Ayu-Dag and other evidence of the Wrath of the Lord

An unusual shape of a laccolith in the southern coastal part of the Crimea, which, when seen from a distance, resembles a huge beast bending its muzzle to the water, could well determine its name, i. e. Ayu-Dag (Crimean Tatar — Ayuv Dağ, i. e. the Bear Mount). The legend about this toponym allegorically tells about a catastrophic earthquake, which the Crimean peninsula was exposed to in the Middle Ages. This natural phenomenon was reflected in three other local legends about the Castel Mount, Yalta and Sunen-Kaya. Most likely, this calamity took place during the first war between Kaffa and Theodoro, in October-November of 1423. In many ways, it can be compared with the notorious Yalta earthquake of 1927. The archaeological works on a number of medieval sites in the region can give a good idea of the consequences of the 15th-century seismic event, which embodied the wrath of the Lord: a monastery on the south-eastern slope of the Ayu-Dag, Funa’s fort, Kalamita and Cembalo, and Basilica in Eski-Kermen.

THE SEPTEMBER 2, 2015, КR=14.0, Mw=5.1, I0=7–8 TALLAY EARTHQUAKE at the NORTH-EASTERN FLANK of the BAIKAL RIFT

We consider September 2, 2015, Mw=5.1 Tallay earthquake occurred in the previously aseismic area of the North-Muya Ridge adjoining to the Muya-Kuanda basin from the north. Instrumental and macroseismic data on this seismic event are presented. Its seismic moment tensor is calculated from surface wave amplitude spectra. New data on strong ground motions are obtained within the north-eastern flank of the Baikal rift. The Tallay earthquake is found to be connected with seismogenic renewal of the second-order multidirectional faults activated in the rift stress field.

SEISMICITY of AZERBAIJAN and ADJACENT TERRITORIES in 2015

In 2015, the network of Azerbaijan seismic stations included 35 digital stations, which continued to operate unchanged. The set of parameters determined for estimating the earthquake magnitude has decreased – determination of the MPVA magnitude and КР energy class has ceased. Only the local magnitude MLАзр was measured. The total number of earthquakes recorded by the Azerbaijan network of stations in 2015 amounted to 6419, however, only 128 of them with MLАзр3.0 are given in the catalogue of earthquakes of Azerbaijan published in the Appendix to this article. Seismic activity in the study area remained unchanged. The released seismic energy changed insignificantly compared to its value in 2014 and was close to the background level for the period 1993–2014. The increase in the number of earthquakes of the representative level (K≥8.6, MLАзр≥2.8) in comparison with the long-term average annual value is due to aftershocks of earthquakes on January 26 with MLАзр=4.9, June 3 with MLАзр=4.6, and September 4 with MLАзр=5.9. The 2015 most significant seismic event on the territory of the Republic was the earthquake on September 4 with MLАзр=5.9 and seismic intensity at the epicenter of I0=7.

SEISMICITY of the TERRITORY of BELARUS in 2015

An annual review of the seismicity in the territory of Belarus based on the data of two analog (operated in the first half-year) and seventeen digital stations is presented. A total of 80 events with Кd=4.6–8.4 were recorded all of them being confined to the southern part of the territory, the Soligorsk mining area included. The map of all the event epicenters for 2015 is given. The table of the distribution of the seismic events by their energy classes and seismic energy in months is presented. The maximum values of the seismic energy release fell in August, and the maximum number of the events was observed in July. The level of the seismic energy released in 2015 is the same as in 2014 but 2.18 times lower than its long-time average value for 1983–2014. The number of the events in 2015 is 1.4 times more than their number in 2014 and 1.86 times more than the Nср value for the previous 32 years. The distribution of the earthquakes in the depth intervals layers showed that the earthquake foci are mostly located in the upper 20 km part of the Earth’s crust. However, the foci of 47 earthquakes are located at depths above 10 km. The distribution of all the events in 2015 is represented in real-time. The quiet seismic periods and seismic activation periods were determined. The distribution of the seismic events in the hourly intervals showed the periods of the increase of the seismic events number. The maximum and minimum values N in the seismic event distribution by the days of the week were determined.

Seismic and Geodetic Observations of Accelerated Sliding at Haupapa/Tasman Glacier, New Zealand

<p>Rain-induced accelerations of Haupapa/Tasman Glacier are accompanied by abundant seismicity. This seismicity reveals some of the glacial processes occurring at times of accelerated glacier sliding and those related directly to surficial water inputs.To study the processes occurring during rain-induced accelerations a network of seismic and geodetic sensors was deployed on the lower Haupapa/Tasman Glacier for four months in 2016. Seven categories of seismicity were defined during the study period. Glacier source processes were inferred for these categories based on their waveform characteristics, and each source was then compared to meteoric and geodetic data to discern spatial and temporal relationships. Of the seven categories of seismicity only the seismic events associated with crevasse opening were found to correlate with rain rate. Increased crevassing rate likely results from two factors: 1) increased extensional strain rates following the propagation of a subglacial cavitation front during transient accelerations and 2) hydrofracture due to the accumulation of rain in crevasses. Strain-driven crevassing is associated only with glacier acceleration, but crevasse opening via hydrofracture is inferred to occur independently of strain changes such that it is an active process at any point following heavy rainfall. Basal seismicity was not observed to respond to changes in glacier velocity or inferred subglacial water pressure, although this may be due to limitations in the seismic event detection technique.</p>

Seismic and Geodetic Observations of Accelerated Sliding at Haupapa/Tasman Glacier, New Zealand

<p>Rain-induced accelerations of Haupapa/Tasman Glacier are accompanied by abundant seismicity. This seismicity reveals some of the glacial processes occurring at times of accelerated glacier sliding and those related directly to surficial water inputs.To study the processes occurring during rain-induced accelerations a network of seismic and geodetic sensors was deployed on the lower Haupapa/Tasman Glacier for four months in 2016. Seven categories of seismicity were defined during the study period. Glacier source processes were inferred for these categories based on their waveform characteristics, and each source was then compared to meteoric and geodetic data to discern spatial and temporal relationships. Of the seven categories of seismicity only the seismic events associated with crevasse opening were found to correlate with rain rate. Increased crevassing rate likely results from two factors: 1) increased extensional strain rates following the propagation of a subglacial cavitation front during transient accelerations and 2) hydrofracture due to the accumulation of rain in crevasses. Strain-driven crevassing is associated only with glacier acceleration, but crevasse opening via hydrofracture is inferred to occur independently of strain changes such that it is an active process at any point following heavy rainfall. Basal seismicity was not observed to respond to changes in glacier velocity or inferred subglacial water pressure, although this may be due to limitations in the seismic event detection technique.</p>

THE RESIZING OF THE MOST POWERFUL ITALIAN INSTRUMENTAL EARTHQUAKE (SEPTEMBER 8, 1905, CALABRIA REGION, SOUTHERN ITALY)

The 8 September 1905 Calabria earthquake is the seismic event for which the Italian Seismic Catalogue shows the highest instrumental magnitude of the whole dataset. However, the reported Ms=7.47 was calculated over only two stations, and leaves room for a revision. In this work I provide a new estimate of the surface-wave magnitude of the earthquake calculated over sixteen individual values of magnitude from seven different stations. The new estimate is Ms=7.06±0.13, a value that is consistently lined up with other estimates provided by means of macroseismic or geological evidence. The novel estimate is stable despite alternative epicentral locations and different depths proposed for this event by several investigators. The net variation of almost half a unit magnitude implies a resizing of the seismogenic source of the event in the frame of the seismotectonics of the region, and highlights the strong need for a systematic revision of the instrumental magnitude estimates for several ‘historical’ earthquakes that occurred at the dawning of the instrumental seismology.