發生地下水位、地表氣體的變動，以及大氣電離層濃度減少等現象，但除了地震以外，尚有降雨、水壓、超抽地下水、太陽磁暴等種種自然或人為因素，也可能造成這些異常現象。