Earthquakes of September-October 1997 in Umbria-Marche
(Central Italy)

Macroseismic data in terms of EM-92 scale



Introduction

After the earthquakes of 26 September 1997 in Central Italy, researchers of GNDT (National Group for Protection against Earthquakes), SSN (National Seismic Survey) and ING (National Institute of Geophysics) carried out macroseismic surveys, mostly devoted to supply the Department of Emergency Services with real time data on damage.
One of the big problems of this survey was the need of surveying the highest number of localities in the shortest possible time; therefore, intensities were assessed in terms of MCS intensity scales. Results can be found on this web.
The management of the surveys was complicated by the high number of damaging events which took place during about one month after September 26. Since the high number of damaged localities made practically impossible to repeat the intensity assessment after every strong earthquake, intensities are to be considered in most cases as cumulative.

However, for about 80 localities it was possible to spend some more time and answer questions related to the EM-92 intensity scale (Fig. 1). This special survey was performed in two phases: October 4 to 8 and 16 to 17, the second one after the 14 October, Sellano earthquake. Teams, based in Macerata (Osservatorio Geofisico), were composed by two to three persons, who filled in a very rough form designed on the spot. Data were later compiled in a digital format.
These data were not fully processed, yet; they were also kept restricted until recently in order to avoid conflicts related to the distribution of emergency funding. They are now proposed to European investigators as a tool for testing the EM-92 intensity scale and for discussing the practice of macroseismic survey.

Investigators are invited to process data and submit results and comments. A summary of the results will be presented at the XXIII EGS General Assembly, Nice, NH3, 23 April 1998.

Massimiliano Stucchi
(on behalf of the WG on EMS data of the 1997, Central Italy earthquakes)


Milano, March 1998

The survey was performed by: R. Azzaro, M.S. Barbano, R. Camassi, C. Carocci, V. Castelli, I. Cecic, S. Del Mese, P. Galli, I. Leschiutta, C. Meletti, D. Molin, G. Monachesi, G. Morelli, M. Onida, M. Stucchi, A. Tertulliani

 



 

Data

Data refer to 84 localities and 85 rows (the locality of Riofreddo was surveyed twice).
They are proposed in 44 columns, divided into 3 sections:

Section 1 - official data
   
N locality number
loc locality name
com name of the community to which the locality belongs
prov province code (MC = Macerata; PG = Perugia; AN = Ancona)
Lat, Lon locality co-ordinates
h locality altitude
in71 number of inhabitants (1971 census)
in91 number of inhabitants (1991 census)
date date of survey
op operator code (anonymous here)
   
   
Section 2 - data on damage (as reported by the operators)
   
TNB total number of buildings (according to the operator);
? points to figures which are in large contrast with in91
   
AB A-type buildings.
AT total number of buildings
Figures (S = single; F = few; M = many; Mo = most) are given for:
A0 number of buildings with damage of grade 0 (no damage)
A1 number of buildings with damage of grade 1
A2 number of buildings with damage of grade 2
A3 number of buildings with damage of grade 3
A4 number of buildings with damage of grade 4
A5 number of buildings with damage of grade 5
   
BB B-type buildings
(same as A)
   
CB C-type buildings
(same as A)
   
DB D-type buildings
(same as A)
   
   
Section 3 - data on objects and comments
   
SO reports on small objects
FU reports on furniture
   
Note: no answers to questions concerning effects on people(felt indoor, outdoor, frightened, awakened), on hanging objects, on china/glasses,
on doors
   
26.09/00.30 comments on the effects of the first earthquake
26.09/09.40 comments on the effects of the second earthquake
OTH comments on the effects of other earthquakes.
   
   
A further list of general comments follows in Section 4

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