Earthquake Catalog Data

In the last decades, considerable effort has been expended in the collection and dissemination of global hazard information. Especially for earthquakes, there are various on-line databases publishing near real time hazard data. Such data can easily be used as input to natech risk assessment. In order to bene-fit from these sources, RAPID-N allows simple earthquake catalog data to be stored. It also has tools to follow on-line data sources to capture recent earthquake information and convert them into hazard re-cords with hazard parameters. Earthquake catalog data records form the basis of this functionality. The data fields of the earthquake catalog data records are listed in Table 1.

Table 1. Earthquake catalog data fields

The earthquake associated to the catalog data should be selected from the earthquakes available in the system. For each catalog data, the source catalog should be specified. Currently, three catalogs are sup-ported by the system: European Mediterranean Seismological Centre (EMSC), U.S. National Earthquake Information Center (NEIC), and U.S. Geological Survey (USGS). Since the date of the earthquake is avail-able in the hazard record, only the time is asked in the catalog data record. Epicenter, focal depth, and magnitude (with a scale) are requested as hazard parameters. The scale can be selected from the list of magnitude parameters available in the system. No mapping support is provided for the entry of the epi-center coordinates, since the catalog data comes from an external source and its value should be known explicitly. The source URL of the catalog data can be specified (Figure 1).

RAPID-N is pre-loaded with catalog data of earthquakes with a magnitude greater than 5.5 that occurred since 1973. The data source is NEIC database (U.S. NEIC, 2010). The system also has a web agent, which periodically follows earthquake catalog RSS feeds of the USGS (USGS, 2011b) and the EMSC (EMSC, 2011). If a new earthquake data is published at these sources, the system first checks whether the earthquake is available in the RAPID-N database. Epicenter, date and time of the earthquake are used to check the existence of the earthquake. Since these parameters are not exact and may differ slightly from catalog to catalog for a single earthquake, the system applies flexible thresholds for the comparison. Two earthquakes less than 30 seconds apart in time and 1.0 degree in distance are assumed to be the same. If the earthquake is found in the database, its hazard parameters are updated with the new cata-log data. More recent catalog data is assumed to be more precise than the older ones. If the earthquake is not found in the database and if it has a magnitude greater than 5.5 (on any scale), a new hazard re-cord is created for the earthquake with the hazard parameters in the catalog data (Figure 2). Catalog data is also stored separately as a catalog data record. Earthquakes with a magnitude of less than 5.5 are neglected to keep the earthquake database at a reasonable size. If needed, earthquakes with a lower magnitude can be added manually.

Owing to this automated follow-up feature, the earthquake database of RAPID-N is always kept up-dated. In the next version of the system, an automated risk assessment step will follow this step. The probability of natech events at the industrial plants found in the database will be assessed for the earthquake and results will be reported on the RAPID-N web site in near real-time.

REMARK: Catalog data is open to everyone, but can be created/modified only by the administrators.