Spatial analysis for an evaluation of monitoring networks: examples from the Italian seismic and accelerometric networks

Marianna Siino,Antonino D’Alessandro,Salvatore Scudero,Luca Greco

doi:10.1007/s10950-020-09937-0

Marianna Siino, Antonino D’Alessandro + Show 2 more

Open Access

https://doi.org/10.1007/s10950-020-09937-0

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Abstract

In this work, we propose a statistical approach to evaluate the coverage of a network based on the spatial distribution of its nodes and the target information, including all those data related to the final objectives of the network itself. This statistical approach encompasses descriptive spatial statistics in combination with point pattern techniques. As case studies, we evaluate the spatial arrangements of the stations within the Italian National Seismic Network and the Italian Strong Motion Network. Seismic networks are essential tools for observing earthquakes and assessing seismic hazards, while strong motion (accelerometric) networks allow us to describe seismic shaking and to measure the expected effects on buildings and infrastructures. The capability of both networks is a function of an adequate number of optimally distributed stations. We compare the seismic network with the spatial distributions of historical and instrument seismicity and with the distribution of well-known seismogenic sources, and we compare the strong motion station distribution with seismic hazard maps and the population distribution. This simple and reliable methodological approach is able to provide quantitative information on the coverage of any type of network and is able to identify critical areas that require optimization and therefore address areas of future development.

Highlights

Country-scale seismic networks usually extend over an area of 105–106 km2 (D’Alessandro et al 2019) and, from planning to completion, can require several years to decades
We propose a statistical approach based on the spatial distribution of nodes within a large-scale network together with ancillary information related to the aims of the network itself
We cross-checked the distributions of the networks with the distributions of faults and seismicity

Summary

Introduction

Country-scale seismic networks usually extend over an area of 105–106 km (D’Alessandro et al 2019) and, from planning to completion, can require several years to decades. The final spatial distribution of the nodes can be remarkably different from the planned configuration for a multitude of reasons. The Italian National Seismic Network, (D’Alessandro et al 2011a, 2019) the Red Sısmica Nacional in Spain (D’Alessandro et al 2013), the Romanian network, and the Global Seismographic Network (GSN) took on average 20– 30 years (or more) to reach their present-day configuration, and they are still developing (Nacional and Rodrıguez 1995; Gee and Leith 2011; Popa et al 2015; Michelini et al 2016; D’Alessandro et al 2011b, 2012; D’Alessandro and Ruppert 2012; D’Alessandro and Stickney 2012). A network could be the result of the joining of different subnetworks. This is the case for the Hellenic Unified Seismological Network, which originated from four distinct networks, each of which developed independently in time and with partial spatial overlap (D’Alessandro et al 2011b). It is always beneficial to verify whether the distribution of nodes within a given network satisfies its final needs and objectives

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