This paper aims to develop a new statistical measure to identify significant correlations among multiple events with spatial and temporal components. This new measure, ( , )K r t , is defined by adding the temporal dimension to Ripley's ( )K r function. Empirical studies show that the use of ( , )K r t can lead to a more discriminating and flexible spatial-temporal data analysis framework. This measure also helps identify the causal events whose occurrences induce those of other events.