Historical Earthquake Catalogs Research Articles

Structure and Deformation History of the Rapidly Growing Tainan Anticline at the Deformation Front of the Taiwan Mountain Belt

AbstractThis study aims at further documenting the mechanisms of shortening at the front of fold‐and‐thrust belts. We focus on an actively growing anticline located at the deformation front of the Taiwan fold‐and‐thrust belt. Based on a multidisciplinary approach combining mainly subsurface data and geodetic techniques, we show that the Tainan anticline is a pure‐shear fault‐bend fold growing above a 38–45° west dipping back thrust, the Houchiali fault, rooted on a 3.8‐km‐deep detachment. The cumulative shortening is estimated at 2–3 km since 310 ± 50 ka, including ~30–50% of horizontal compaction shortening. The significance of the fold is little in terms of total shortening at the scale of the mountain piedmont, yet the Holocene shortening rate of 10.3 ± 1.0 mm/a accounts for 25% of the present‐day shortening rate across the piedmont. Earthquake scaling relationships applied to the Houchiali fault predict Mw~6 earthquakes that would occur a lot more frequently than indicated from historical earthquake catalogs. Hence, the aseismic slip behavior observed from geodetic measurements since two decades is a representative behavior of the fault at least at the scale of a few centuries. Our results bear out the dominance of pure‐shear folding at the front of fold‐and‐thrust belts and support horizontal compaction as a significant shortening mechanism. In contrast, the back thrust wedge structure and the aseismic slip are peculiar characteristics that likely arise from the combination of low friction and high‐pore pressure related to the thick mudstone formation hosting the wedge and of high syntectonic sedimentation rates.

The Stratigraphy of Compound Sand Blows at Sites of Recurrent Liquefaction: Implications for Paleoseismicity Studies

Paleoliquefaction studies provide valuable information for seismic hazard analyses in areas where the return period of moderate to large events is longer than the duration of the historical earthquake catalog (e.g., Central-Eastern and Pacific Northwest United States). Toward this end, paleoliquefaction studies require accurate and detailed assessments of individual features and of the extent of the paleoliquefaction field for the event, with the difficulty of accurately interpreting field observations increasing in areas where recurrent liquefaction was triggered by spatiotemporally clustered paleo events. Accordingly, undisturbed features formed by recurrent liquefaction during the 2010–2011 Canterbury, New Zealand, earthquake sequence were studied to facilitate interpretation of paleoliquefaction analogs. Silt drapes demarcated multiple episodes of liquefaction in the sand blows, with the thickness of the silt drapes correlating to the fines content of the liquefied source stratum. However, no ubiquitous trends in the spatial sorting of grain sizes in the coarser fraction of the ejecta underlying silt drapes were observed. This study provides a modern analog to recurrent paleoliquefaction evidence and has important implications for interpretation of seismic hazards.

On the Nature of Seismic Phenomena in Platform Areas: A Case Study of Belarus

When compiling historical earthquake catalogs, the main problem is to validate the reliability of information to exclude false reports. Detailed descriptions from reliable sources contribute to more precise intensity assessment. Additionally, in low-active territories, very important problem of identifying the nature of the event has to be solved. Earthquakes generated by tectonic or other activity (such as landslides or karst collapses) may have similar descriptions. Recently, cryoseisms have also been considered a possible source of the ground surface shaking. Seismic events in Belarus reported based on noninstrumental data and having fundamentally different interpretations in different publications are studied. The analysis is based on original information from primary sources. It is shown that two out of four seismic events are cryoseisms, while the other two are not related to the territory of Belorussia.

Fault Slip Rates and Seismic Moment Deficits on Major Faults in Ordos Constrained by GPS Observation

The Ordos Block, surrounded by numerous active faults, is a relatively rigid but dangerous area with many strong historical earthquakes. We derive the block rotation velocity and fault slip rates in this area by using GPS data recorded from 1999 to 2007 and implementing an elastic block model. Instead of assuming vertical faults, as did most previous studies in and around Ordos, we use an improved method to invert for the fault dip angles and construct a closed 3-D fault system in our inversion. The predicted slip rates range from <1 mm/yr to ~ 10 mm/yr. Our results are roughly consistent with geological and other geodetic observations. Using the estimated slip rates, we also calculate the cumulative seismic moment due to fault locking and the released moment from historical earthquake catalogues. A comparison of the two quantities indicates that the Hetao Rift has an unreleased seismic moment equal to a Mw 7.9 earthquake, which is also indicated by frequent earthquakes above M6 after 1900.

An Mw‐Based Historical Earthquake Catalog for Mainland China

Research Article| September 25, 2017 An Mw‐Based Historical Earthquake Catalog for Mainland China Jia Cheng; Jia Cheng aKey Laboratory of Active Tectonics & Volcano, Institute of Geology, China Earthquake Administration, Beijing 100029, China, chengjiajc@gmail.com Search for other works by this author on: GSW Google Scholar Yufang Rong; Yufang Rong bResearch Division, FM Global, 1151 Boston‐Providence Turnpike, Norwood, Massachusetts 02062 Search for other works by this author on: GSW Google Scholar Harold Magistrale; Harold Magistrale bResearch Division, FM Global, 1151 Boston‐Providence Turnpike, Norwood, Massachusetts 02062 Search for other works by this author on: GSW Google Scholar Guihua Chen; Guihua Chen aKey Laboratory of Active Tectonics & Volcano, Institute of Geology, China Earthquake Administration, Beijing 100029, China, chengjiajc@gmail.com Search for other works by this author on: GSW Google Scholar Xiwei Xu Xiwei Xu aKey Laboratory of Active Tectonics & Volcano, Institute of Geology, China Earthquake Administration, Beijing 100029, China, chengjiajc@gmail.com Search for other works by this author on: GSW Google Scholar Bulletin of the Seismological Society of America (2017) 107 (5): 2490–2500. https://doi.org/10.1785/0120170102 Article history first online: 27 Sep 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Jia Cheng, Yufang Rong, Harold Magistrale, Guihua Chen, Xiwei Xu; An Mw‐Based Historical Earthquake Catalog for Mainland China. Bulletin of the Seismological Society of America 2017;; 107 (5): 2490–2500. doi: https://doi.org/10.1785/0120170102 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyBulletin of the Seismological Society of America Search Advanced Search Abstract China has a nearly 3000‐year‐long earthquake record listed in various Chinese earthquake catalogs. The magnitudes in those catalogs are expressed in surface‐wave magnitude Ms⁠. However, modern seismic‐hazard analysis prefers earthquake catalogs in moment magnitude Mw⁠. Here, we compile a homogeneous Mw‐based historical earthquake catalog based on three Chinese earthquake catalogs and three global Mw catalogs. For post‐1900 earthquakes, we compare the common events with Ms in Chinese catalogs and with Mw in global catalogs, and derive Ms–Mw regression relationships using a constrained general orthogonal regression method. The regressions are performed separately over two magnitude ranges (⁠5.5≤Ms<7.0 and Ms≥7.0⁠) and three time periods (1900–1965, 1966–1975, and 1976–2015) because earthquake monitoring capabilities in China varied over those magnitudes and time ranges. We use the regression results to convert Ms magnitudes in the Chinese catalog to Mw magnitudes. For pre‐1900 events, we apply the regression results of the 1900–1965 period because the Ms values of the pre‐1900 events were converted from shaking intensity, and the Ms‐intensity relationships were derived from the post‐1900 earthquakes. We also add earthquakes from other catalogs to obtain a more complete Mw‐based catalog for China. The final catalog has about 15,700 earthquakes of Mw≥4.0. The catalog is more complete for eastern China than western China because eastern China has a much longer history of human settlement. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Probabilistic Seismic Hazard Assessment for Himalayan–Tibetan Region from Historical and Instrumental Earthquake Catalogs

Probabilistic Seismic Hazard Assessment for Himalayan–Tibetan Region from Historical and Instrumental Earthquake Catalogs

Block-and-fault dynamics modelling of the Himalayan frontal arc: Implications for seismic cycle, slip deficit, and great earthquakes

A numerical block-and-fault dynamics model (BAFD) of the Himalayan frontal arc, India is developed to understand the long-term patterns of strain accumulation and occurrences of great earthquakes in the Himalaya. The morphostructural scheme outlines twelve major crustal blocks, and external driving motions are prescribed using GPS data. The BAFD model reproduces essential features of the geodynamics and seismicity of the Himalayan frontal arc. The locations of the large synthetic earthquakes and their maximum magnitudes are consistent with the information available from the instrumental and historical earthquake catalogues. We model the evolution of the slip deficit and seismic cycles for different sections across the Himalaya frontal arc. The modelled seismic cycles are found to be varying from 700 to 2100years and are in good agreement with the return periods estimates from the recent paleoseismological studies. We notice that the accumulation of the slip deficit depends not only on the rate of shortening, rheology and structure but also on the dynamics of the confining crustal blocks. Further, we observe that tectonic motions of the Shillong plateau and Assam basin microplates play a significant role in controlling the seismicity patterns of the Bhutan block, which resulted in the decreased seismic activity, and increased rate of aseismic displacement. Thus, we infer that the regional seismicity patterns are a consequence of dynamics of the entire regional fault-and-block system rather than dynamics of individual fault. Our BAFD modelling predicts the maximum earthquake hazard associated with future large/great earthquakes for the central Himalayan gap region, which lies between the 1905 Kangra and the 2015 Gorkha earthquake ruptures, but relatively less hazard in Kashmir and Assam.

Seismotectonic Characterization of Southern Israel: Implications for CO2 Sequestration Options in the Jurassic Saline Aquifer

Earthquakes may disrupt potential carbon storage reservoirs and thus need special attention. Accordingly, this study evaluates the natural seismic activity which may disturb the long-term and large-scale CO2 storage potential of several saline aquifers in southern Israel. This work is based on the existing seismological and earthquake related data for all historical and modern earthquake catalogs. The pattern of seismicity in space and time in relation with the study area was examined. Our perspective also includes all the available neo-tectonics elements (namely geomorphic features, stress field indicators and geodetic measurements). Based on the seismotectonic of the research area, the areas relevant to CO2 storage is constrained in accordance with the following leading criteria: (1) farther than 10 km away from any Md>3 seismic event, and (2) at least 10 km away from potential surface rupture (active faults in terms of the Israeli building code) and other major fault zones. These were integrated with the previously used criteria of: (1) more than 800 m depth to the top of the aquifer, and (2) more than 100 m thickness of the capping sealing aquitard. These outcomes are presented on a summary map, an effective way to explain this process and outcomes to the decision makers.

Earthquake recurrence in NW and central Himalaya

In this study we compare Himalayan seismic moment release estimates derived from strain rate observations with those derived from large historical earthquakes, and to this end we use a reassessed catalogue of historical earthquakes from western and central Himalaya since the beginning of the 16th century. We have computed seismic moment rates within six contiguous segments along the Himalayan arc and compared these, using Kostrov’s formula, with moment rates computed from recent global strain rate estimates and regional studies. While the ratios between strain-based moment-rate estimates and those inferred from observed seismicity vary significantly between the segments, we find on the average consistently larger strain-based values by about a factor of two, based on seismicity from the last 515years. The moment-rate ratio is, however, significantly reduced when shorter catalogues are used, to 1.28 for the last 215years and to 1.05 for the last 115years, which is an almost perfect match. The possible inclusion of afterslip in the model would further improve the 515-year match. This is indicating that a significant part of the difference, possibly most of it, is likely to be caused by incompleteness of the longer earthquake catalogue, possibly combined with underestimated magnitudes. The difference between geodetic and seismic estimates for the more complete part of the catalogue is smaller than previously reported along the western Himalayan frontal thrust. In fact, the only region where a significant moment-rate difference is found in our study is in SE Himachal Pradesh. In terms of seismic hazard it is found that the moment rate reduction of about a factor of two, when going from 115 to 515years, leads to a reduction in the 475-year PGA of about 26%. It is also found that using 50years of USGS seismicity data between 1963 and 2012 leads to a 40% lower hazard as compared to using moment release for the last 115years.

Extension rates across the northern Shanxi Grabens, China, from Quaternary geology, seismicity and geodesy

Discrepancies between geological, seismic and geodetic rates of strain can indicate that rates of crustal deformation, and hence seismic hazard, are varying through time. Previous studies in the northern Shanxi Grabens, at the northeastern corner of the Ordos Plateau in northern China, have found extension rates of anywhere between 0 and 6 mm/a at an azimuth of between 95 and 180 °. In this paper we determine extension rates across the northern Shanxi Grabens from: offset geomorphological features and a variety of Quaternary dating techniques (including new IRSL and Ar-Ar ages); a Kostrov summation using a 700 year catalogue of historical earthquakes; and recent campaign GPS measurements. We observe good agreement between Quaternary, seismic and geodetic rates of strain, and we find that the northern Shanxi Grabens are extending at around 1 to 2 mm/a at an azimuth of ≈ 151 °. The azimuth of extension is particularly well constrained and can be reliably inferred from catalogues of small earthquakes. We do not find evidence for any substantial variations in extension rate through time, though there is a notable seismic moment rate deficit since 1750. This deficit could indicate complex fault interactions across large regions, aseismic accommodation of deformation, or that we are quite late in the earthquake cycle with the potential for larger earthquakes in the relatively near future.

Update and sensitivity analysis of the neo-deterministic seismic hazard assessment for Egypt

The main goal of this work is to provide an update on the seismic hazard maps available for Egypt that incorporates the results of recent studies, i.e. revised historical earthquake catalogs, morphostructural zonation data (MZ), revised focal mechanism solutions and mechanical models of the lithospheric structure. This is done within the framework of the neo-deterministic seismic hazard assessment (NDSHA) procedure that may effectively accommodate any reliable new information to adequately compute the earthquake ground motion maps (i.e. PGA, PGV and PGD). Furthermore, with the set of relevant scenario earthquakes, this work provides a large dataset of synthetic seismograms, particularly important for the areas that suffer from the endemic lack of useful strong motion time histories such as Egypt, setting the base toward detailed and comprehensive seismic microzonation studies. NDSHA aims to supply an envelope value, in other words a value that should not be exceeded, therefore it is immediately falsifiable and verifiable.A sensitivity analysis based on the different ground motion maps, computed adopting different (a) models for the earthquake source process, (b) mechanical models of the crust and (c) mapmaker's preconceptions (e.g. different seismotectonic models), is provided. The maps of difference and ratio between various ground motion maps computed for different variants are shown and discussed in order to explore the influence of using various input models. The results provide the potential users with an adequate spectrum of choices and reliably assess and clearly communicate the possible uncertainties. The availability of a wide spectrum of hazard maps is a prerequisite to supply valuable information for the significant improvement of a seismic code.

明応七年六月十一日（1498年6月30日）の日向灘大地震は存在しなかった

A large earthquake (M7.0~7.5) in Hyuga-nada Sea on the east side of Kyushu along Nankai trough in Mi-no-koku (approximately 9-11 a.m.) on June 30th, 1498 on Julian calendar, which was based on the descriptions about serious earthquake damage in Kyushu in the war chronicle Kyushu-gunki, has been accepted by many seismologists as the 1498 Meio Hyuga-nada earthquake. Kyushu-gunki is one of the popular novels which was written more than 100 years after the 1498 event. The damage descriptions have been used to estimate the location of this earthquake without evaluating the reliability. In this study, in order to assess credibility of the description, we carefully examined writing process of Kyushu-gunki and damage descriptions in this war chronicle. Our findings are summarized as follows: (1) Kyushu-gunki was completed in the current Saga prefecture (northwestern part of Kyushu) in 1607, hence the writers’ experience of the contemporary 1596 destructive earthquake in northeastern Kyushu might have influenced the description of the damage of 1498 earthquake; (2) Damage descriptions of Kyushu-gunki were generic without location information and most of them were cited from descriptions of damage in Kyoto due to the large earthquake on Aug. 6th, 1185 in the war chronicle Gempei-josui-ki; (3) Origin time (Mi-no-koku) of this event is described only in Kyushu-gunki and it is close to that of the great Tokai earthquake on Sep. 11th, 1498 (Tatsu-no-koku: approximately 7-9 a.m.); (4) The chapter of the earthquake damage also includes serious famine in Kyushu in 1503 and pains of people by many disasters, making this chapter a stage setting for later stories. To make a story of the war chronicle more interesting, writers seem to have created fictitious story of serious damage due to a large earthquake in Kyushu based on old war chronicles and some records of the great Tokai earthquake. Therefore, we concluded that the 1498 Meio Hyuga-naga earthquake is a fake earthquake and it should be deleted from Japanese historical earthquake catalog. Other documents in Kyoto and Nara recorded an earthquake in Saru-no-koku (approximately 3-5 p.m.) on June 30th, 1498, but the location and magnitude are not clear.

A Statistical Investigation on a Seismic Transient Occurred in Italy Between the 17th and 20th Centuries

According to the historical earthquake catalog of Italy, the country experienced a pulse of seismicity between the 17th century, when the rate of destructive events increased by more than 100%, and the 20th century, characterized by a symmetric decrease. In the present work, I performed a statistical analysis to verify the reliability of such transient, considering different sources of bias and uncertainty, such as completeness and declustering of the catalog, as well as errors on magnitude estimation. I also searched for a confirmation externally to the catalog, analyzing the correlation with the volcanic activity. The similarity is high for the eruptive history of Vesuvius, which agrees on both the main rate changes of the 17th and 20th centuries and on minor variations in the intermediate period. Of general interest, beyond the specific case of Italy, the observed rate changes suggest the existence of large-scale crustal processes taking place within decades and lasting for centuries, responsible for the synchronous activation/deactivation of remote, loosely connected faults in different tectonic domains. Although their origin is still unexplained (I discuss a possible link with the climate changes and the consequent variations of the sea level), their existence and long lasting is critical for seismic hazard computation. In fact, they introduce a hardly predictable time variability that undermines any hypothesis of regularity of the earthquake cycle on individual faults and systems of interconnected faults.

Evaluation of the macroseismic intensities triggered by the January/February 2014 Cephalonia, (Greece) earthquakes based on ESI-07 scale and their comparison to 1867 historical event

On January 26th and February 3rd, 2014, two earthquakes occurred onshore the island of Cephalonia inducing severe environmental effects. The main types of earthquake-induced failures were liquefaction and slope failures and were mainly widespread at the western and central part of the island at Paliki peninsula. Although the fact that the generated strong motions by the second event were the highest ever recorded in Greece, medium severity structural damages were induced. Few days after the occurrence of the events, two post-earthquake field surveys took place in order to document the generated environmental effects. By taking into account these field observations, it was decided to evaluate the macroseismic intensity of the February 3rd, 2014 earthquake by applying the ESI-07 scale. As an outcome, the epicentral intensity of Feb. 3rd, 2014 was evaluated as VII ESI-07 by taking into account the total affected area. Furthermore, as it is pointed out in primary contemporary sources and seismic catalogues, similar environmental failures such as liquefaction phenomena at coastal areas and large scale rockfalls were triggered by historical earthquakes at the island of Cephalonia. The most accurately described effects are the ones triggered by the 1867 earthquake. Therefore, it was decided to assess the macroseismic intensities of this historical event based on the ESI-07 scale and compare it with the relevant ones of Feb 3rd, 2014 event. As an outcome, it is concluded that similar intensities were assessed for both events, VIII ESI-07 for 1867 event and VII ESI-07 for the February 2014 one, despite the fact that the relevant earthquake magnitudes strongly differ. Outlining the results of this study, it is reconfirmed the importance of the recording and documentation of earthquake environmental effects in order to maintain the consistency with the historical earthquake catalogues. Moreover, a re-evaluation of historical earthquake magnitudes at the area of Cephalonia island could be realized in order to accurately update the seismic hazard.

Possibility of the Late Holocene uplift in the southeastern coast of Yeongil Bay, Korean Peninsula: Evidence from an exposed sea cave

Marine terraces have developed intermittently along the southeastern shore of Yeongil Bay on the Korean Peninsula. These terraces have been classified into four levels: 4–5, 14–15, 25–27, and 35m above sea level. Three sea caves formed in the cliffs of the 26-m marine terrace on the headland. One of these caves is filled with sediments >3.4-m-thick, consisting of well-sorted beach pebbles and sand or disorganized ignimbrite breccia. The uppermost sediments dating to 1680–1820 at ca. 4m above the present sea level may indicate a former shoreline. According to the historical earthquake catalog of the Korean Peninsula, the three largest earthquakes (Mw 6.2) were recorded in 1643 and 1681. The catalog suggests that two earthquakes in 1643 were felt in the southern area of the Korean Peninsula, in locations such as Hapcheon, Daegu, Andong, Kimhae, and Ulsan. The 1681 Yangyang earthquake caused shaking over the entire Korean Peninsula, and is thought to have been Korea’s largest historical earthquake. We concluded that 4-m uplifting of the sea cave beach sediments could be explained by the highest seismicity and the three largest historical earthquakes in the 1600s. It is believed that the 1681CE main earthquake, including its foreshocks and aftershocks, resulted in reactivation of the Ocheon fault, which may be the main cause of sea cave uplifting on the Masan-ri coast.

Seismotectonic database of Turkey

Turkey is located in one of the most seismically active regions in the world. Characterizing seismic source zones in this region requires evaluation and integration of geological, geophysical, seismological and geodetical data. This first seismotectonic database for Turkey presented herein was prepared, under the framework of the National Earthquake Strategy and Action Plan—2023. The geographic information system (GIS)-based database includes maps of active faults, catalogues of instrumental and historical earthquakes, moment tensor solutions and data on crustal thickness. On the basis of these data, 18 major seismotectonic zones were delineated for Turkey and the surrounding region. The compilation and storage of the seismotectonic data sets in a digital GIS will allow analyses and systematic updates as new data accrete over time.

Enhanced stress and changes to regional seismicity due to the 2015 Mw 7.8 Gorkha, Nepal, earthquake on the neighbouring segments of the Main Himalayan Thrust

In this study we evaluate stress evolution and change in seismic hazard after the 2015 Gorkha earthquake sequence. We take a methodology usually used in areas with well-established seismic monitoring and apply it to an area with a sparse dataset and a limited time observation window. Our goal is to validate this approach as a rapid response tool for seismic forecasting after large earthquakes. We propose a long-term seismic forecasting model of the Main Himalayan Thrust using the historical earthquake catalogue and regional paleo-seismicity. Through application of the rate-and-state friction model, we evaluate short-term rate evolution after the Gorkha earthquake. The long elapsed time since the last megathrust event and the mainshock coseismic stress increase on the Main Himalayan Thrust suggest high seismic potential in the Lalitpur and Lamjung areas along the fault system. We also calculate the stress change on optimally oriented planes in the region and model the regional seismicity rate using a smoothing kernel method and seismicity since 1921. The location of the consequent earthquakes coincides with areas of high background seismicity rate and areas where stress was enhanced by the Mw 7.8 mainshock and Mw 7.3 aftershock. We model the change of seismic rate over time and project a fast decrease, due to the short aftershock duration assumption we use.

Toward a CO2 sequestration project in the Jurassic saline aquifer of southern Israel: Seismotectonic characterization

Earthquakes may disrupt potential carbon storage reservoirs and thus need special attention. Accordingly, this study evaluates the natural seismic activity which may disturb the long-term and large-scale CO2 storage potential of several saline aquifers in southern Israel. This work is part of the characterization of the proposed sequestration sites in Israel and is based on all the existing seismological and earthquake related data. First all the historical and modern earthquake catalogs were gathered and the pattern of seismicity in space and time in relation with the study area was examined. Our perspective is then extended beyond the limited term exhibited by these records, and resorted to all the available neo-tectonics elements, namely geomorphic features, stress field indicators and geodetic measurements.Based on the seismotectonics of the research area, the areas relevant to CO2 storage is constrained in accordance with the following leading criteria: (1) farther than 10km away from any Md>3 seismic event, and (2) at least 10km away from potential surface rupture (active faults in terms of the Israeli building code) and other major fault zones. These were integrated with the additional criteria of: (1) more than 800m depth to the top of the aquifer, and (2) more than 100m thickness of the capping sealing aquitard, that were determined previously (Calvo and Gvirtzman, 2013, IJGGC 14: 25–38). Overall, the area relevant for CO2 storage in Israel is reduced to about 4250km2. Three proposed storage sites were examined and found to be located well within the reduced area of interest (AOI), at least 36km away from the nearest recorded Md>3.0 earthquake. These outcomes are presented on a summary map, an effective way to explain this process and outcomes to the decision makers.Henceforth, there is the need to set threshold criteria that will guide the collecting of the missing data, fill the knowledge gaps and direct future investigations. Such are, for example, the accurate monitoring of natural weak seismicity and the state of stress within the proposed sites. Hazards that cannot be measured directly will need modeling and sensitivity analysis such as the potential role of the present day stress field and induced seismicity, whether they are capable of damaging the integrity of the potential aquitard. These actions will allow determining whether the proposed sites do meet with the necessary requirements and predicting the behavior of the reservoir rocks under different conditions until failure and escape of the sequestrated material.

ZEMĚTŘESENÍ V HOSTĚRADICÍCH V ČERVNU 2014

Southern Moravia – a southeastern part of the Czech Republic at the contact of the Bohemian Massif and the Carpathian Foredeep – is one of the regions with the lowest seismic activity in the Czech Republic. Reports on historical earthquakes in this area are sporadic and poorly evidenced, many of the messages are in fact observations of earthquakes originating mainly in Austria. Instrumental seismic monitoring in southern Moravia commenced in 1995. Thereafter only three local earthquakes were observed – magnitude 2.5 event near Hostěradice in 2000, perhaps induced event near Uhřice in 2003 with magnitude of 0.7 and magnitude 1.4 earthquake near Božice in 2006.A sequence of four weak earthquakes in June 2014 is only the fourth occurrence of earthquakes in southern Moravia since the beginning of instrumental measurements. Events originated near Hostěradice (SE margin of the Bohemian Massif), 40 km southwest of Brno. The strongest event reaching local magnitude of 2.0 occurred on June 1, 2014 at 00:43 UTC. It was felt by people close to the epicentre with a macroseismic intensity 4 European Macroseismic Scale EMS-98. A temporary seismic station was immediately installed in the epicentral area. The station recorded two of four shocks and helped to confi rm a focus position of the sequence: 48.95° N 16.24° E, depth 3 km.In 2014 a review of historical earthquakes in this region was conducted using new catalogues of historical earthquakes in neighboring countries in order to avoid confusion between local and regional phenomena. Some new information sources were found. In any case, historical earthquakes in this region are very rare and most of them are poorly substantiated.

Erratum: Aseismic transient driving the swarm-like seismic sequence in the Pollino range, Southern Italy

Tectonic earthquake swarms challenge our understanding of earthquake processes since it is difficult to link observations to the underlying physical mechanisms and to assess the hazard they pose. Transient forcing is thought to initiate and drive the spatio-temporal release of energy during swarms. The nature of the transient forcing may vary across sequences and range from aseismic creeping or transient slip to diffusion of pore pressure pulses to fluid redistribution and migration within the seismogenic crust. Distinguishing between such forcing mechanisms may be critical to reduce epistemic uncertainties in the assessment of hazard due to seismic swarms, because it can provide information on the frequency-magnitude distribution of the earthquakes (often deviating from the assumed Gutenberg-Richter relation) and on the expected source parameters influencing the ground motion (for example the stress drop). Here we study the ongoing Pollino range (Southern Italy) seismic swarm, a long-lasting seismic sequence with more than five thousand events recorded and located since October 2010. The two largest shocks (magnitude M-w = 4.2 and M-w = 5.1) are among the largest earthquakes ever recorded in an area which represents a seismic gap in the Italian historical earthquake catalogue. We investigate the geometrical, mechanical and statistical characteristics of the largest earthquakes and of the entire swarm. We calculate the focal mechanisms of the M-l > 3 events in the sequence and the transfer of Coulomb stress on nearby known faults and analyse the statistics of the earthquake catalogue. We find that only 25 per cent of the earthquakes in the sequence can be explained as aftershocks, and the remaining 75 per cent may be attributed to a transient forcing. The b-values change in time throughout the sequence, with low b-values correlated with the period of highest rate of activity and with the occurrence of the largest shock. In the light of recent studies on the palaeoseismic and historical activity in the Pollino area, we identify two scenarios consistent with the observations and our analysis: This and past seismic swarms may have been 'passive' features, with small fault patches failing on largely locked faults, or may have been accompanied by an 'active', largely aseismic, release of a large portion of the accumulated tectonic strain. Those scenarios have very different implications for the seismic hazard of the area.