URGENT COMPUTING AND PHYSICS-BASED SIMULATIONS APPLIED TO THE EARTHQUAKE OF 19/09/1985
The morning of September 19, 1985, remains etched in the collective memory of the Mexican population. At 7:18 a.m., a magnitude 8.1 earthquake struck near Puerto Lázaro Cárdenas, Michoacán. The most significant damage and losses occurred not only in towns near the epicentral region but, unexpectedly, also in Mexico City—located approximately 400 km away. There, intense ground accelerations led to the collapse of numerous homes and buildings. Since that tragic event, Mexican seismology has undergone rapid development.
Technological progress and the use of high-performance computing (HPC) have enabled faster and more efficient solutions to complex problems in geophysics and engineering. Within this context, the concept of Urgent Computing emerges, referring to processes with unpredictable behavior that require substantial computational power and must deliver results within a strict time frame. When applied to geophysical phenomena, urgent computing involves execution priority in HPC environments, the use of advanced simulation algorithms, and open-access data to provide immediate estimates of the potential impacts and damage after extreme events.
In seismology, earthquake simulation requires preliminary information such as the hypocenter location, magnitude, and certain parameters of the seismic source. Although monitoring agencies typically report the location and magnitude within minutes, the detailed estimation of source parameters takes longer due to the complexity of inversion processes. In this framework, UCIS4EQ (Urgent Computing Integrated Services for Earthquakes) has been developed—a fully automated workflow that performs physics-based seismic simulations in parallel on HPC systems, considering characteristic focal mechanisms for the region where a large earthquake has occurred. This tool enables statistical analysis of ground motion intensity measures and generates maps of their spatial distribution. Its goal is to support relevant agencies in decision-making processes following a potentially destructive earthquake.
In this study, we present the application of UCIS4EQ to the simulation of the September 19, 1985 earthquake. The main objective is to demonstrate its scientific validity and technological maturity for use as an operational tool in response to future damaging earthquakes in Mexico with similar characteristics. Additionally, we discuss the advantages and limitations of using HPC and physics-based simulations for seismic hazard assessment. Moreover, these simulations allow for the generation of synthetic seismograms at both uniformly distributed grid points and real seismic stations, facilitating the comparison and validation of the obtained results. Consequently, the intensity measures derived from UCIS4EQ —produced through physics-based earthquake simulations— can complement ground motion estimates based on empirical Ground Motion Models (GMMs), that have long been a traditional tool for seismic hazard assessment.