Earthquake early warning system in southern Italy: Methodologies and performance evaluation

Abstract

[1] We investigate the effect of extended faulting processes and heterogeneous wave propagation on the early warning system capability to predict the peak ground velocity (PGV) from moderate to large earthquakes occurring in the southern Apennines (Italy). Simulated time histories at the early warning network have been used to retrieve early estimates of source parameters and to predict the PGV, following an evolutionary, probabilistic approach. The system performance is measured through the Effective Lead-Time (ELT), i.e., the time interval between the arrival of the first S-wave and the time at which the probability to observe the true PGV value within one standard deviation becomes stationary, and the Probability of Prediction Error (PPE), which provides a measure of PGV prediction error. The regional maps of ELT and PPE show a significant variability around the fault up to large distances, thus indicating that the system's capability to accurately predict the observed peak ground motion strongly depends on distance and azimuth from the fault.

Source parameter scaling and radiation efficiency of microearthquakes along the Irpinia fault zone in southern Apennines, Italy

“…A dense and high dynamic range, multicomponent seismic array, the Irpinia Seismic Network (ISNet) composed by 33 stations (Figure 1), has been recently deployed in the area for microseismicity monitoring and testing of a prototype system for earthquake early warning [Zollo et al, 2009]. All stations are equipped with a strong-motion accelerometer (Guralp CMG-5 T) and a three-component velocimeter (Geotech S-13 J), Depth (km) Depth (km) Figure 1.…”

Rapid Estimation of Earthquake Source and Ground-Motion Parameters for Earthquake Early Warning Using Data from a Single Three-Component Broadband or Strong-Motion Sensor

“…This procedure is problematic, because an adequate database containing the records of both moderate and large earthquakes over a wide range of source-to-site distances is unavailable for most seismic-active regions around the world, leading to large data gaps and thus uncertainties in the algorithms. Some authors have suggested filling these gaps with simulated waveforms (e.g., Zollo et al, 2009;Oth, Böse, et al, For each earthquake, we show the results at two stations at distinct epicentral distances Δ. From top to bottom the panels show the corresponding seismic records and results for classification (output should be 1 because Δ km ≤ 15M), magnitude M, peak ground velocity (PGV), and distance Δ.…”

The Status of Earthquake Early Warning around the World: An Introductory Overview

“…Still, EEW performance could be enhanced both in accuracy and warning times by integrating finite source detection methods (Heaton 1985;Allen 2006). Research is already underway using seismic methods to detect fault finiteness by assessing the proximity of stations to the fault and to map slip on the fault in real time (Yamada et al 2007;Yamada and Heaton 2008;Zollo et al 2009). Real-time geodetic data can currently offer accuracies at the subcentimeter level and could therefore provide constraints on these largemagnitude events as well (Crowell et al 2009, this issue).…”

“…The uncertainty in the EEW alerts has been modeled extensively and shows that the largest source of uncertainty in PGA estimates is the inherent uncertainty in the ground motion prediction equation and not the rapid magnitude and location estimates (Iervolino et al 2009). The performance of the system in large-magnitude events has also been studied and indicates a significant effect of source finiteness (Zollo et al 2009). …”

“…It may be sufficient to know that an event is M 6.5 or larger and broadcast a warning. However, methodologies to map the finite ruptures of these large (M > 7) earthquakes could also be developed and would enhance system performance (Yamada et al 2007;Yamada and Heaton 2008;Zollo et al 2009). …”