Starting today, INGV publishes the preliminary locations of earthquakes in real time on the @INGVterremoti Twitter channel, calculated automatically by the software of the Seismic Surveillance Room of Rome
The National Institute of Geophysics and Volcanology (INGV) now adopts a new way of communicating information on earthquakes through the Twitter channel @INGVterremoti.
In the event of a seismic event with a magnitude greater than 3, a tweet will automatically start a few minutes later with the estimate of the epicenter and the magnitude. The tweets will be launched only if the quality parameters indicate that the preliminary information will be sufficiently reliable and this information will be transmitted in the margin of the communication that the INGV Seismic Surveillance Room makes to the Civil Protection Department.
“The automatic location and magnitude”, explains Emanuele Casarotti, INGV researcher, “are calculated by the software without human intervention and are therefore subject to the uncertainties of the hypocentral coordinates and the magnitude inherent in the calculation system. To date, INGV has only communicated the location reviewed by the seismologists on duty in the Seismic Surveillance Room, an operation that requires up to 30 minutes of processing, on average about 10-12 minutes after the earthquake occurred. With this decision, in the event that an earthquake occurs, INGV intends to disseminate an initial indication of the epicentral area and magnitude as quickly as possible”.
The speed of the information can go to the detriment of its accuracy and some imprecision in the communication of the preliminary data will therefore be possible. For this reason, magnitude and epicenter will initially be communicated without indicating specific values, but providing a range of values for the magnitude, while as regards the epicenter, the province where it falls will initially be indicated (or the area if at sea or beyond beyond national borders).
"In the Seismic Surveillance Room of the INGV in Rome", explains Carlo Doglioni, President of INGV, "the signals arrive in real time, i.e. the seismograms, of the almost 400 stations of the National Seismic Network and of other networks that contribute to it . The signals are all digital and managed by dedicated software. When a certain minimum number of stations registers an earthquake, the computer systems used associate the signals with each other and try to calculate the hypocentral location and determine the magnitude".
During this operation, which can take 1 or 2 minutes, the goodness of the determination with qualitative parameters is also evaluated.
“At this point”, continues Emanuele Casarotti, “the seismologists begin reviewing the location and magnitude: they analyze the individual signals, verify that the software has worked correctly in identifying the arrival of the P waves and S waves and in calculating the maximum amplitudes. At the end of the review, the hypocentral position (latitude, longitude, depth) is recalculated and the magnitude re-estimated. Depending on the magnitude of the earthquake – and therefore the number of seismic stations that recorded it – and the geological complexities of the affected region, it can take up to 30 minutes to complete the review,” concludes the researcher.
The revised information is published on the website of the National Earthquake Observatory (ONT, http://cnt.rm.ingv.it/) and disseminated through the INGVterremoti social channels of Twitter and Facebook.
An example of a tweet for an autotracker is this:
[PROVISIONAL ESTIMATE] #earthquake Mag between 3.1 and 3.7, 17:54 IT of 25-08-2018, prov/zona Campobasso, #INGV_20497831
At the end of the revision by the shift workers, the definitive data will be made public with the indication [REVISED DATA]. The revision can concern both the position of the hypocenter (latitude, longitude, depth), and the magnitude.
An example tweet for the revised localization of the same event above is this:
[REVISED DATA] #earthquake ML 3.3 at 17:54 IT of 25-08-2018 at 4 km SE Montecilfone (CB) Prof=22Km #INGV_20497831
Rome, 4 September 2018
Example of the information contained in the two tweets for the same event. Above: first provisional estimate. Below: revised estimate after analysis by seismologists in the INGV seismic room. Note the time difference between the two tweets (about 11 minutes)
In-depth article on the INGVterremoti blog:
https://ingvterremoti.wordpress.com/2018/08/28/automatico
Link to Twitter channel @INGVterremoti:
https://twitter.com/INGVterremoti