scholarly journals The May 2012 Emilia (Italy) earthquakes: preliminary interpretations on the seismogenic source and the origin of the coseismic ground effects

2012 ◽  
Vol 55 (4) ◽  
Author(s):  
Alberto Pizzi ◽  
Vittorio Scisciani
Keyword(s):  
Seismic Reflection ◽  
Field Survey ◽  
Epicentral Distance ◽  
Northern Italy ◽  
Seismic Reflection Profile ◽  
Epicentral Area ◽  
Preliminary Model ◽  
Seismogenic Source ◽  
Emilia Romagna Region ◽  
Ground Effects

<p>On May 20, 2012, a Ml 5.9 earthquake (T1) occurred in the Emilia-Romagna Region of northern Italy. This was preceded by a Ml 4.1 foreshock on May 19, 2012, and followed by several aftershocks, including two Ml 5.1 events, both on the same day. On May 29, 2012, a second strong event of Ml 5.8 (T2) hit the same region, with its epicenter ca. 12 km to the WSW of the first mainshock, T1. The epicentral area of the seismic sequence covers an alluvial lowland that is occupied by both agricultural and urbanized areas, and there were 17 casualties and about 14,000 people left homeless. […] In the present study, we provide a preliminary model of the seismogenic source(s) responsible for the two mainshocks, by comparing the seismic reflection profile interpretation with the available seismological and interferometric data. Furthermore, we show the coseismic ground effects that were observed in the epicentral area during two field survey campaigns: the first conducted after the May 20, 2012, event and the second soon after the May 29, 2012, earthquake, when several sites were revisited to observe the occurrence of newly formed or 're-activated' liquefaction features. Hence, we discuss the origin and location of the coseismic features observed in the context of the local geological–geomorphological setting and with respect to the epicentral distance. Finally, we provide our interpretation for the question: "Why did the mainshock ruptures not break the surface?" […]</p><p><strong> </strong></p> <p><strong> </strong></p>

scholarly journals Searching for the effects of the May-June 2012 Emilia seismic sequence (northern Italy): medium-depth deformation structures at the periphery of the epicentral area

2012 ◽  
Vol 55 (4) ◽  
Author(s):  
Lisa Borgatti ◽  
Antonio Edoardo Bracci ◽  
Stefano Cremonini ◽  
Giovanni Martinelli
Keyword(s):  
Ground Level ◽  
Northern Italy ◽  
Seismic Sequence ◽  
Surface Phenomena ◽  
Po River ◽  
Epicentral Area ◽  
Ground Fissures ◽  
Groundwater Levels ◽  
Geological Surveys ◽  
Emilia Romagna Region

<p>In 2012, a seismic sequence occurred in the lowlands of the Emilia-Romagna Region (northern Italy), between the borders of the Modena, Ferrara and Bologna Provinces. It consisted of seven mainshocks (5.9 &gt; Ml &gt; 5) that were recorded between May 20 and 29, 2012 [INGV 2012a] and 2,200 minor earthquakes [INGV 2012b]. An interferometric analysis [Bignami et al. 2012, Salvi et al. 2012, this volume] highlighted three main deformation areas, each of which was 12 km wide (from S to N) and 10 km to 20 km long in an ESE-WNW to E-W direction, thus affecting an area of about 600 km2 (Figure 1). Field and aerial geological surveys recorded numerous surficial effects, such as: (i) sediment liquefaction [Crespellani et al. 2012]; (ii) localized ground fissures resembling surficial faulting [Fioravante and Giretti 2012] (Figure 2); (iii) groundwater levels rising up to 400 cm above the local ground level in phreatic wells during the mainshocks (lower values were observed in confined aquifers); and (iv) dormancy of previously known sinkholes [Borgatti et al. 2010, Cremonini 2010a, and references therein]. Some of the observed surface phenomena were previously recorded as coseismic effects during the earthquakes of Ferrara (1570) and Argenta (1624) [Boschi et al. 1995, Galli 2000], together with the early rising of the water level of the Po River in the Stellata section. […]</p>

Synthetic seismic reflection profile through the Ivrea zone–Serie dei Laghi continental crustal section, northwestern Italy

Geology ◽  
1999 ◽  
Vol 27 (1) ◽  
pp. 79 ◽  
Author(s):  
Ernest H. Rutter ◽  
Jalal Khazanehdari ◽  
Katharine H. Brodie ◽  
Derek J. Blundell ◽  
David A. Waltham
Keyword(s):  
Seismic Reflection ◽  
Seismic Reflection Profile ◽  
Reflection Profile ◽  
Ivrea Zone

Active fault-related folding in the epicentral area of the December 25, 1222 (Io=IX MCS) Brescia earthquake (Northern Italy): Seismotectonic implications

2009 ◽  
Vol 476 (1-2) ◽  
pp. 320-335 ◽  
Author(s):  
Franz A. Livio ◽  
Andrea Berlusconi ◽  
Alessandro M. Michetti ◽  
Giancanio Sileo ◽  
Andrea Zerboni ◽  
...  
Keyword(s):  
Active Fault ◽  
Northern Italy ◽  
Epicentral Area

Interpretation of seismic reflection profiling data for the structure of the San Andreas fault zone

1983 ◽  
Vol 73 (6A) ◽  
pp. 1701-1720
Author(s):  
R. Feng ◽  
T. V. McEvilly
Keyword(s):  
Fault Zone ◽  
Seismic Reflection ◽  
San Andreas Fault ◽  
Velocity Model ◽  
Seismic Reflection Profile ◽  
Lateral Velocity ◽  
Zone Structure ◽  
Ray Method ◽  
Velocity Change ◽  
San Andreas

Abstract A seismic reflection profile crossing the San Andreas fault zone in central California was conducted in 1978. Results are complicated by the extreme lateral heterogeneity and low velocities in the fault zone. Other evidence for severe lateral velocity change across the fault zone lies in hypocenter bias and nodal plane distortion for earthquakes on the fault. Conventional interpretation and processing methods for reflection data are hard-pressed in this situation. Using the inverse ray method of May and Covey (1981), with an initial model derived from a variety of data and the impedance contrasts inferred from the preserved amplitude stacked section, an iterative inversion process yields a velocity model which, while clearly nonunique, is consistent with the various lines of evidence on the fault zone structure.

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