Search

The Non-homogeneous Poisson Process, with time-dependent intensity functions, is commonly used to model the scenario of counting the number of events that appear to occur in a given time interval. The identification of the process relies on the functional form of the intensity function, which can be difficult to determine. In this paper, a Non-Homogenous Poisson Process model is proposed to predict the intensity function for the number of earthquake occurrences in Iraq; the constructed model allows anticipating the number of earthquakes that occur at any time interval with a specific time length. Then, to estimate the model parameters, the data obtained from the annual reports of the Iraqi Meteorological Organization and Seismology (IMOS) from January 1st 2018 to April 30th 2023 are used. Moreover, a simulation study is conducted and a new algorithm is introduced to show the performance and applicability of the proposed model. [ABSTRACT FROM AUTHOR]

Foreshocks are spatially clustered seismic events preceding large earthquakes. Since the dawn of seismology, their occurrence has been identified as a possible mechanism leading to further crustal destabilization, hence, to major failures. However, several cases occurred without any previous anomalous seismic activity, so that the hypothesis of foreshocks as reliable seismic precursors fails to pass statistical tests. Here, we perform an all‐round statistical comparative analysis of seismicity in Southern California to assess whether any differences can be identified between swarms and foreshocks. Our results suggest that extremely variable seismic patterns can forerun mainshocks, even though they tend to be preceded by clusters with more numerous events spread over larger areas than swarms and with a wider range of magnitudes. We provide a physical explanation of such dissimilarity and conclude, despite it, that foreshocks can hardly be reliable short‐term precursors of large earthquakes in California. Plain Language Summary: Large earthquakes can be preceded by a wide range of different seismic anomalies. Among these, seismicity has been reported to increase both in magnitude and frequency, but, on the other hand, it can also undergo a short period of reduced intensity before major events. The first pattern corresponds to the occurrence of foreshocks, that is, small to moderate quakes forewarning an upcoming larger one, while the second behavior is called seismic quiescence. In our research, we focus on foreshock activity. We perform an analysis of seismicity in Southern California, for which a well‐provided relocated earthquake catalog is available. While several studies have been conducted so far about what happens before large earthquakes after their occurrence and also there are some works about foreshocks discrimination, a systematic analysis comparing properties of clusters of "swarms", seismicity without a major event, and "foreshocks" before their mainshock is missing. Are foreshocks different from swarms before the occurrence of the main event? Are foreshocks fore‐shocks? Our results suggest that foreshocks can hardly be distinguished from swarms until the largest event takes place. On the base of this analysis and theoretical modeling, we think that foreshocks have limited reliability, if considered alone, for short‐term forecasts. Key Points: The occurrence of mainshocks can be preceded by a wide range of seismic patternsForeshocks slightly differ from swarms in Southern California, but they can be hardly distinguished before mainshocksForeshocks are not reliable precursors of large seismic events [ABSTRACT FROM AUTHOR]