scholarly journals Macroseismic intensity investigation of the November 2014, M=5.7, Vrancea (Romania) crustal earthquake

2016 ◽  
Vol 59 (5) ◽  
Author(s):  
Angela Petruta Constantin ◽  
Iren Adelina Moldovan ◽  
Andreea Craiu ◽  
Mircea Radulian ◽  
Constantin Ionescu
Keyword(s):  
Seismic Event ◽  
Main Shock ◽  
Focal Depth ◽  
Earthquake Occurrence ◽  
Epicentral Area ◽  
Ground Shaking ◽  
Crustal Earthquake ◽  
Historical Times ◽  
Vrancea Seismogenic Region ◽  
North Latitude

On November 22, 2014 at 21:14:17 local hour (19:14:17 GMT) a  M<sub>L</sub>=5.7 crustal earthquake occurred in the area of Marasesti city of Vrancea county (Romania) - the epicenter was located at north latitude 45.87° and east longitude 27.16°, with a focal depth of 39 km. This earthquake is the main shock of a sequence that started with this and lasted until the end of January. During the sequence, characterized by the absence of foreshocks, a number of 75 earthquakes were recorded in 72 hours, the largest of which occurred in the same day with the main shock, at 22:30 (M<sub>L</sub>= 3.1). The crustal seismicity of Vrancea seismogenic region is characterized by moderate earthquakes with magnitudes that have not exceeded M<sub>W</sub> 5.9, this value being assigned to an earthquake that occurred in historical times on March 1, 1894 (Romplus catalogue). Immediately after the 2014 earthquake occurrence, the National Institute for Earth Physics (NIEP) sent macroseismic questionnaires in all affected areas, in order to define the macroseismic field of ground shaking. According to macroseismic questionnaires survey, the intensity of epicentral area reached VI MSK, and the seismic event was felt in all the extra-Carpathian area. This earthquake caused general panic and minor to moderate damage to the buildings in the epicentral area and the northeast part of country. The main purpose of this paper is to present the macroseismic map of the earthquake based on the MSK-64 intensity scale.

scholarly journals Technologies and new approaches used by the INGV EMERGEO Working Group for real-time data sourcing and processing during the Emilia Romagna (northern Italy) 2012 earthquake sequence

2012 ◽  
Vol 55 (4) ◽  
Author(s):  
Giuliana Alessio ◽  
Laura Alfonsi ◽  
Carlo Alberto Brunori ◽  
Pierfrancesco Burrato ◽  
Giuseppe Casula ◽  
...  
Keyword(s):  
Seismic Event ◽  
Main Shock ◽  
Northern Italy ◽  
Earthquake Activity ◽  
Seismic Sequence ◽  
Time Data ◽  
Broad Area ◽  
Epicentral Area ◽  
Po Plain ◽  
Real Time Data

<p>On May 20, 2012, a Ml 5.9 seismic event hit the Emilia Po Plain, triggering intense earthquake activity along a broad area of the Po Plain across the provinces of Modena, Ferrara, Rovigo and Mantova (Figure 1). Nine days later, on May 29, 2012, a Ml 5.8 event occurred roughly 10 km to the SW of the first main shock. These events caused widespread damage and resulted in 26 victims. The aftershock area extended over more than 50 km and was elongated in the WNW-ESE direction, and it included five major aftershocks with 5.1 ≤Ml ≤5.3, and more than 2000 minor events (Figure 1). In general, the seismic sequence was confined to the upper 10 km of the crust. Minor seismicity with depths ranging from 10 km to 30 km extended towards the southern sector of the epicentral area (ISIDe, http://iside.rm.ingv.it/). […]</p><br />

The 1638 earthquakes, migratory phenomena and geolinguistic consequences in Calabria

1995 ◽  
Vol 38 (5-6) ◽  
Author(s):  
G. Chiodo ◽  
I. Guerra ◽  
J. Trumper
Keyword(s):  
Urban Communities ◽  
Seismic Event ◽  
Southern Italy ◽  
Middle Eastern ◽  
Sources Of Information ◽  
Historical Sources ◽  
Epicentral Area ◽  
Damage Area ◽  
Cultural Status ◽  
Historical Times

Two disastrous earthquakes occurred in Calabria (Southern Italy) in 1638: on March 27th the first one had a destructive damage area on the Tyrrheniail side of Mid-Calabria. the second one hit the east side of the same region on June 9th. In historical times they are the most intensive seismic events in their respective epicentral areas. so that the reconstruction of their effects is very important for the analysis and assessment of seismic risk. They strongly influenced, moreover, the development of the economy and socio-cultural status of many urban communities. A study of these shocks has been carried out and has implied a thorough re-evaluation of the historical sources of information already known and the exploitation of possible new sources. The two macroseismic fields have been reconstructed: in particular that of the second seismic event, the strongest one in its epicentral area. stimulates a thorough revision of the seismotectonics of the Middle-eastern Calabria. Moreover the reconstruction of the historical facts accompanying and following the earthquakes has furnished elements that help to explain observed anomalies in the spatial distribution of Calabrian dialect phenomena.

scholarly journals TECTONIC POSITION, SISMOLOGICAL AND GEOLOGICAL MANIFESTATION OF 7 SEPTEMBER 2009 ONI?II EARTHQUAKE FOCUS ON THE SOUTHERN SLOPES OF THE GREAT CAUCASUS

2017 ◽  
Author(s):  
Е.А. Рогожин
Keyword(s):  
Main Shock ◽  
Focal Depth ◽  
Seismic Source ◽  
Epicentral Area ◽  
Strong Earthquakes ◽  
North East ◽  
The North ◽  
Tectonic Position ◽  
South Slope ◽  
Racha Earthquake

В статье приведены сейсмологические и сейсмотектонические материалы о главном толчке и афтершоках Онийского-II землетрясения 7 сентября 2009 г. с Мs = 5,8 на южном склоне Большого Кавказа. Положение облака эпицентров основного толчка и афтершоков совпадает с северной ветвью очаговой зоны Рачинского землетрясения 29.04.1991 г. с МS = 7,0, I0 = 7-8. Глубина гипоцентра основного толчка составляет 8?15 км. В качестве действующей в очаге принята пологая плоскость, погружающаяся в север – северо-восточном направлении. Тип подвижки по такой плоскости – надвиг с компонентами правостороннего сдвига. Сейсмодислокации носили вторичный, гравитационный характер. Результаты палеосейсмологические исследований, проведенных в восточной части эпицентральной области, Рачинского землетрясения, показали, что в этом сейсмической очаге и раньше происходили сильне сейсмические толчки. Согласно полученным данням возраст предыдущего сильного землетрясения в Рача-Джавской зоне (т. е. до 1991 г.) – около 2000 лет назад. Еще одно, болем древнее событие произошло около 6000 лет назад. Период повторяемости сильних землетрясений, подобных катастрофе 1991 г., таким образом, составляет в среднем 2000-3000 лет. The article provides seismological and seismotectonic materials about the main shock and aftershocks of the Oni-II earthquake of 7 September 2009, with MS = 5,8 on the South slope of the Greater Caucasus. The position of the cloud of epicenters of the main shock and aftershocks coincides with the northern branch of the focal zone of 29.04.1991 Racha earthquake, MS = 7,0, I0 = 7?8. The focal depth of the main shock is 8 to 15 km. As the active in the focus adopted the sloping plane, plunging to the North – North-East direction. Type progress on such a plane – thrust with component of right-lateral strike-slip. Seismodislocationswere of secondary gravitational nature. The results of paleoseismological studies conducted in the Eastern part of the epicentral area of the Racha earthquake, showed that this seismic source the strong seismic shocks happened before. According to the obtained data, the age of the previous strong earthquake in the Racha – Dzhava zone (i.e., before 1991) – about 2000 years ago. Another, more ancient event occurred about 6,000 years ago. The recurrence period of strong earthquakes, similar to the disaster of 1991, thus, is an average of 2000?3000 years.

scholarly journals Modeling of the stress-strain state in the earthquake epicenter area (Kumamoto Earthquake, Japan), 16.04.2016 M 7.3

2017 ◽  
pp. 48-54
Author(s):  
V. N. Morozov ◽  
A. I. Manevich
Keyword(s):  
Elastic Modulus ◽  
Strain State ◽  
Main Shock ◽  
Depth Interval ◽  
Stress Strain ◽  
Epicentral Area ◽  
Kumamoto Earthquake ◽  
Stress Strain State ◽  
Crustal Earthquake ◽  
North East

On the 16th of April, 2016, a strong earthquake with M 7,3 occurred in the Kumamoto prefecture (Kyushu, Japan). This earthquake is the strongest in the last 30 years in this area. For a day before the main shock, two foreshocks with M 6,4 were registered. For seven days after the main shock, aftershocks activity spread to the north-east and south-west, most of the hypocentres of the aftershocks with M 6,4 were localized within the seismogenic layer in the depth interval from 5 to 10 km. The authors have modeled a stress-strain state (SSS) of the epicentral area be fore the earthquake and after it (after the formation of the main fault). For this purpose, a software package is used, that allows 2-D formulation (plane strain condition), for modeling SSS block heterogeneous geological environment, disrupted by a system of tectonic faults. The faults are modeled in the form of extended zones of the dispersed geomaterial, which elastic modulus are significantly lower than the elastic modulus of the environmental media. A structural-tectonic scheme of the Kumamoto earthquake area is used. An analysis of the results of SSS modeling has been done for the area 30x40 km before and after the earthquake. It is shown that the area and magnitude of the stress intensity in anomalous zones are the predictive signs of the location and intensity of a possible strong crustal earthquake, and the vector of the rapid decrease in the potential energy of deformation could be a guide for the most probable direction of tectonic rupture during a crustal earthquake. The results received can be useful in a deterministic approach to seismic hazard assessment and carrying out the geophysical observations focused on the forecast of the strong crustal earthquakes in the continental areas.

scholarly journals The ShakeMaps of the Amatrice, M6, earthquake

2016 ◽  
Vol 59 ◽  
Author(s):  
Licia Faenza ◽  
Valentino Lauciani ◽  
Alberto Michelini
Keyword(s):  
Ground Motion ◽  
Data Exchange ◽  
Main Shock ◽  
Central Italy ◽  
Strong Motion ◽  
Rupture Directivity ◽  
Time Data ◽  
Epicentral Area ◽  
Ground Shaking ◽  
Motion Data

In this paper we describe the performance of the ShakeMap software package and the fully automatic procedure, based on manually revised location and magnitude, during the main event of the Amatrice sequence with special emphasis to the M6 main shock, that struck central Italy on the 24th August 2016 at 1:36:32 UTC. Our results show that the procedure we developed in the last years, with real-time data exchange among those institutions acquiring strong motion data, allows to provide a faithful description of the ground motion experienced throughout a large region in and around the epicentral  area. The prompt availability of the rupture fault model, within three hours after the earthquake occurrence, provided a better descriptions of the level of strong ground motion throughout the affected area.  Progressive addition of  station data and  manual verification of the data insures improvements in the description of the experienced ground motions.  In particular, comparison between the MCS intensity shakemaps and preliminary field macroseismic reports show favourable similarities.  Finally the overall  spatial pattern of the ground motion of the main shock is consistent with reported rupture directivity toward NW and reduced levels of ground shaking toward SW probably linked to the peculiar source effects of the earthquake.

A database of the environmental effects associated to the December 29th, 2020 Mw 6.4 Petrinja earthquake (Croatia)

2021 ◽  
Author(s):  
Matija Vukovski ◽  
Marko Budić ◽  
Marko Špelić ◽  
Josip Barbača ◽  
Nikola Belić ◽  
...  
Keyword(s):  
Environmental Effects ◽  
Focal Depth ◽  
Lateral Spreading ◽  
Second Phase ◽  
Surface Rupture ◽  
Maximum Displacement ◽  
Epicentral Area ◽  
Ground Shaking ◽  
Seismogenic Source ◽  
Surface Ruptures

&lt;p&gt;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.&lt;br&gt;The Croatian Geological Survey (HGI-CGS) conducted extensive geological and geodetic surveys starting a few hours following the main shock to measure the earthquake&amp;#8217;s effects,&lt;br&gt;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).&lt;br&gt;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).&lt;br&gt;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.&lt;br&gt;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 &amp;#8220;surface rupture&amp;#8221;, &amp;#8220;liquefaction&amp;#8221;, or &amp;#8220;ground-shaking&amp;#8221; potential.&lt;/p&gt;

scholarly journals The Zagreb (Croatia) M5.5 Earthquake on 22 March 2020

Geosciences ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 252 ◽  
Author(s):  
Snježana Markušić ◽  
Davor Stanko ◽  
Tvrtko Korbar ◽  
Nikola Belić ◽  
Davorin Penava ◽  
...  
Keyword(s):  
Structural Engineering ◽  
Main Shock ◽  
Residential Buildings ◽  
Tectonic Setting ◽  
Time Lapse ◽  
Earthquake Sequence ◽  
Epicentral Area ◽  
Local Soil ◽  
Seismic Amplification ◽  
Zagreb Area

On 22 March 2020, Zagreb was struck by an M5.5 earthquake that had been expected for more than 100 years and revealed all the failures in the construction of residential buildings in the Croatian capital, especially those built in the first half of the 20th century. Because of that, extensive seismological, geological, geodetic and structural engineering surveys were conducted immediately after the main shock. This study provides descriptions of damage, specifying the building performances and their correlation with the local soil characteristics, i.e., seismic motion amplification. Co-seismic vertical ground displacement was estimated, and the most affected area is identified according to Sentinel-1 interferometric wide-swath data. Finally, preliminary 3D structural modeling of the earthquake sequence was performed, and two major faults were modeled using inverse distance weight (IDW) interpolation of the grouped hypocenters. The first-order assessment of seismic amplification (due to site conditions) in the Zagreb area for the M5.5 earthquake shows that ground motions of approximately 0.16–0.19 g were amplified at least twice. The observed co-seismic deformation (based on Sentinel-1A IW SLC images) implies an approximately 3 cm uplift of the epicentral area that covers approximately 20 km2. Based on the preliminary spatial and temporal analyses of the Zagreb 2020 earthquake sequence, the main shock and the first aftershocks evidently occurred in the subsurface of the Medvednica Mountains along a deep-seated southeast-dipping thrust fault, recognized as the primary (master) fault. The co-seismic rupture propagated along the thrust towards northwest during the first half-hour of the earthquake sequence, which can be clearly seen from the time-lapse visualization. The preliminary results strongly support one of the debated models of the active tectonic setting of the Medvednica Mountains and will contribute to a better assessment of the seismic hazard for the wider Zagreb area.

scholarly journals Neogene-Quaternary tectonic regime and macroseismic observations in the Tyrnavos-Elassona broader epicentral area of the March 2021, intense earthquake sequence

2021 ◽  
Vol 58 ◽  
pp. 200
Author(s):  
Dimitrios Galanakis ◽  
Sotiris Sboras ◽  
Garyfalia Konstantopoulou ◽  
Markos Xenakis
Keyword(s):  
Normal Fault ◽  
Fault Scarp ◽  
Focal Mechanisms ◽  
Fault System ◽  
Spatiotemporal Evolution ◽  
Surface Rupture ◽  
Alluvial Deposits ◽  
Epicentral Area ◽  
Ground Shaking ◽  
Macroseismic Observations

On March 3, 2021, a strong (Mw6.3) earthquake occurred near the towns of Tyrnavos and Elassona. One day later (March 4), a second strong (Mw6.0) earthquake occurred just a few kilometres toward the WNW. The aftershock spatial distribution and the focal mechanisms revealed NW-SE-striking normal faulting. The focal mechanisms also revealed a NE-SW oriented extensional stress field, different from the orientation we knew so far (ca. N-S). The magnitude and location of the two strongest shocks, and the spatiotemporal evolution of the sequence, strongly suggest that two adjacent fault segments were ruptured respectively. The sequence was followed by several coseismic ground deformational phenomena, such as landslides/rockfalls, liquefaction and ruptures. The landslides and rockfalls were mostly associated with the ground shaking. The ruptures were observed west of the Titarissios River, near to the Quaternary faults found by bore-hole lignite investigation. In the same direction, a fault scarp separating the alpidic basement from the alluvial deposits of the Titarissios valley implies the occurrence of a well-developed fault system. Some of the ground ruptures were accompanied by extensive liquefaction phenomena. Others cross-cut reinforced concrete irrigation channels without changing their direction. We suggest that this fault system was partially reactivated, as a secondary surface rupture, during the sequence as a steeper splay of a deeper low-to-moderate angle normal fault.

The island of Hawaii earthquakes of November 29, 1975: Strong-motion data and damage reconnaissance report

1977 ◽  
Vol 67 (2) ◽  
pp. 493-515
Author(s):  
Christopher Rojahn ◽  
B. J. Morrill
Keyword(s):  
Local Time ◽  
Structural Damage ◽  
Strong Motion ◽  
Maximum Acceleration ◽  
Epicentral Area ◽  
Ground Shaking ◽  
Motion Data ◽  
Large Sector ◽  
Threshold Duration ◽  
Strong Ground

Abstract Two earthquakes occurred on the island of Hawaii on November 29, 1975, a magnitude (Ms) 5.7 event at 0335 (local time) and a magnitude (Ms) 7.2 event at 0447. During the larger event, a maximum acceleration of 0.22 g was recorded in the southern part of Hilo, 43 km north of the epicenter. A 0.05 g threshold duration of 13.7 sec was measured for the same component. Smaller amplitude accelerograph records were obtained at two other locations on the island along with four seismoscope records. During or subsequent to the larger event, a large sector of the southeastern coastline subsided by as much as 3.5 meters. A tsunami generated by the larger event caused at least one death (one person also missing), injury to 28 persons, and significant structural and nonstructural damage. Only scattered evidence of strong ground shaking was observed in the epicentral area, and most of the several dozen nearby structures sustained little or no structural damage from ground shaking. In Hilo, 45 km north of the Ms = 7.2 epicenter, structural and nonstructural damage was slight to moderate but more extensive than elsewhere on the island.

The Godavari Valley earthquake sequence of April 1969

1970 ◽  
Vol 60 (2) ◽  
pp. 601-615 ◽  
Author(s):  
Harsh K. Gupta ◽  
Indra Mohan ◽  
Hari Narain
Keyword(s):  
Main Shock ◽  
Focal Depth ◽  
Earthquake Sequence ◽  
Total Strain ◽  
Type I ◽  
Aftershock Area ◽  
Macroseismic Effects ◽  
Godavari Valley

abstract The Godavari Valley earthquake sequence of April 1969 has been studied in detail. The (Sg − Pg) and the (Pg − Pn) intervals have been used for estimating the extent of aftershock area and focal depth variations respectively. The main shock of magnitude 5.7 was followed by a number of aftershocks which are related by the function Log N = a + b M. The value of b is found to be −0.51. The main shock of April 13 accounted for 70 per cent of the total strain released. This sequence belongs to Type I of Mogi's classification. The macroseismic effects are also discussed briefly.

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