Rapid response to the earthquake emergency of May 2012 in the Po Plain, northern Italy

Milena Moretti;  et al.

doi:10.4401/ag-6152

Rapid response to the earthquake emergency of May 2012 in the Po Plain, northern Italy

Annals of Geophysics ◽

10.4401/ag-6152 ◽

2012 ◽

Vol 55 (4) ◽

Author(s):

Milena Moretti ◽

et al.

Keyword(s):

Rapid Response ◽

Seismic Events ◽

Earthquake Physics ◽

Po Plain ◽

Seismic Sequences ◽

Rupture Length ◽

Earthquake Detection ◽

Tectonic Environment ◽

Seismic Networks ◽

High Degree

Rapid-response seismic networks are an important element in the response to seismic crises. They temporarily improve the detection performance of permanent monitoring systems during seismic sequences. The improvement in earthquake detection and location capabilities can be important for decision makers to assess the current situation, and can provide invaluable data for scientific studies related to hazard, tectonics and earthquake physics. Aftershocks and the clustering of the locations of seismic events help to characterize the dimensions of the causative fault. Knowing the number, size and timing of the aftershocks or the clustering seismic events can help in the foreseeing of the characteristics of future seismic sequences in the same tectonic environment. Instrumental rapid response requires a high degree of preparedness. A mission in response to a magnitude (Ml) 6 event with a rupture length of a few tens of kilometers might involve the deployment within hours to days of 30-50 seismic stations in the middle of a disaster area of some hundreds of square kilometers, and the installation of an operational center to help in the logistics and communications. When an earthquake strikes in a populated area, which is almost always the case in Italy, driving the relevant seismic response is more difficult. […]

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Ground motion prediction from nearest seismogenic zones in and around Greater Cairo Area, Egypt

Natural Hazards and Earth System Science ◽

10.5194/nhess-10-1495-2010 ◽

2010 ◽

Vol 10 (7) ◽

pp. 1495-1511 ◽

Cited By ~ 32

Author(s):

Keyword(s):

Ambient Noise ◽

Ground Motions ◽

Empirical Relationship ◽

Seismic Events ◽

Ground Motion Prediction ◽

Source Characterization ◽

Source Characteristics ◽

Rupture Length ◽

Greater Cairo

Abstract. This paper reviews the likely source characteristics, focal source mechanism and fault patterns of the nearest effective seismogenic zones to Greater Cairo Area. Furthermore, Mmax and ground accelerations related to the effective seismic events expected in future from those seismogenic zones are well evaluated. For this purpose, the digital waveform of earthquakes than ML=3 that occurred in and around Greater Cairo Area from 1997 to 2008 which have been recorded by the Egyptian National Seismological Network, are used to study source characterization, focal mechanism and fault pattern of the seismogenic zones around Greater Cairo Area. The ground motions are predicted from seismogenic zones to assess seismic hazard in the northeastern part of Greater Cairo, where three effective seismogenic zones, namely Abou Zabul, southeast Cairo trend and Dahshour area, have the largest effect to the Greater Cairo Area. The Mmax was determined, based upon an empirical relationship between the seismic moment and the rupture length of the fault during the earthquake. The estimated Mmax expected from Abou Zabul, southeast Cairo trend, Dahshour seismic sources are of Mw magnitudes equal to 5.4, 5.1, and 6.5, respectively. The predominant fundamental frequency and soil amplification characteristics at the area were obtained using boreholes data and in-situ ambient noise measurement.

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Lithospheric structure models applied for locating the Romanian seismic events

Annals of Geophysics ◽

10.4401/ag-4215 ◽

1994 ◽

Vol 37 (3) ◽

Author(s):

M. Rizescu ◽

E. Popescu ◽

V. Oancea ◽

D. Enescu

Keyword(s):

Constant Velocity ◽

Seismic Waves ◽

Seismic Events ◽

Lithospheric Structure ◽

Structural Units ◽

Data Set ◽

Velocity Models ◽

Seismic Sequences ◽

Geological Information ◽

Propagation Velocities

The paper presents our attempts made for improving the locations obtained for local seismic events, using refined lithospheric structure models. The location program (based on Geiger method) supposes a known model. The program is run for some seismic sequences which occurred in different regions, on the Romanian territory, using for each of the sequences three velocity models: 1) 7 layers of constant velocity of seismic waves, as an average structure of the lithosphere for the whole territory; 2) site dependent structure (below each station), based on geophysical and geological information on the crust; 3) curves deseribing the dependence of propagation velocities with depth in the lithosphere, characterizing the 7 structural units delineated on the Romanian territory. The results obtained using the different velocity models are compared. Station corrections are computed for each data set. Finally, the locations determined for some quarry blasts are compared with the real ones.

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Impact of hurricanes Irma and Maria on the Pacific Tsunami Warning Center initial tsunami warning capability for the Caribbean region

Natural Hazards and Earth System Science ◽

10.5194/nhess-19-1865-2019 ◽

2019 ◽

Vol 19 (8) ◽

pp. 1865-1880

Author(s):

Victor Sardina ◽

David Walsh ◽

Kanoa Koyanagi ◽

Stuart Weinstein ◽

Nathan Becker ◽

...

Keyword(s):

Response Times ◽

Virgin Islands ◽

Tsunami Warning ◽

Caribbean Region ◽

Temporary Reduction ◽

Earthquake Detection ◽

The Pacific ◽

The Caribbean ◽

Seismic Networks ◽

The Impact

Abstract. In September 2017, hurricanes Irma and Maria wreaked havoc across the Caribbean region. While obliterating the infrastructure in the Caribbean nations found along their path, both hurricanes gradually destroyed the existing seismic networks. We quantified the impact of the hurricanes on the Pacific Tsunami Warning Center (PTWC) initial tsunami warning capability for the Caribbean region relying on the computation of theoretical earthquake detection and response times after accounting for hurricane-related station outages. The results show that the hurricanes rendered 38 % of the 146 stations available in the Caribbean inoperative. Within the eastern Caribbean region monitored by PTWC the hurricanes exacerbated outages to an astonishing 82 % of the available 76 seismic stations. Puerto Rico, the Virgin Islands, and the Lesser Antilles suffered the brunt of both hurricanes, and their seismic networks nearly disappeared. The double punch delivered by two successive category 5 hurricanes added up to 02:43 and 04:33 min to the earthquake detection and response times, effectively knocking out PTWC's local tsunami warning capabilities in the region. Emergency adjustments, including the temporary reduction of the number of stations required for earthquake detection and ML magnitude release, enabled a faster response to earthquakes in the region than otherwise possible in the aftermath of hurricanes Irma and Maria.

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Effect of Combining Catalogs with Different Completeness

10.5194/egusphere-egu2020-1749 ◽

2020 ◽

Author(s):

Myunghyun Noh

Keyword(s):

Korean Peninsula ◽

North Korea ◽

Seismic Network ◽

The Other ◽

Earthquake Catalog ◽

Detection Capability ◽

Chi Square ◽

Earthquake Detection ◽

Seismic Networks ◽

Target Monitoring

In most seismic studies, we prefer the earthquake catalog that covers a larger region and/or a longer period. We usually combine two or more catalogs to achieve this goal. When combining catalogs, however, care must be taken because their completeness is not identical so that unexpected flaws may be caused.We tested the effect of combining inhomogeneous catalogs using the catalog of Korea Meteorological Administration (KMA). In fact, KMA provides a single catalog containing the earthquakes occurred in and around the whole Korean Peninsula. Like the other seismic networks, however, the configuration of the KMA seismic network is not uniform over its target monitoring region, so is the earthquake detection capability. The network is denser in the land than in the off-shore. Moreover, there are no seismic information available from North Korea. Based on these, we divided the KMA catalog into three sub-catalogs; SL, NL, and AO catalogs. The SL catalog contains the earthquakes occurred in the land of South Korea while the NL catalog contains those in the land of North Korea. The AO catalog contains all earthquakes occurred in the off-shore surrounding the peninsula.The completeness of a catalog is expressed in terms of mc, the minimum magnitude above which no earthquakes are missing. We used the Chi-square algorithm by Noh (2017) to estimate the mc. It turned out, as expected, that the mc of the SL is the smallest among the three. Those of NL and AO are comparable. The mc of the catalog combining the SL and AO is larger than those of individual catalogs before combining. The mc is largest when combining all the three. If one needs more complete catalog, he or she had better divide the catalog into smaller ones based on the spatiotemporal detectability of the seismic network. Or, one may combine several catalogs to cover a larger region or a longer period at the expense of catalog completeness.

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Analysis of the seismic response to reservoir development and long-term operation at the Rittershoffen deep geothermal site

10.5194/egusphere-egu2020-20317 ◽

2020 ◽

Author(s):

Rike Köpke ◽

Olivier Lengliné ◽

Jean Schmittbuhl ◽

Emmanuel Gaucher ◽

Thomas Kohl

Keyword(s):

Fluid Flow ◽

Seismic Response ◽

Template Matching ◽

Fracture Network ◽

Seismic Events ◽

Valuable Insight ◽

Hydraulic Stimulation ◽

Reservoir Development ◽

Seismic Networks ◽

Insight Into

In a geothermal reservoir, seismicity may be induced due to changes in the subsurface as a result of drilling, stimulation or circulation operations. The induced seismic events are therefore strongly linked to the fluid flow, the mechanical state of the reservoir and the geological structures that impact the stress field and make this fluid flow possible. Here, the study is based on the monitoring of the development and operation of the deep geothermal site at Rittershoffen (Alsace, France) using different seismic networks covering various operational periods from September 2012 to present, including the drilling of the well doublet GRT1/GRT2, stimulation of GRT1 and well testing. The seismicity induced by these operations has the potential to give valuable insight into the geomechanical behaviour of the reservoir and the geometry of the fracture network. The present study gives an overview of the spatial and temporal development of the induced seismicity and the magnitudes of the events to provide insights into active structures in the reservoir.&#160;To improve the level of detection, we first apply a template matching algorithm to the continuous waveforms recorded by the seismic networks. After running the detection with the template matching, the relative locations of all detected events are calculated as well as relative magnitudes. This workflow is applied to the whole time period from the start of the drilling in 2012 up to 2017. The spatial and temporal evolution of the events and their magnitudes shows how the different operations during reservoir development influence the seismogenic development of the reservoir and the seismic activity during continuous operation of the site. Further analysis like b-value computation, estimation of the best-fitting planes to the seismic clouds and evaluation of the waveform correlation between the seismic events give insight into the processes that induced the seismicity and the relation between different seismic intervals.&#160;Focus of the present study is on the similarities and differences in the seismic response of the reservoir to the three subsequent stimulations of GRT1, called thermal, chemical and hydraulic stimulation. Results show that the seismicity induced during the hydraulic stimulation is much stronger in terms of seismicity rate and magnitudes than seismicity induced during thermal stimulation and migrates further into the reservoir. Noticeably, after a seismically quiet period of four days after the hydraulic stimulation a short burst of seismicity occurred unrelated to any operations on site. Seismicity during this delayed interval proved to have quite distinct characteristics from the seismicity induced during injection. While no significant seismicity was induced during chemical stimulation, the operation may have had an important influence on the seismic response of the reservoir during hydraulic stimulation by changing the state of the present fracture network.

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Waveform cross-correlation-based earthquake detection applied to microseismicity near the central Alpine Fault, New Zealand

10.5194/egusphere-egu2020-5099 ◽

2020 ◽

Author(s):

Konstantinos Michailos ◽

Calum J. Chamberlain ◽

John Townend

Keyword(s):

New Zealand ◽

Plate Boundary ◽

Earthquake Activity ◽

Earthquake Catalog ◽

Definitive Evidence ◽

Repeating Earthquakes ◽

Earthquake Detection ◽

Alpine Fault ◽

Waveform Cross Correlation ◽

Seismic Networks

The Alpine Fault is a major plate boundary oblique strike-slip fault, known to fail in large M 7-8 earthquakes, posing a significant seismic hazard to southern and central New Zealand. The central part of the Alpine Fault exhibits low seismic activity when compared to adjacent areas. We have examined the smaller-magnitude earthquake activity occurring along the central portion of the Alpine Fault using data from five temporary seismic networks from late 2008 to early 2017.We have created the most complete and accurate earthquake catalog at the central Alpine Fault to date (9,111 earthquake locations with magnitudes ranging from ML -1.2 to 4.6). We used this catalog as templates with a matched-filtering earthquake detection method and further extend the earthquake catalog. This even more comprehensive earthquake catalog will provide more definitive evidence for the seismicity characteristics observed and better insights into the fault zone&#8217;s geometry.&#160;Taking advantage of this extensive earthquake catalog, we also aim to examine whether there are any repeating highly similar seismic signals (repeating earthquakes). These repeating earthquakes can potentially help better determine the locked and creeping sections of the Alpine Fault and possibly quantify the total amount of creep taking place with respect to seismic deformation.

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The Campotosto linkage fault zone between the 2009 and 2016 seismic sequences of central Italy: Implications for seismic hazard analysis

Geological Society of America Bulletin ◽

10.1130/b35788.1 ◽

2020 ◽

Author(s):

Emanuele Tondi ◽

Danica Jablonská ◽

Tiziano Volatili ◽

Maddalena Michele ◽

Stefano Mazzoli ◽

...

Keyword(s):

Seismic Hazard ◽

Fault Zone ◽

Central Italy ◽

Seismic Events ◽

Seismic Gap ◽

Seismic Zone ◽

Seismic Sequence ◽

Geological Evidence ◽

Seismic Sequences ◽

Seismogenic Faults

In the last decade central Italy was struck by devastating seismic sequences resulting in hundreds of casualties (i.e., 2009-L′Aquila moment magnitude [Mw] = 6.3, and 2016-Amatrice-Visso-Norcia Mw max = 6.5). These seismic events were caused by two NW-SE−striking, SW-dipping, seismogenic normal faults that were modeled based on the available focal mechanisms and the seismic moment computed during the relative mainshocks. The seismogenic faults responsible for the 2009-L′Aquila Mw = 6.3 (Paganica Fault—PF) and 2016-Amatrice-Visso-Norcia Mw max = 6.5 (Monte Vettore Fault—MVF) are right-stepping with a negative overlap (i.e., underlap) located at the surface in the Campotosto area. This latter was affected by seismic swarms with magnitude ranging from 5.0 to 5.5 during the 2009 seismic sequence and then in 2017 (i.e., a few months later than the mainshocks related with the 2016 seismic sequence). In this paper, the seismogenic faults related to the main seismic events that occurred in the Campotosto Seismic Zone (CSZ) were modeled and interpreted as a linkage fault zone between the PF and MVF interacting seismogenic faults. Based on the underlap dimension, the seismogenic potential of the CSZ is in the order of Mw = 6.0, even in the case that all the faults belonging to the zone were activated simultaneously. This has important implications for seismic hazard assessment in an area dominated by the occurrence of a major NW-SE−striking extensional structure, i.e., the Monte Gorzano Fault (MGF). Mainly due to its geomorphologic expression, this fault has been considered as an active and silent structure (therefore representing a seismic gap) able to generate an earthquake of Mw max = 6.5−7.0. However, the geological evidence provided with this study suggests that the MGF is of early (i.e., pre- to syn-thrusting) origin. Therefore, the evaluation of the seismic hazard in the Campotosto area should not be based on the geometrical characteristics of the outcropping MGF. This also generates substantial issues with earthquake geological studies carried out prior to the recent seismic events in central Italy. More in general, the 4-D high-resolution image of a crustal volume hosting an active linkage zone between two large seismogenic structures provides new insights into the behavior of interacting faults in the incipient stages of connection.

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The Finnish National Seismic Network: Toward Fully Automated Analysis of Low-Magnitude Seismic Events

Seismological Research Letters ◽

10.1785/0220200352 ◽

2021 ◽

Author(s):

Toni Veikkolainen ◽

Jari Kortström ◽

Tommi Vuorinen ◽

Ilmo Salmenperä ◽

Tuija Luhta ◽

...

Keyword(s):

Background Activity ◽

Automated Analysis ◽

Seismic Events ◽

Crystalline Bedrock ◽

Management Concepts ◽

Challenges And Opportunities ◽

Anthropogenic Seismicity ◽

Seismic Networks ◽

High Level ◽

Seismic Background

Abstract We present an overview of the seismic networks, products, and services in Finland, northern Europe, and the challenges and opportunities associated with the unique combination of prevailing crystalline bedrock, low natural intraplate seismic background activity, and a high level of anthropogenic seismicity. We introduce national and local seismic networks, explain the databases, analysis tools, and data management concepts, outline the Finnish macroseismic service, and showcase data from the 2017 M 3.3 Liminka earthquake in Ostrobothnia, Finland.

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Unification of data from various seismic catalogues to study seismic activity in the Carpathians Mountain arc

Open Geosciences ◽

10.1515/geo-2019-0065 ◽

2019 ◽

Vol 11 (1) ◽

pp. 837-842

Author(s):

Agnieszka Braclawska ◽

Adam Filip Idziak

Keyword(s):

Central Europe ◽

Seismic Data ◽

Seismic Activity ◽

Earthquake Catalogue ◽

Active Area ◽

Seismic Events ◽

Large Area ◽

Carpathian Mountains ◽

The Carpathians ◽

Seismic Networks

Abstract The Carpathian Mountainsarc is the most seismically active area in Central Europe. Analysis of the seismicity of entire Carpathian arc requires data from each of the particular catalogues which have to be properly and uniformly entered, standardized and merged. For our study we first had to prepare a database of seismic events (ML ≥ 1.6) compiled from the data of earthquakes taken from individual national seismic networks as well as data from international seismic centers. However, a careful review of these catalogues has uncovered significant inconsistencies, particularly discrepancies in the description of the location, magnitude and completeness of seismic events. To address these inconsistencies, a newly created compound earthquake catalogue was compiled from the aforementioned seismic catalogues and included events that occurred in the Carpathian Mountains arc area between 1976 and 2017. This work is intended to point out some of the problems associated with collecting data from various seismic catalogues as well as the need for their very careful verification, in order to create a uniform set of seismic data across a large area spanning numerous countries. The results suggest that compiling a uniform and dependable earthquake catalogue is crucial for reliable seismic studies.

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