M=6.2 earthquake strikes central Italy, 35 km north of the disastrous 2009 M=6.3 L’Aquila event

Temblor

8 years ago

Ross Stein and Volkan Sevilgen, Temblor

Today’s earthquake, 10 km southeast of Norcia, has a shallow depth of 10 km, and lies in the Central Apennines normal faulting system. It was felt from Rome to Bologna. One can see from the Temblor map below that quakes of this size are expected one or two times in a lifetime at Norcia. In other words, a M=6 quake here as a little over a 1% chance of occurring per year. Fortunately, the epicenter does not lie at a major urban center, and so we are hopeful that casualties will not be high.

Temblor map of central Italy with today’s red quake pinned. The earthquakes shown are from the EMS catalog. The colors come from the Global Earthquake Activity Rate (GEAR) model of Bird et al. (2015), which is now displayed in the Temblor web app (app.temblor.net)

The 2009 M=6.3 L’Aquila quake struck just 35 km to the south in the Abruzzo. The L’Aquila mainshock struck just 5 km from the town. The quake took 308 lives and destroyed the central business district and most of the treasured historical buildings that distinguished the town. Despite its modest size, L’Aquila proved to be the deadliest earthquake in Italy since the much larger M=6.9 1980 Irpinia shock.

USGS map of earthquakes over the past decade. The large white dot to the SW of ‘L’Aquila’ is the 2009 M=6.3 mainshock; the surrounding white dots are its aftershocks.

The aftershock zone is about 20 km long and the focal mechanism is for a tensional (“normal”) rupture on a fault striking northwest consistent with the Apennine ranges.

Data from USGS, INGV (Istituto Nazionale di Geofisica e Volcanologia) and EMSC (European‑Mediterranean Seismological Centre)

You can check the aftershocks here.