scholarly journals Surface-Rupturing Historical Earthquakes in Australia and Their Environmental Effects: New Insights from Re-Analyses of Observational Data

Geosciences ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 408 ◽  
Author(s):  
King ◽  
Quigley ◽  
Clark

We digitize surface rupture maps and compile observational data from 67 publications on ten of eleven historical, surface-rupturing earthquakes in Australia in order to analyze the prevailing characteristics of surface ruptures and other environmental effects in this crystalline basement-dominated intraplate environment. The studied earthquakes occurred between 1968 and 2018, and range in moment magnitude (Mw) from 4.7 to 6.6. All earthquakes involved co-seismic reverse faulting (with varying amounts of strike-slip) on single or multiple (1–6) discrete faults of ≥ 1 km length that are distinguished by orientation and kinematic criteria. Nine of ten earthquakes have surface-rupturing fault orientations that align with prevailing linear anomalies in geophysical (gravity and magnetic) data and bedrock structure (foliations and/or quartz veins and/or intrusive boundaries and/or pre-existing faults), indicating strong control of inherited crustal structure on contemporary faulting. Rupture kinematics are consistent with horizontal shortening driven by regional trajectories of horizontal compressive stress. The lack of precision in seismological data prohibits the assessment of whether surface ruptures project to hypocentral locations via contiguous, planar principal slip zones or whether rupture segmentation occurs between seismogenic depths and the surface. Rupture centroids of 1–4 km in depth indicate predominantly shallow seismic moment release. No studied earthquakes have unambiguous geological evidence for preceding surface-rupturing earthquakes on the same faults and five earthquakes contain evidence of absence of preceding ruptures since the late Pleistocene, collectively highlighting the challenge of using mapped active faults to predict future seismic hazards. Estimated maximum fault slip rates are 0.2–9.1 m Myr-1 with at least one order of uncertainty. New estimates for rupture length, fault dip, and coseismic net slip can be used to improve future iterations of earthquake magnitude—source size—displacement scaling equations. Observed environmental effects include primary surface rupture, secondary fracture/cracks, fissures, rock falls, ground-water anomalies, vegetation damage, sand-blows / liquefaction, displaced rock fragments, and holes from collapsible soil failure, at maximum estimated epicentral distances ranging from 0 to ~250 km. ESI-07 intensity-scale estimates range by ± 3 classes in each earthquake, depending on the effect considered. Comparing Mw-ESI relationships across geologically diverse environments is a fruitful avenue for future research.

2020 ◽  
Vol 110 (4) ◽  
pp. 1427-1456 ◽  
Author(s):  
Jessica Ann Thompson Jobe ◽  
Belle Philibosian ◽  
Colin Chupik ◽  
Timothy Dawson ◽  
Scott E. K. Bennett ◽  
...  

ABSTRACT The July 2019 Ridgecrest earthquakes in southeastern California were characterized as surprising by some, because only ∼35% of the rupture occurred on previously mapped faults. Employing more detailed inspection of pre-event high-resolution topography and imagery in combination with field observations, we document evidence of active faulting in the landscape along the entire fault system. Scarps, deflected drainages, and lineaments and contrasts in topography, vegetation, and ground color demonstrate previous slip on a dense network of orthogonal faults, consistent with patterns of ground surface rupture observed in 2019. Not all of these newly mapped fault strands ruptured in 2019. Outcrop-scale field observations additionally reveal tufa lineaments and sheared Quaternary deposits. Neotectonic features are commonly short (<2  km), discontinuous, and display en echelon patterns along both the M 6.4 and M 7.1 ruptures. These features are generally more prominent and better preserved outside the late Pleistocene lake basins. Fault expression may also be related to deformation style: scarps and topographic lineaments are more prevalent in areas where substantial vertical motion occurred in 2019. Where strike-slip displacement dominated in 2019, the faults are mainly expressed by less prominent tonal and vegetation features. Both the northeast- and northwest-trending active-fault systems are subparallel to regional bedrock fabrics that were established as early as ∼150  Ma, and may be reactivating these older structures. Overall, we estimate that 50%–70% (i.e., an additional 15%–35%) of the 2019 surface ruptures could have been recognized as active faults with detailed inspection of pre-earthquake data. Similar detailed mapping of potential neotectonic features could help improve seismic hazard analyses in other regions of eastern California and elsewhere that likely have distributed faulting or incompletely mapped faults. In areas where faults cannot be resolved as single throughgoing structures, we recommend a zone of potential faulting should be used as a hazard model input.


2021 ◽  
Author(s):  
Matija Vukovski ◽  
Marko Budić ◽  
Marko Špelić ◽  
Josip Barbača ◽  
Nikola Belić ◽  
...  

<p>On December 29th, 2020, a strong Mw 6.4 earthquake hit central Croatia. The epicenter was located approximately 3 km southwest of Petrinja, and the intensity was estimated to VIII-IX EMS. The earthquake led to significant environmental effects related to earthquake magnitude, focal depth, and geological and geotechnical properties of the affected area.<br>The Croatian Geological Survey (HGI-CGS) conducted extensive geological and geodetic surveys starting a few hours following the main shock to measure the earthquake’s effects,<br>including those on infrastructures. Ten geologists from the Department of Geology carried out surveys from Decmber 31st, 2020 to January 7th, 2021 along the potential seismogenic source (inferred from geological maps and InSAR data) and in the wider epicentral area that suffered significant damage (e.g., Glina and Sisak).<br>During a second phase, researchers from the University of Zagreb (PMF UniZG), Slovenia (GeoZS), Italy (INGV, ISPRA, U. Chieti) and France (CEREGE, IRSN) were mobilized to complete the observations. The collaboration with these geologists allowed to deepen the investigations and to bring further detail to quantify the effects. The surveys were then compiled based on data formats used by the European Community, namely those of the INGV EMERGEO team (Villani et al., 2017; for environmental effects including surface ruptures and liquefaction) and those of the SURE group (Baize et al., 2019 for surface ruptures).<br>These observations revealed that the earthquake triggered a discontinuous, few km-long surface rupture with a maximum displacement of about 20 cm, which is consistent with the lower average of observations made on similar events (Wells and Coppersmith, 1994). Liquefaction spread over several tens of square kilometers mostly in river plains, the most distant being about 20 km from the epicenter (to be confirmed!). Other observed effects include lateral spreading, landslides, groundwater regime changes, rockfalls, and various infrastructure damage.<br>The compilation of the acquired dataset into a unified database, consistent with database of other historical and recent events, is essential for establishing reliable empirical relations between geological effects and physical characteristics of earthquakes (magnitude, depth). This forms the basis for seismic hazard assessments, whether for “surface rupture”, “liquefaction”, or “ground-shaking” potential.</p>


Solid Earth ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 2211-2234
Author(s):  
Christoph Grützner ◽  
Simone Aschenbrenner ◽  
Petra Jamšek Rupnik ◽  
Klaus Reicherter ◽  
Nour Saifelislam ◽  
...  

Abstract. The Dinaric Fault System in western Slovenia, consisting of NW–SE-trending, right-lateral strike-slip faults, accommodates the northward motion of Adria with respect to Eurasia. These active faults show a clear imprint in the morphology, and some of them hosted moderate instrumental earthquakes. However, it is largely unknown if the faults also had strong earthquakes in the late Quaternary. This hampers our understanding of the regional tectonics and the seismic hazard. Geological evidence of co-seismic surface ruptures only exists for one historical event, the 1511 Idrija earthquake with a magnitude of ∼ M 6.8, but the causative fault is still disputed. Here we use geomorphological data, near-surface geophysical surveys, and paleoseismological trenching to study two of these faults: the Predjama Fault and the Idrija Fault. In a paleoseismological trench across the Predjama Fault we found deformation features that may have been caused by an earthquake between 13–0.7 ka, very likely not earlier than 8.4 ka. At the Idrija Fault, a surface-rupturing earthquake happened around 2.5 ka. We show that instrumental and historical seismicity data do not capture the strongest events in this area.


Author(s):  
Machiel Lamers ◽  
Jeroen Nawijn ◽  
Eke Eijgelaar

Over the last decades a substantial and growing societal and academic interest has emerged for the development of sustainable tourism. Scholars have highlighted the contribution of tourism to global environmental change and to local, detrimental social and environmental effects as well as to ways in which tourism contributes to nature conservation. Nevertheless the role of tourist consumers in driving sustainable tourism has remained unconvincing and inconsistent. This chapter reviews the constraints and opportunities of political consumerism for sustainable tourism. The discussion covers stronger pockets and a key weak pocket of political consumerism for sustainable tourism and also highlights inconsistencies in sustainable tourism consumption by drawing on a range of social theory arguments and possible solutions. The chapter concludes with an agenda for future research on this topic.


Author(s):  
R. Van Dissen ◽  
J. Begg ◽  
Y. Awata

Approximately one year after the Great Hanshin (Kobe) Earthquake, two New Zealand geologists were invited to help with the Geological Survey of Japan's paleoearthquake/active fault studies in the Kobe/Awaji area. Trenches excavated across the Nojima fault, which ruptured during the Great Hanshin Earthquake, showed evidence of past surface rupture earthquakes, with the age of the penultimate earthquake estimated at approximately 2000 years. A trench across the Higashiura fault, located 3-4 km southeast of the Nojima fault, revealed at least two past surface rupture earthquakes. The timing of the older earthquakes is not yet known, but pottery fragments found in the trench constrain the timing of the most recent earthquake at less than 500-600 years. Historical records for this part of Japan suggest that within the last 700 years there has been only one regionally felt earthquake prior to the 1995 Great Hanshin Earthquake, and this was the AD 1596 Keicho Earthquake. It thus seems reasonable to suggest that the Higashiura fault was, at least in part, the source of the AD 1596 Keicho Earthquake.


2020 ◽  
Vol 14 (1) ◽  
pp. 298-308
Author(s):  
Bhatawdekar Ramesh Murlidhar ◽  
Danial Jahed Armaghani ◽  
Edy Tonnizam Mohamad

Background: Blasting is commonly used for loosening hard rock during excavation for generating the desired rock fragmentation required for optimizing the productivity of downstream operations. The environmental impacts resulting from such blasting operations include the generation of flyrock, ground vibrations, air over pressure (AOp) and rock fragmentation. Objective: The purpose of this research is to evaluate the suitability of different computational techniques for the prediction of these environmental effects and to determine the key factors which contribute to each of these effects. This paper also identifies future research needs for the prediction of the environmental effects of blasting operations in hard rock. Methods: The various computational techniques utilized by the researchers in predicting blasting environmental issues such as artificial neural network (ANN), fuzzy interface system (FIS), imperialist competitive algorithm (ICA), and particle swarm optimization (PSO), were reviewed. Results: The results indicated that ANN, FIS and ANN-ICA were the best models for prediction of flyrock distance. FIS model was the best technique for the prediction of AOp and ground vibration. On the other hand, ANN was found to be the best for the assessment of fragmentation. Conclusion and Recommendation: It can be concluded that FIS, ANN-PSO, ANN-ICA models perform better than ANN models for the prediction of environmental issues of blasting using the same database. This paper further discusses how some of these techniques can be implemented by mining engineers and blasting team members at operating mines for predicting blast performance.


2021 ◽  
Author(s):  
Selina S. Fenske ◽  
Virginia G. Toy ◽  
Bernhard Schuck ◽  
Anja M. Schleicher ◽  
Klaus Reicherter

<p>The tectonophysical paradigm that earthquake ruptures should not start, or easily propagate into, the shallowest few kilometers of Earth’s crust makes it difficult to understand why damaging surface displacements have occurred during historic events. The paradigm is supported by decades of analyses demonstrating that near the surface, most major fault zones are composed of clay minerals – particularly extraordinarily weak smectites – which most laboratory physical measurements suggest should prevent surface rupture if present. Recent studies of New Zealand’s Alpine Fault Zone (AFZ) demonstrate smectites are absent from some near surface fault outcrops, which may explain why this fault was able to offset the surface locally in past events. The absence of smectites in places within the AFZ can be attributed to locally exceptionally high geothermal gradients related to circulation of meteoric (surface-derived) water into the fault zone, driven by significant topographic gradients. The record of surface rupture of the AFZ is heterogeneous, and no one has yet systematically examined the distribution of segments devoid of evidence for recent displacement. There are significant implications for seismic hazard, which comprises both surface displacements and ground shaking with intensity related to the area of fault plane that ruptures (which will be reduced if ruptures do not reach the surface).  We will present results of new rigorous XRD clay mineral analyses of AFZ principal slip zone gouges that indicate where smectites are present, and consider if these display systematic relationships to surface displacement records. We also plan to apply the same methodology to the Carboneras Fault Zone in Spain, and the infrequent Holocene-active faults in Western Germany.</p>


1988 ◽  
Vol 78 (2) ◽  
pp. 956-978
Author(s):  
William B. Bull ◽  
Philip A. Pearthree

Abstract Movements along the Pitaycachi fault since the Miocene juxtaposed different alluvial units and created 2- to 45-m-high fault scarps downslope from a pedimented mountain front prior to 1887. In 1887, a major earthquake formed a 75-km-long, 12- to 4-m-high scarp along the trace of prehistoric surface ruptures. Diverse evidence from many study sites indicates that about 200,000 yr elapsed between the prior (youngest Pleistocene) event and the 1887 surface rupture. Cumulative displacements of Pliocene(?) to mid-Pleistocene alluvial fans and stream terraces decrease with decreasing age. The trace of the prior rupture was largely buried by sheets of late Pleistocene and Holocene piedmont alluvium. Late Pleistocene soils are offset about the same amount as the height of the 1887 scarp. Valleys that are as much as 40 m deep and 0.5 to 0.9 km wide have been eroded since the prior event; they contain multiple late Pleistocene and Holocene stream terraces that were not faulted until 1887. Pre-1887 alluvial fault scarps were degraded to 2° to 9° slopes before the 1887 event, even in resistant materials such as clay-rich soil horizons with unweathered rhyolite cobbles and calcrete. Scarp height-maximum slope regressions and diffusion-equation analyses for reconstructed pre-1887 scarp profiles indicate that the prior event occurred more than 100,000 yr ago. Acceleration of scarp degradation rates during the Holocene, and/or relatively resistant materials exposed in the scarps, would increase the age estimates to 200,000 yr or more. Very long recurrence intervals are the characteristic style of movement on the Pitaycachi fault. At one site, six ages of diverse valley fills were inset into pedimented granodiorite upslope from the fault between the prior and 1887 events. Only 3 m of relief remained before the 1887 rupture increased the scarp height from 3 to 6 m. Some hillslopes have triangular talus facets of carbonatecemented colluvium that resulted from infrequent fault movements and intervening periods of erosion. Smooth hillsides of resistant volcanic rocks between the facets show that virtually all of the prior surface-rupture event scarps had been removed by prolonged slope degradation.


2018 ◽  
Vol 34 (4) ◽  
pp. 1585-1610 ◽  
Author(s):  
Stefano Gori ◽  
Emanuela Falcucci ◽  
Fabrizio Galadini ◽  
Paolo Zimmaro ◽  
Alberto Pizzi ◽  
...  

The three mainshock events (M6.1 24 August, M5.9 26 October, and M6.5 30 October 2016) in the Central Italy earthquake sequence produced surface ruptures on known segments of the Mt. Vettore–Mt. Bove normal fault system. As a result, teams from Italian national research institutions and universities, working collaboratively with the U.S. Geotechnical Extreme Events Reconnaissance Association (GEER), were mobilized to collect perishable data. Our reconnaissance approach included field mapping and advanced imaging techniques, both directed towards documenting the location and extent of surface rupture on the main fault exposure and secondary features. Mapping activity occurred after each mainshock (with different levels of detail at different times), which provides data on the progression of locations and amounts of slip between events. Along the full length of the Mt. Vettore–Mt. Bove fault system, vertical offsets ranged from 0–35 cm and 70–200 cm for the 24 August and 30 October events, respectively. Comparisons between observed surface rupture displacements and available empirical models show that the three events fit within expected ranges.


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