The shallow structure of a surface-rupturing fault in unconsolidated deposits from multi-scale electrical resistivity data: The 30 October 2016 Mw 6.5 central Italy earthquake case study

被引:21
作者
Villani, Fabio [1 ]
Sapia, Vincenzo [2 ]
机构
[1] Ist Nazl Geofis & Vulcanol, Laquila, Italy
[2] Ist Nazl Geofis & Vulcanol, Rome, Italy
关键词
Electrical resistivity tomography; Surface faulting; Fault imaging; Fault zone properties; Earthquake; Central Apennines; SEISMIC HAZARD ASSESSMENT; ACTIVE NORMAL-FAULT; SAN-ANDREAS FAULT; CENTRAL APENNINES; PERMEABILITY STRUCTURE; CONDUCTIVITY IMAGES; TECTONIC EVOLUTION; ABRUZZO APENNINES; OCCAMS INVERSION; DISPOSAL SITE;
D O I
10.1016/j.tecto.2017.08.001
中图分类号
P3 [地球物理学]; P59 [地球化学];
学科分类号
0708 ; 070902 ;
摘要
We report the results of a shallow electrical resistivity investigation performed across a normal fault that ruptured the surface displacing with average similar to 0.05 m vertical offset alluvial fan deposits (<23 kyr old) within an intermontane fault-bounded basin following the 30 October 2016 Mw 6.5 earthquake in central Italy. We adopted a multi-scale geophysical approach, by acquiring three 2-D electrical resistivity tomography (ERT) profiles centred on the coseismic ruptures, and characterized by different spatial resolution and investigation depth. Below the fault scarp, the ERT models show a narrow (similar to 10 m wide) and steeply-dipping moderately-resistive region (100-150 Omega m ), which we interpret as the electrical response of the fault zone displacing layers of relatively high-resistivity (300-700 Omega m ) values. We explain the electrical signature of the retrieved fault zone as due to an increment of permeability caused by coseismic fracturing, and to the subsequent water migration from adjacent shallow aquifers squeezed by compaction induced by seismic waves. By using a statistically-based classification of electrical units, we estimate that the shallowest alluvial fan layer is affected by 2.7 +/- 0.9 m vertical offset, which is consistent with the measured 2.3-2.8 m morphologic offset of the top fan surface, and suggesting a post-12 kyr throw-rate of 0.23 +/- 0.08 mm/yr. Similarly, we evaluate a post-23 kyr throw of 5.1 +/- 1.7 m, indicating a Late Pleistocene throw-rate of 0.22 +/- 0.07 mm/yr, in accordance with available paleoseismic data. We further hypothesize a minimal total fault throw >30 m, which likely accrued since the Middle Pleistocene (possibly in the last 350-500 kyr). The investigated fault structure is therefore an important splay characterized by a thick and highly permeable damage zone in unconsolidated deposits, and which ruptured the surface during several tens of strong (M > 6) earthquakes. (C) 2017 Elsevier B.V. All rights reserved.
引用
收藏
页码:628 / 644
页数:17
相关论文
共 123 条
[51]  
Ge. Mi. Na (Geomineraria Nazionale), 1963, BAC CAST NORC LIGN T, P207
[52]   Potential of Electrical Resistivity Tomography to Detect Fault Zones in Limestone and Argillaceous Formations in the Experimental Platform of Tournemire, France [J].
Gelis, C. ;
Revil, A. ;
Cushing, M. E. ;
Jougnot, D. ;
Lemeille, F. ;
Cabrera, J. ;
De Hoyos, A. ;
Rocher, M. .
PURE AND APPLIED GEOPHYSICS, 2010, 167 (11) :1405-1418
[53]   Depth and modes of Pliocene-Pleistocene crustal extension of the Apennines (Italy) [J].
Ghisetti, F ;
Vezzani, L .
TERRA NOVA, 1999, 11 (2-3) :67-72
[54]  
Giocoli A, 2015, NAT HAZARD EARTH SYS, V15, P315, DOI 10.5194/nhess-15-315-2015
[55]   Electrical Resistivity Tomography across the Paganica-San Demetrio fault system (L'Aquila 2009 earthquake) [J].
Giocoli, A. ;
Galli, P. ;
Giaccio, B. ;
Lapenna, V. ;
Messina, P. ;
Peronace, E. ;
Romano, G. ;
Piscitelli, S. .
BOLLETTINO DI GEOFISICA TEORICA ED APPLICATA, 2011, 52 (03) :457-469
[56]   CONSIDERATIONS ON THE SIGNIFICANCE OF SOME POSTGLACIAL FAULT SCARPS IN THE ABRUZZO APENNINES (CENTRAL ITALY) [J].
GIRAUDI, C .
QUATERNARY INTERNATIONAL, 1995, 25 :33-45
[57]  
Giraudi C., 2010, QUATERNARY RES, V75, P219
[58]   Middle and late Pleistocene glaciations in the Campo Felice Basin (central Apennines, Italy) [J].
Giraudi, Carlo ;
Bodrato, Giulia ;
Lucchi, Marianna Ricci ;
Cipriani, Nicola ;
Villa, Igor M. ;
Giaccio, Biagio ;
Zuppi, Giovanni M. .
QUATERNARY RESEARCH, 2011, 75 (01) :219-230
[59]  
Gruppo di Lavoro INGV sul terremoto di Amatrice, 2016, 1 GRUPP LAV INGV TER
[60]  
Gruppo di Lavoro INGV sul terremoto di Visso, 2016, RAPP SINT TERR VISS