Assessment of the IMERG Early-Run Precipitation Estimates over South American Country of Chile

Accurate rainfall measurement is a challenge, especially in regions with diverse climates and complex topography. Thus, knowledge of precipitation patterns requires observational networks with a very high spatial and temporal resolution, which is very difficult to construct in remote areas with complex geological features such as desert areas and mountains, particularly in countries with high topographical variability such as Chile. This study evaluated the performance of the near-real-time Integrated Multi-satellite Retrievals for GPM (IMERG) Early product throughout Chile, a country located in South America between 16°S–66°S latitude. The accuracy of the IMERG Early was assessed at different special and temporal scales from 2015 to 2020. Relative Bias (PBIAS), Mean Absolute Error (MAE), and Root-Mean-Squared Error (RMSE) were used to quantify the errors in the satellite estimates, while the Probability of Detection (POD), False Alarm Ratio (FAR), and Critical Success Index (CSI) were used to evaluate product detection accuracy. In addition, the consistency between the satellite estimates and the ground observations was assessed using the Correlation Coefficient (CC). The spatial results show that the IMERG Early had the best performance over the central zone, while the best temporal performance was detected for the yearly precipitation dataset. In addition, as latitude increases, so do errors. Also, the satellite product tends to slightly overestimate the precipitation throughout the country. The results of this study could contribute towards the improvement of the IMERG algorithms and open research opportunities in areas with high latitudes, such as Chile

Vulnerable areas determination based on seismic response at Chile center region

Chile is one of most seismic countries in the world. In the past 100 years, more than 8 major seismic events occurred in Chile, with the coastal area of central Chile being one of the most affected Since 2007, nearly 2,306 earthquakes were recorded in this area with magnitudes varying between 1.9 and 6.9 in the Ritcher and Mercalli scales. The earthquakes’ impact on the engineering structures depends on several factors, such as: the depth of the wave, wave type, geomorphological aspects of the rock, and soil properties. Chile central region of is a very important economics area, but at the same time, very vulnerable. The cities existing on this area, are installed in coastal plains, limited by Coastal Mountains and Pacific Ocean. Most of the seismic activity episodes recorded by Nacional Seismological center (CSN) is on the ocean. The present research aims to identify the regions vulnerable to significant seismic activities based on the average shear wave velocity on the upper 30m (Vs30) and using Geographic Information Systems. The Vs30 values were measured by the United Stated Geological Service (USGS). This analysis is based on the topography, geological units classified by Chilean norms NCh433, NCh2369, and law decree 61/ 2011. The analysis indicated that last epicenter city, Cobquecura, is the low vulnerable area, considering high Vs30 values and low number of habitants. Cities as Concepción, Talcachuano, San Pedro de la Paz, Coronel y Hualpén are more vulnerable because low Vs30 values, and high population. This factor can be associated to river mouths and floodplains presents in this area

Chilean Disaster Response and Alternative Measures for Improvement

Effective DRM aims to identify and minimize both hazards and vulnerabilities of a territory. This case study carried out in Chile analyzes national programs and disaster risk management structures at different administrative levels (national, regional, and municipal) and identifies gaps that contribute to the vulnerability of the current system. The proposed measures and options for improvement presented in this study are based on a literature review of scientific discussions about international governance, disaster risk management, and case studies conducted in Chile. The results indicate that the national disaster risk management plan has been adjusted in recent years, especially after the 2010 Chilean earthquake. The national administration, which is primarily responsible for managing potential risks, as well as the regional and local governments, has been replaced by the National Disaster Prevention and Response System (SINAPRED) in 2021, according to the 21364 law. This law was created to make cities more resilient, contributing to the Sustainable Development Goals (SDGs). This change is intended to decentralize disaster risk management, considering local conditions and preventing oversight of disaster risk management, which is not mandatory at the local level. It has also noted some gaps, such as the lack of standardization of emergency and early warning systems and funding at local levels. It is hoped that the system will move forward in this transition period and that the gaps will not affect effective risk management, as they have caused loss of life in past disasters

Signals of Surface Deformation Areas in Central Chile, Related to Seismic Activity—Using the Persistent Scatterer Method and GIS

Interferometric synthetic aperture radar is an effective means of measuring changes in the altitude of the Earth’s surface. In this research, the areas of surface deformation associated with low- and medium-intensity seismic events in Central Chile were analyzed using SENTINEL 1 satellite radar interferograms and geographical information system (GIS) tools. The persistent scatterer method was used to reduce noise from conventional InSAR methods. The results revealed that the coastal zone of Central Chile has a high density of daily earthquakes with a prevalence (93.03%) of low- and medium-intensity earthquakes. Monthly deformation maps were developed for the coast of the Biobio region in Central Chile. A clear deformation pattern is defined along the coast, being greater in the Arauco, Lota and Lebu areas. It was also shown that there was a slight upward trend in the north and northeast zone (i.e., δup ~3 mm/year), while there was an obvious accentuated upward trend (i.e., δup ~24 mm/year) in the southern part. This movement increases as latitude increases. This pattern is related to the daily seismic activity, the product of the movement between plates, and the geological faults located in the area. The deformation and trend maps provide certainty in terms of where hotspots are located, e.g., the most hazardous areas in the study zone, which can be applied to urban planning and/or safety assessment

Signals of Surface Deformation Areas in Central Chile, Related to Seismic Activity—Using the Persistent Scatterer Method and GIS

Interferometric synthetic aperture radar is an effective means of measuring changes in the altitude of the Earth’s surface. In this research, the areas of surface deformation associated with low- and medium-intensity seismic events in Central Chile were analyzed using SENTINEL 1 satellite radar interferograms and geographical information system (GIS) tools. The persistent scatterer method was used to reduce noise from conventional InSAR methods. The results revealed that the coastal zone of Central Chile has a high density of daily earthquakes with a prevalence (93.03%) of low- and medium-intensity earthquakes. Monthly deformation maps were developed for the coast of the Biobio region in Central Chile. A clear deformation pattern is defined along the coast, being greater in the Arauco, Lota and Lebu areas. It was also shown that there was a slight upward trend in the north and northeast zone (i.e., δup ~3 mm/year), while there was an obvious accentuated upward trend (i.e., δup ~24 mm/year) in the southern part. This movement increases as latitude increases. This pattern is related to the daily seismic activity, the product of the movement between plates, and the geological faults located in the area. The deformation and trend maps provide certainty in terms of where hotspots are located, e.g., the most hazardous areas in the study zone, which can be applied to urban planning and/or safety assessment