In recent days, articles have appeared in various press organs that fear inefficiencies in the work of the National Institute of Geophysics and Volcanology (INGV) during the emergency in Ischia. In reality, the internal organizational machine and the analyzes conducted have been carried out and continue with the usual rigor and promptness. All the scientific products supplied in these days by INGV to the competent institutions fully comply with the qualitative requirements and the protocols established for the management of emergencies which represent the state of the art worldwide. INGV is the most important geophysical institution in Europe and is a national heritage with highly professional personnel and with a series of observational networks of inestimable value for the scientific community and citizens. Questioning its competence, impartiality and efficiency means not knowing how the institute works, fueling an unnecessarily specious controversy and unjustly damaging the image of a public research institution that works daily for seismic and volcanic surveillance in Italy .
As per the consolidated procedure formalized with the Civil Protection Department, INGV provides an estimate of the magnitude of any earthquake on the national territory greater than or equal to 2.5 (1.5 for Ischia and Campi Flegrei) within a few minutes of the seismic event. This procedure was also adopted on the evening of last August 21 when the seismic room of Rome, which receives the data recorded by over 400 seismic stations distributed throughout the country, detected an event in Ischia of Ml 3.6. This is called the local magnitude (Ml) and is a value which, although it may have an error of more or less than about 0.2, is still confirmed. The INGV operations room in Naples simultaneously processed the seismic recordings of the event and calculated with a different technique (magnitude duration, Md) estimating the earthquake at Md 4. INGV also communicated this new to the Civil Protection in real time given according to the procedures agreed with the same for volcanic areas. A subsequent estimate of the moment magnitude (Mw) confirmed M 4. All magnitude estimates greater than the latter are demonstrably unrealistic based on the data available to us.
Let's come to the location of the event: here too there are clear protocols that provide for an automatic evaluation and subsequent checks and progressive refinements. The times of emergency are not those of accurate scientific research which are necessarily longer.
In an emergency, the first estimate of the depth, made within 2 minutes in which the seismic room registers the shock, is always approximate. The second evaluation brought the event to a depth of about 5 km, 3 km north of Casamicciola. These are the estimates in the critical phase: however, aware of the importance of this information in a tragic event such as that of Ischia, the Authority immediately took steps to better locate the event (achieved in recent days and communicated on the morning of 25 August to the Major Risks Commission) which was raised about 2 km deep and inside the island.
INGV communicated the data and the calculations which were gradually elaborated in the most complete transparency and speed, not least the fundamental ones of the site effect detected; in fact, in addition to the superficiality of the hypocenter, the amplification of the waves played a fundamental role as they passed through soils with low seismic speeds, which even varied the acceleration of gravity by more than a quarter, causing the oscillations of the soil and the consequent damage to buildings, despite the relatively small magnitude.
Rome, August 26 2017
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