INGV and other networks station integration in time

Catalogo della Sismicità Italiana: fasi

The Italian Seismicity Catalog 2.0 is an update of the phases integrated dataset CSI 1.1 1981-2002

To Download the phases (text) files please use the drop-down menu "Download Phases" in the top-bar of this website.

To Download the stations (text) file please use the drop-down menu "Download Stations" in the top-bar of this website.

To cite this dataset (phases and/or stations):
Castello B., Di Stefano R. (2022) Catalogo della Sismicità Italiana (CSI): fasi (Version 2) [Data set]. Istituto Nazionale di Geofisica e Vulcanologia (INGV). https://doi.org/10.13127/csi.2.0/phs

Creative Commons Attribution 4.0 (CC BY 4.0)

Introduction

In order to associate arrival times recorded at several local permanent seismic networks monitoring the Italian peninsula complementary to the INGV National Seismic Network, we inherited and improved the integration method proposed by Chiarabba et al., 2005 for building the CSI catalog. The integration procedure strongly increases the overall number of locatable events and consequently the magnitude completeness of the catalog, mainly for the early years. Later on, the integration procedure essentially helps to improve the location quality by both increasing the number of observations (often close to the hypocenter) and decreasing the azimuthal gap.

Data

Merged P- and S-readings seismic bulletins from more than 400 seismic stations (permanent and regional) managed by INGV and other institutions, seismic observatories, University departments.

Method

P-arrival times from all the available bulletins for each year, have been merged with a semi-automatic binder-like approach (concatenated and ordered in P-picks time ascending order by automatic procedure for phase association and semi-automatic procedure to detect association errors)

Product

CSI2.0 1981-2008 P- and S-phases data-set, and stations coordinates organized in a list of site (aliases) co-located groups of stations codes.

Data

Italy and surrounding areas are currently monitored by more than 500 seismic stations belonging to the Italian seismic network (hereafter RSN, Rete Sismica Nazionale) managed by the INGV, whose signals converge to a centralized monitoring detection system. In the past decades, the station coverage of Italy was ensured by many different permanent networks such as the ING (currently INGV) and other institutions, seismic observatories, University departments. After 2005, the RSN strongly increased due to the installation of new three component seismic instruments with an important improvement of the recorded signal quality.
Data sharing occurred by direct collaborations with the Institutions managing the diverse networks or by downloading the respective bulletins via web. No one of the seismic bulletin (also including the INGV one) was taken as a reference for event detection. This choice was made to not bias the final dataset with a priori information. Only, in case of common station/observation between INGV and other networks, the INGV bulletin phase pick was considered authoritative.

Method

We further extend the CSI catalog of seismic phases up to 2008 by applying the phases’ integration method proposed by Chiarabba et al. (2005) and revising it by adding time-space post-processing controls on phase association based on both automatic and interactive inspection tools. In general, we observe that the new integration procedure strongly improves both catalog completeness and location quality because we increased the number of locatable events and the number of observations at stations close to the epicenters reducing the azimuthal gap.
P-arrival times from all the available bulletins for each year, have been concatenated and ordered in P-picks time ascending order.
Independently from the station provenance, the association of stations/picks in a single event (e.g., detection) is defined through a simple binding procedure based on the maximum time gap allowed between consecutive P arrivals to be part of the same event and unicity of a single station within an event.
Then, a semi-automatic procedure to detect association errors is applied.

Product

Since 2018, the CSI updates concern only the dataset of the integrated phases of the Italian networks and therefore the CSI as a catalog of absolute localizations has become CLASS 1.0, where locations are produced based on a probabilistic location method (NonLinLoc) in a 3D earth velocity model.
At present the CSI1.1/PHS integrated phase data-set has been updated to CSI2.0/phases (1981-2008) and is accessible through the top menù "Phases" of the present website, in a custom txt format. Under the top Menù voice "Stations" also the complete list of the seismic stations, with geographic coordinates, for the entire period (1981-2008 and beyond) is available. The catalog is accessible as yearly files phs format (similar to Hypo71 phs format) and each event phases association is labeled with the earthquake location parameters and ID of CLASS1.0 absolute location catalog.
Important note about the stations: the seismic stations evolved in time, both for what concerns the stations code and the affiliation network. Also, the geographic coordinates precision and error reduction changed in time. Thus different names/networks and slightly different coordinates can belong to a same seismic site. For this reason we decided to create the same alias for different codes in time a space with the leading condition that they are located within 500m from each other. Each line of the file reports the alias, the mean coordinates, standard deviation on lat, lon, elevations, the original station/network code and coordinates and, in some cases, the estimated google maps elevation for that stations.
The phases files and the stations file are fully compatible.