Appraising the Early-est earthquake monitoring system for tsunami alerting at the Italian Candidate Tsunami Service Provider

Abstract

Abstract. In this paper we present and discuss the performance of the procedure for earthquake location and characterization implemented in the Italian Candidate Tsunami Service Provider at the Istituto Nazionale di Geofisica e Vulcanologia (INGV) in Rome. Following the ICG/NEAMTWS guidelines, the first tsunami warning messages are based only on seismic information, i.e., epicenter location, hypocenter depth, and magnitude, which are automatically computed by the software Early-est. Early-est is a package for rapid location and seismic/tsunamigenic characterization of earthquakes. The Early-est software package operates using offline-event or continuous-real-time seismic waveform data to perform trace processing and picking, and, at a regular report interval, phase association, event detection, hypocenter location, and event characterization. Early-est also provides mb, M wp , and M wpd magnitude estimations. mb magnitudes are preferred for events with M wp 5.8, while M wpd estimations are valid for events with M wp 7.2. In this paper we present the earthquake parameters computed by Early-est between the beginning of March 2012 and the end of December 2014 on a global scale for events with magnitude M ≥ 5.5, and we also present the detection timeline. We compare the earthquake parameters automatically computed by Early-est with the same parameters listed in reference catalogs. Such reference catalogs are manually revised/verified by scientists. The goal of this work is to test the accuracy and reliability of the fully automatic locations provided by Early-est. In our analysis, the epicenter location, hypocenter depth and magnitude parameters do not differ significantly from the values in the reference catalogs. Both mb and M wp magnitudes show differences to the reference catalogs. We thus derived correction functions in order to minimize the differences and correct biases between our values and the ones from the reference catalogs. Correction of the M wp distance dependency is particularly relevant, since this magnitude refers to the larger and probably tsunamigenic earthquakes. M wp values at stations with epicentral distance 30• are significantly overestimated with respect to the CMT-global solutions, whereas M wp values at stations with epicentral distance 90• are slightly underestimated. After applying such distance correction the M wp provided by Early-est differs from CMT-global catalog values of about δM wp ≈ 0.0 ∓ 0.2. Early-est continuously acquires time-series data and updates the earthquake source parameters. Our analysis shows that the epicenter coordinates and the magnitude values converge within less than 10 min (5 min in the Mediterranean region) toward the stable values. Our analysis shows that we can compute M wp magnitudes that do not display short epicentral distance dependency overestimation, and we can provide robust and reliable earthquake source parameters to compile tsunami warning messages within less than 15 min after the event origin time.

Fast evaluation of tsunami scenarios: uncertainty assessment for a Mediterranean Sea database

“…These aspects will be better addressed in a future study that deals with the implementation of this tool for the Italian NEAMTWS Tsunami Service Provider (e.g. Bernardi et al, 2015).…”

Fast evaluation of tsunami scenarios: uncertainty assessment for a Mediterranean Sea database

“…In the presence of fast moment tensor solutions, the forecast uncertainty can be promptly reduced, while still incorporating errors in the real-time seismic solutions, by combining the latter with a-priori assumptions on the source mechanism probability. These aspects will be better addressed in a future study, dealing with the implementation of this tool for the Italian NEAMTWS candidate Tsunami Service Provider (e.g., Bernardi et al, 2015), and for supporting disaster response activities of the European Civil Protection Mechanism. Matplotlib (Hunter, 2007) tools.…”

The Italian National Seismic Network and the earthquake and tsunami monitoring and surveillance systems

“…The INGV seismic monitoring system provides prompt and reliable earthquake locations and magnitudes occurring in Italy and surrounding areas (Amato and Mele, 2008), and accurate estimates in the Mediterranean Basin and worldwide (Bernardi et al, 2015). The data recorded by the monitoring networks are transmitted in real-time to the operational rooms in Rome, Naples and Catania, where highly trained 24/7 staff analyze them to obtain the main parameters of the ongoing events and processes.…”

“…INGV receives real-time seismic data, recorded by about 400 stations distributed worldwide, through several institutions (GFZ, NOA, CENtre d'Alerte aux Tsunamis-CENALT, IRIS, NEIC, INGV). Seismic data are continuously and automatically analyzed by Early-Est, a software jointly developed by ALomax Scientific and INGV (Bernardi et al, 2015 and references therein; http://early-est.rm.ingv.it/warning. html) that performs seismic detection, location and magnitude estimation.…”