AMQ32(2) 93-100 Galli Pallone.pub REVIEWING THE INTENSITY DISTRIBUTION OF THE 1933 EARTHQUAKE (MAIELLA, CENTRAL ITALY). CLUES ON THE SEISMOGENIC FAULT Paolo Galli 1, Francesca Pallone 2 1 Dipartimento della Protezione Civile, Roma, Italy. 2 ANAS SpA Roma, Italy. Corresponding author: P. Galli ABSTRACT: Here we deal with the study of a strong earthquake occurred in 1933 in the mountainous area of the Maiella massif (Abruzzi, central Italian Apennines). We carried out original archive researches that allowed to evaluate a novel macroseismic field, and new parameters for this earthquake (Io=Imax 9 MCS; Mw 6.01±0.07; epicentral coordinate: N42.050°, E14.191°). Then we compared its highest intensity distribution of this event with the known, active normal fault of the region, finding any possible matching with none of these. Therefore, considering the subsurface tectonic interpretation provided by the recent scientific literatu- re, we hypothesize that a possible seismogenic structure for both the 1933, and the catastrophic 1706 event (Mw 6.9; roughly same 1933 epicenter) is the blind backthrust that developed during Early-Middle Pleistocene in the footwall of the Maiella anticline. Keywords: 1933 earthquake; macroseismology; compressive tectonics; Maiella massif. Available online http://amq.aiqua.it ISSN (print): 2279-7327, ISSN (online): 2279-7335 Alpine and Mediterranean Quaternary, 32 (2), 2019, 93 - 100 1. INTRODUCTION At dawn of September 26 1933 (4:33 local time, 3:33 GMT) a strong earthquake struck the southeastern area of the Maiella massif (Abruzzo, central Italian Ap- ennines), damaging heavily several villages, and caus- ing extensive destruction in few localities, as in Lama dei Peligni, Taranta Peligna, and Civitella Messer Rai- mondo. The mainshock was closely preceded by two foreshocks that - alarming the inhabitants of the region - prompted most of them to escape from their houses, and to pass the night outsides their fragile, old stone- masonry houses. Therefore, in spite of the large amount of collapses and destructions (Fig. 1), this yielded a relatively little death toll (12 casualties), and less than two hundred injured. Two centuries before, in 1706, the same region was hit by one of the strongest and deathful earthquake in the Italian history (Io 10.5; Mw=6.8. More than 2200 victims). Interestingly, the two events share a similar mesoseismic area, the older presenting much higher site intensities. Although the seismogenic sources of both earthquakes have remained unknown so far, giving the similarity of the respective Highest Intensity Data- points Distribution (HIDD), it is possible that they could share segments of the same fault system. In order to enhance the knowledge concerning the highest intensity distribution (Is≥ 7 MCS) of the 1933 earthquake, and thus indirectly enlighten the rough loca- tion of its causative fault (and hopefully the 1706 one), here we carried out a reappraisal of all the data quoted or reported in the Italian seismic databases (e.g., DBMI15, 2016; CFTI5Med, 2018; ASMI, 2019). As the previous studies were mainly based upon the infor- mation listed in few newspapers and on the works of Cavasino (1935a; 1935b) and Margottini et al. (1992), we also performed farther archive and library researches that allowed us to collect new, original and reliable data. 2. MATERIALS AND METHODS With the aim of completing the information con- cerning the damage within each municipality, firstly we carried out an extensive reading of contemporary peri- odical publications at the Central National Library of Rome, where we collected useful information reported inside 15 Italian newspapers (i.e., Il Mattino; Il Giornale d’Italia; La Nazione; Il Popolo d’Italia; Il Popolo di Roma; Il Regime Fascista; il Corriere della Sera; La Tribuna; l’Osservatore Romano; la Gazzetta del Popolo; Roma; L’Avvenire d’Italia; il Lavoro Fascista; il Tevere; il Mes- saggero), for a total of 58 articles specifically dealing with the earthquake. We also found generic information on French papers at the National Library of France (Paris), as in Le Journal, Le Populaire and L'Ouest- Éclair. Although newspapers contain first-hand news and accounts, we have found that the information were often qualitative, reporting just the number of victims in each village, the number of injured people, and a rough https://doi.org/10.26382/AMQ.2019.05 94 Galli P. & Pallone F. framework of the destroyed houses and of those still inhabitable. It is worth noting that, similarly to what hap- pened three years before after the so-called Vulture earthquake (July 23, 1930; Mw 6.7, southern Italian Apennines. See Castenetto & Sebastiano, 2002), Italian press-reporters widely emphasized the prompt rescue and assistance provided to the inhabitants by the Fas- cist government and by the local authorities. And then, as in 1930, in spite of the severe damage scenario, the whole national press suddenly minimized the event, which soon disappeared from all the newspapers pages. The spirit of the times is well condensed in a telegram, sent on October 1 by the Italian Prime Minister to the Minister of the Public Works, which just says: "Go for a ride in the earthquake zone - Mussolini", clearly implying to minimize anything (Fig. 2). We also made researches inside the former ar- chive of the Civil Protection Department where - besides a large amount of telegrams sent by the Prefects to the Interior Ministry, mostly containing the early news on the earthquake effects - we have found an enormous quan- tity of documents attesting the requests of economical support sent by each single citizens, their associated technical expertise, and, sometime, the answers provid- ed by the authorities in the following months or years. Most of this information supported the evaluation of the level of damage existing in each locality, providing also complementary data in places not fully covered by other sources. Nevertheless, one of the most important and novel data in our study derives from the huge mass of infor- mation collected by Ridolfi (2005), who was previously ignored in any seismic compilation. Her work is entirely devoted to the effects that the 1933 earthquake had on the region surrounding the Maiella massif (Abruzzo side). Data were mainly collected in archives and librar- ies, such as: Central State Archive; State Archive of Chieti; State Archive of Pescara; historical archive of Banco di Napoli; historical Archive of the municipality of Avezzano; archive of the Superintendency of Public Works; Library of the Chamber of Deputies; Library of the Ministry of Agriculture; Library of the Bank of Italy; archive of the Chamber of Commerce, Industry, Agricul- ture and Crafts of Chieti. By ordering and systematizing all of these huge amount of valuable information, it was possible to pre- cisely estimate the number of building affected by each specific damage level (e.g., light, moderate and severe damage, destruction, collapse), and thus evaluate the intensity degree according to the Mercalli-Cancani- Sieberg (MCS) scale, published just three years before by Sieberg (1930). As explained in the following, to do Fig. 1 - View of the collapse of some poor stone-masonry houses in a village east of the Maiella Massif (left; L’Illustrazione Italiana, 1933) and in Lama dei Peligni (right; photo Keystone-France/Abruzzes/gettyimages). Fig. 2 - The telegram sent by Benito Mussolini to Araldo di Crollalanza, Minister of the Public Works: “Go for a ride in the earthquake zone”. It is quite clear the intent to minimize the effects of the earthquake. (Civil Protection Department Archive). 95 Reviewing the intensity distribution of the 1933 earthquake (Maiella, central Italy) this, we analytically applied the method suggested by Molin (2009), that considers the percentage of each damage level (1-5) as representative of every MCS degree (from 5 to 11 MCS). 3. RESULTS First of all, for each singe locality, we obtained the percentage of buildings affected by the different levels of damage that we mainly deduced from the analytical data contained in the Ridolfi’s (2005) work, filling the gaps with information collected from newspapers, tele- grams and other primary sources found in the archive of the Civil Protection Department. Then we transformed these percentages in MCS degree, considering damage levels 2-3 (i.e., from moderate to severe damage, not distinguishable singularly in most of the documentary materials), 4 (destruction, and/or irreparable damage), and 5 (collapse) in the percentage progression pro- posed by Molin (2009). This allowed us to obtain robust intensities estimates (see Tab. 1) that generally move away from those reported in DBMI15 (2016) and CFTI5Med (2018) by just 0.5-1 degrees or, exceptional- ly, 1.5 degree. It is worth noting that in the previous studies many intensity datapoints were derived uncritically from a crude list published by Cavasino (1935b), who likely estimated the MCS intensities on the basis of the fresh information gathered brevi manu from the local authori- ties of the time, leaving any written description of the effects felt by these localities. Therefore, in order to complete the dataset of our datapoints - that mainly lacks the lowermost intensities - we also decided to consider those published by Cavasino (1935b). Howev- er, before including tout court these intensities, we com- pared analytically our intensities with those in Cavasino (1935b), calculating thus a linear regression between the two datasets. Then, by applying the resulting equa- tion, we obtained a Is value for the lacking intensities consistent with our macroseismic evaluation (Tab. 1). The new areal distribution of the highest intensity datapoints (Fig. 3, left) provides a slightly different image of the mesoseismic area then before, although it re- mains strongly focused on the Maiella massif, with a macroseismic epicenter (black rhomb in Fig. 3) falling close to Lama dei Peligni. This epicenter falls ~7 km away from that calculated by Palombo (2010) by using the time arrivals of P and S-wave phases reported in the ISS bulletins, and coupled with the NonLinLoc code (Lomax et al., 2000), with this point assumed as the maximum likelihood instrumental location for the 1933 earthquake. The epicentral intensity can be evaluated around Io 9 MCS, as in CPTI15 (2016) and CFT5Med (2018), with coordinates of N42.050°, E14.191°. In turn, the equiva- lent magnitude that we have calculated by applying BOXER4 algorithm (Gasperini et al., 1999) is Mw 6.01±0.07 (5.9±0.07 in CPTI15; 6.05±0.1 in CFT5Med; 6.4±0.3 in Palombo, 2010), with a source length of 13 km striking N30°±13°, that is perpendicular and external to all the main extensional, NW-SE active fault of central Apennines (Fig. 3). Last but not least, we have found a novel and inter- esting information concerning surface effects produced by the earthquake. This regards the damage suffered by a tunnel of the Sulmona-Roccaraso line, that caused the stop of the trains between the stations of Campo di Giove and Palena (green circle in Fig. 4) Fig. 3 - Left, distribution of the highest intensities distribution re-evaluated here for the 1933 earthquake (yellow circles proportional to Is 5- 9 MCS). Background colors suggest the areal distribution of the intensities (see MCS scale; kriging interpolation); black rhomb is the mac- roseismic epicenter calculated through Boxer4 algorithm (Gasperini et al., 1999); red rhomb is the instrumental epicenter (Palombo, 2010). Right, same image for the 1706 earthquake (unpublished data of the authors); black rhomb is the 1706 macroseismic epicenter (Boxer4 algorithm); red rhomb is again the 1933 instrumental epicenter. Blue lines in both panels are the normal active faults of the region, all SW dipping (mod. From Galli & Peronace, 2014). Note that intensities span between 7-11 MCS in the 1706 panel vs 5-9 MCS in the 1933 panel. 96 Tab. 1 - MCS intensities (Is) related to the 26 September 1933 mainshock. Lon and Lat are WGS84 geographic coordinate of centroid of locality. Galli P. & Pallone F. 4. DISCUSSION AND CONCLUSIONS Observing the left panel of Fig. 3, we notice that the highest site intensities of the 1933 earthquake fall at the base of the eastern edge of the Maiella massif (i.e., Taranta dei Peligni, Lama dei Peligni, and Civitella Mes- ser Raimondo, all with Is 9 MCS; see Tab. 1), decreas- ing then progressively eastward and northward. Intensi- ties 7-8 MCS also characterize the eastern flank of the Morrone ridge, with a peak of Is 8.5 MCS in Salle Vec- chia, where diffuse landsliding, more than shaking, con- tributed to the severe damage framework. Obviously, the lack of localities in the mountainous zones of the 97 Maiella massif alters the perception of the real shaking distribution, although it is clear that the strongest ground acceleration is confined in the Adriatic side of the Morro- ne-Maiella ridge. Definitively, this means that none of the ~west dip- ping active normal faults of the region (i.e., all the blue lines in Fig. 3 - 4) can be the source of this earthquake. Indeed, the 1933 HIDD is fully concentrated in the foot- wall of these structures, in contrast to all the earth- quakes of the Italian Apennines, the HIDD of which fall always in the hangingwall of their causative faults (e.g. in Galli & Galadini, 1999; Galli et al., 2009; 2017). As far as the possible 1933 and 1706 sources are Fig. 4 - A, shaded relief map of central Apennines with the major historical seismicity (red circles, Mw>5.0; yellow circles, well-dated Mw>6.5 paleoseismological events; Galli et al., 2015; 2016) and the main, active normal faults (blue lines; mod. from Galli and Peronace, 2014). MFS, Mount Morrone fault system; CF, Caramanico fault. Red rhomb is the 1933 instrumental epicenter (Palombo, 2010). Red triangles-dashed lines suggest the bounding thrust of the Casoli-Bomba (C-B) pop-up and of the buried backthrust below the Maiella anti- cline footwall (MAFB; inferred northward mimicking the Caramanico fault path; Ghisetti and Vezzani, 2002; Calamita et al., 2009). Dotted line is the segment of CROP-11 line shown in panel B; green circle indicates the area where the railway tunnel was damaged by the 1933 earthquake. B, part of CROP-11 line interpreted by Patacca et al. (2008). 1, Pleistocene marine deposits of the foredeep basin; 2, Pliocene marine deposits conformably overlying the Apulia carbonates; 3, Mount Genzana unit; 4, Mount Morrone-Porrara unit; 5, Upper Cretaceous -Pliocene Mount Queglia unit; 6, Molise units; 7, Lower Pliocene flysch of Maiella unit; 8, Mesozoic-Tertiary carbonates of Maiella unit; 9, Mesozoic-Tertiary carbonates of Apulia Platform; 10, Paleozoic-Triassic deposits. Reviewing the intensity distribution of the 1933 earthquake (Maiella, central Italy) concerned, some authors associated these earthquakes to two consecutive ruptures of patches of a so-called, SW-dipping Abruzzo Citeriore Basal Thrust (Lavecchia & de Nardis, 2010). However, the existence of this Ba- sal Thrust is denied by the interpretation provided by Patacca et al. (2008) of the CROP 11 deep reflection seismic profile, where the entire Pliocene Maiella ramp- anticline overlies a popup structure in the Mesozoic- Tertiary carbonates of the Apulia Platform. This popup is instead related to an important E-dipping backthrust (MAFB in Fig. 4; Patacca et al., 2008), which likely con- trolled also the growth of the neighboring Casoli-Bomba high (C-B pop-up in Fig. 4). According to Patacca et al. (2008), the existence, timing and importance of this blind structure, which de- veloped in the footwall of the Maiella anticline, is testi- fied also by the impressive uplift of the Maiella anticline just over the backthrust hanging-wall. The uplift started in the Early Pleistocene, rising the top of the Maiella carbonate massif at a rate of some centimeters per year (i.e., vertical component of the active-thrust slip vector), from few hundred meters a.s.l. to the present elevation (~2800 m), or more. Another evidence for this is the > 3500 m vertical throw accommodated by the Caraman- ico normal fault (CF in Fig. 4B; see also Ghisetti & Vez- zani, 2002), which could represent a gravity collapse feature developed in the roof of the passively growing Maiella tectonic edifice (Patacca et al., 2008). If this interpretation is correct, as the HIDD of the 1706 and 1933 earthquakes mainly fall in the broad hanging-wall of this backthrust, one could hypothesize that both events were sourced by a residual activity of this Quaternary structure that, tentatively, could also trigger the passive motion of the Caramanico fault. Like- wise, also other earthquakes occurred in the farther, backthrust hanging-wall, as the 1881 one (Mw 5.4; Fig. 4A), could have been sourced by structures rooted at depth to the sole thrust, for instance those bounding the Casoli-Bomba high (Fig. 4B). Nevertheless, whereas the largest slip of the back- thrust occurred during the late Emilian-early Sicilian (Patacca et al., 2008), today we have not geological evidence for such a persisting activity in its hanging- wall, with the exception of some morphotectonic indica- tion suggesting post-Middle Pleistocene anticline grow- ing (Pomposo & Pizzi, 2009). Even the geodetic data published so far (D’Agostino et al., 2011; D’Agostino, 2014; Angelica et al. 2013; Devoti et al., 2011; Galvani et al., 2012) show that the outer Morrone-Maiella region is not experiencing NE-SW compression, as GPS vec- tors located westward and eastward of these massifs roughly show the same NE velocity. Moreover, there are neither focal mechanisms, nor borehole breakouts in the whole region supporting or ruling out ongoing compres- sion (e.g. in Mariucci & Montone, 2018). Actually, Palombo (2010) tried to calculate the 1933 focal mechanism from eighteen retrieved paper- seismograms, although only eight had useful P wave first motion. Amongst the possible solutions, Palombo (2010) evidenced two groups with different kinematics; one with average NW-SE trend associate to a NE-SW tensional axis (i.e., transtensive NE-SW faults), and the other compatible with a NE-SW compressive field (NNE- SSW, transpressive, right strike-slip fault, i.e., similar to the strike of the source resulting from the Boxer4 algo- rithm). Honestly, at the moment, we can conclude that the seismogenic sources of these two frightful earthquake are still uncertain. We can surely exclude that they were generated by any of the known, active normal faults mapped in Fig. 4, and least of all by the Mount Morrone fault system which bounds the eastern side of the Sul- mona basin (MFS in Fig. 4A). As aforementioned, the HIDD of the 1706 and 1933 events fall in the footwall of all these faults, while the Mount Morrone fault, although very close to both epicenters, and partly running inside the 1706 HIDD, sourced its last earthquake in the far 2nd century AD, as definitely demonstrated by recent paleo- seismic studied (Galli et al., 2015). Concluding, our working hypothesis - which makes no claims to being conclusive - is that the source of both 1706 and 1933 events might be the blind backthrust in the footwall of the Maiella anticline, the geometry of which matches the HIDD of both events. In this case, it is also possible that the Caramanico fault might move passively, inducing some surface rupture, as suggested by the damage in the railway tunnel in 1933. All this implies the existence of active, NE-SW compression just east to the extensional belt highlighted by the active faults shown in Fig. 4B, which is not (yet?) adequately supported by either geological or instrumental data. ACKNOWLEDGMENTS We are grateful to N. Ridolfi who share with us the results of her long work. We thank D. Molin for the use- ful discussion, and the personal of the Archive of the Dipartimento della Protezione Civile Nazionale of Italy who supported our research. P. Messina and E. Pero- nace provided useful criticism in reviewing the manu- script. The views and conclusions contained here are those of the authors and should not be interpreted as necessarily representing official policies, either ex- pressed or implied, of the Italian Government. REFERENCES ASMI (2019) - Archivio Storico Macrosismico Italiano, Rovida A., Locati M., Antonucci A., Camassi R. (eds.), Istituto Nazionale di Geofisica e Vulcanolo- gia, https://emidius.mi.ingv.it/ASMI/ Calamita F., Esestime P., Paltrinieri W., Scisciani V., Tavarnelli E. (2009) - Structural inheritance of pre- and syn-orogenic normal faults on the arcuate geometry of Pliocene-Quaternary thrusts: Exam- ples from the Central and Southern Apennine Chain, Ital.J.Geosci, 128, 381-394. Castenetto S., Sebastiano M. (2002) - Il regime fascista e le calamità naturali, in: Il terremoto del Vulture del 23 Luglio 1930, Roma, 49-58. Cavasino A. (1935a) - I terremoti d’Italia nel trentacin- quennio 1899-1933, in "Memorie del Regio Ufficio Centrale di Meteorologia e Geofisica", s. III, ap- pendice al vol.4. Roma 1935. Cavasino A. (1935b) - Bollettino sismico anno 1933, fasc.2 (Macrosismi), Regio Ufficio Centrale di Me- teorologia e Geofisica. Roma 1935. 98 Galli P. & Pallone F. central Italy in 1400 years evidenced by new pa- laeoseismic results, Terra Nova, 28, 146-154. Galvani A., Anzidei M., Devoti R., Esposito A., Pietranto- nio G., Pisani A.R., Riguzzi F., Serpelloni E. (2012) - The interseismic velocity field of the central Apennines from a dense GPS network, Annals of Geophysics, 55, doi: 10.4401/ag-5634. Gasperini P., Bernardini F., Valensise G., Boschi E. (1999) - Defining seismogenic sources from histo- rical felt reports, Bull. Seism Soc. Am., 89, 94-110. Ghisetti F., Vezzani L. (2002). Normal faulting, extension and uplift in the outer thrust belt of the central Apennines (Italy): role of the Caramanico fault, Basin Research, 14, 225-236. Lavecchia G., de Nardis R. (2010) - Seismogenic sour- ces of major earthquakes of the Maiella area (central Italy): constraints from macroseimic field simulations and regional seimotectonics. UR 4.01, DPC-INGV project 2007-2009. Lomax A., Virieux J., Volant P. and Berge C (2000) - Probabilistic earthquake location in 3D and layered models: Introduction of a Metropolis-Gibbs method and comparison with linear locations, in Advances in Seismic Event Location Thurber, C.H., and N. Rabinowitz (eds.), Kluwer, Amsterdam, 101-134. Margottini C., Puglisi C., Sericola A. (1992) - Il terremo- to del 1933 nell'area della Maiella (Abruzzo-Italia Centrale). ENEA, rapporto interno, Roma, 24 pp. Mariucci M.T., Montone P. (2018) - IPSI 1.2, Database of Italian Present-day Stress Indicators, Istituto Nazionale di Geofisica e Vulcanologia (INGV). Doi: 10.6092/INGV.IT-IPSI.1.2 Molin D. (2009) - Rilievo macrosismico in emergenza. Rapporto interno Dipartimento della Protezione Civile; Ufficio III Valutazione, prevenzione e mitiga- zione del rischio sismico, internal report. Patacca E., P. Scandone E. Di Luzio G. P. Cavinato and M. Parotto (2008) - Structural architecture of the central Apennines: Interpretation of the CROP 11 seismic profile from the Adriatic coast to the oro- graphic divide, Tectonics, 27, TC3006. Doi:10.1029/2005TC001917 Palombo B. (2010) - Information on Source parameters of meaningful Italian historical earthquakes estima- ted within the SISMOS project framework, Task B of UR 4.02, DPC-INGV project 2007-2009. Pomposo G., Pizzi A. (2009) - Evidenze di tettonica recente ed attiva nel settore sepolto dell’Appenni- no Abruzzese, Rendiconti della Società Geologica Italiana, 5, 176-178. Ridolfi N. (2005) - Economia di una catastrofe: il terre- moto della Majella in epoca fascista. Collana del Dipartimento di Economia e Storia del Territorio. Università "G. D'Annunzio" di Chieti-Pescara - F. Angeli. Sieberg A. (1930) - Geologie der Erdbeben. Handboch der Geophysic, 2, 4, 552-554 [Tabb. 100, 101, 102, 103], Berlin. NEWSPAPERS Corriere della Sera, 27-28-29-30/09/1933, Milano 1933. Il Giornale d’Italia, 27-28/09/1933; 5-6/10/1933, Roma CFTI5Med (2018) - Catalogo dei Forti Terremoti in Italia (461 a.C.-1997) e nell’area Mediterranea (760 a.C. -1500), E. Guidoboni, G. Ferrari, D. Mariotti, A. Comastri, G. Tarabusi, G. Sgattoni, G. Valensise (eds.), Istituto Nazionale di Geofisica e Vulcanolo- gia. http://storing.ingv.it/cfti/cfti5/. Doi: 10.6092/ingv.it-cfti5 CPTI15 (2016) - The 2015 version of the Parametric Catalogue of Italian Earthquakes, Rovida A., Loca- ti M., Camassi R., Lolli B., Gasperini P. (eds), Isti- tuto Nazionale di Geofisica e Vulcanologia. https:// emidius.mi.ingv.it/CPTI15-DBMI15/. Doi: 10.6092/INGV.IT-CPTI15 D’Agostino N. (2014) - Complete seismic release of tectonic strain and earthquake recurrence in the Apennines (Italy), Geophys. Res. Lett. 41. Doi: 10.1002/2014GL059230 D'Agostino N., Mantenuto S., D'Anastasio E., Giuliani R., Mattone M., Calcaterra S., Gambino P., Bonci L. (2011) - Evidence for localized active extension in the central Apennines (Italy) from global positio- ning system observations. Geology, 39, 291-294. Doi:10.1130/G31796.1 DBMI15 (2016) - The 2015 version of the Italian Macro- seismic Database, Locati, M., Camassi R., Rovida A., Ercolani E., Bernardini F., Castelli V., Caraccio- lo C.H., Tertulliani A., Rossi A., Azzaro R., D’Ami- co S., Conte S., Rocchetti E. (eds.), Istituto Nazio- nale di Geofisica e Vulcanologia. https:// emidius.mi.ingv.it/DBMI04/. Doi: 10.6092/INGV.IT-DBMI15 Devoti R., Esposito A., Pietrantonio G., Pisani A.R., Riguzzi F. (2011) - Evidence of large scale defor- mation patterns from GPS data in the Italian sub- duction boundary. Earth and Planetary Science Letters 311 (3-4), 1-12. Doi: 10.1016/j.epsl.2011.09.034 Galli P., Galadini F. (1999) - Seismotectonic framework of the 1997-98 Umbria-Marche (Central Italy) ear- thquakes. Seismological Res. Letters, 70, 4, 404- 414. Galli P., Camassi R., Azzaro R., Bernardini F., Castenet- to S., Molin D., Peronace E., Rossi A., Vecchi M., Tertulliani A. (2009) - Il terremoto aquilano del 6 aprile 2009: rilievo macrosismico, effetti di superfi- cie ed implicazioni sismotettoniche. Il Quaternario, 22, 235-246. Galli P., Castenetto S., Peronace E. (2017) - The macro- seismic intensity distribution of the 30 October 2016 earthquake in central Italy (Mw 6.6): Seismo- tectonic implications. Tectonics, 36. 1-13. Doi: 10.1002/2017TC00458. Galli P., Peronace E. (2014) - New paleoseismic data from the Irpinia Fault. A different seismogenic per- spective for southern Apennines (Italy), Earth- Science Reviews, 136, 175-201. Galli P., Giaccio B., Peronace E., Messina P. (2015) - Holocene Paleoearthquakes and Early-Late Plei- stocene Slip-Rate on the Sulmona Fault (Central Apeninnes, Italy), Bull. Seism. Soc. Am., 105(1), 1- 13. Galli P., Giaccio B., Messina P., Peronace E. (2016) - Three magnitude 7 earthquakes on a single fault in 99 Reviewing the intensity distribution of the 1933 earthquake (Maiella, central Italy) 100 1933. Il Lavoro Fascista, 27- 29/09/1933; 1/10/1933, Milano 1933. Il Mattino, 27-29/09/1933; 5/10/1933, Napoli 1933. Il Messaggero, 27-28-29/09/1933, Roma 1933. Il Popolo d’Italia, 27-28/09/1933; 1-4/10/1933, Milano 1933. Il Popolo di Roma, 27-29/09/1933, Roma 1933. Il Regime Fascista, 27-28/09/1933; 4/11/1933, Cremona 1933. Il Tevere, 27-29-30/09/1933; 4-5-26/10/1933; 6-24/11/ 1933, Roma 1933. L’Avvenire d’Italia , 27/09/1933; 1/10/1933; 24/11/1933, Bologna 1933. L’Osservatore Romano, 27-28-29/09/1933; 24/11/1933, Città del Vaticano 1933. La Gazzetta del Popolo, 27-28-29-30/09/1933, Torino 1933 La Nazione, 27-29/09/1933, Firenze 1933. La Tribuna, 27-28-29-30/09/1933; 24/11/1933, Roma 1933. Roma, 27-28-30/09/1933; 1-3-24/11/1933, Roma 1933. Le Journal, 27/09/1933, Paris, 1933. Le Populaire, 27/09/1933, Paris, 1933. L'Ouest-Éclair, 27-28/09/1933, Paris, 1933. Galli P. & Pallone F. Ms. received: February 19, 2019 Final text received: March 20, 2019