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News Article | April 28, 2017

"We do not expect major damage after this event," Philippine Institute of Volcanology and Seismology chief Renato Solidum said on ABS-CBN television in Manila (AFP Photo/PEDRO PARDO) A 6.8-magnitude earthquake struck off the Philippines early Saturday, triggering a tsunami warning that was later lifted, Philippine and US authorities said. There were no immediate reports of casualties or damage from the quake, which shook the southern region of Mindanao just before dawn, Philippine officials said. It struck at a depth of 41 kilometres (25 miles) in Mindanao, more than 700 kilometres southeast of the capital Manila, at 4:23 am Saturday (2023 GMT Friday), the US Geological Service said. "We do not expect major damage after this event," Philippine Institute of Volcanology and Seismology chief Renato Solidum said on ABS-CBN television in Manila. The state-run institute gave a higher magnitude reading of 7.2. The epicentre was about 53 kilometres off Mindanao's south coast, it added. The Pacific Tsunami Warning Center initially advised that hazardous tsunami waves were possible off the coasts of the Philippines and Indonesia. Less than two hours later the US and Philippine authorities lifted the tsunami alert, saying the danger had passed. "There is no longer a tsunami threat from this earthquake," the US agency said. However Philippine authorities said they were checking potential local damage. The Philippines lies on the so-called Ring of Fire, a vast Pacific Ocean region where many of Earth's earthquakes and volcanic eruptions occur.

News Article | April 28, 2017

Members of Iraqi security forces inspect the site of car bomb attack in Baghdad, Iraq April 28, 2017. REUTERS/Khalid al Mousily MANILA (Reuters) - A strong earthquake measuring 7.2 struck off the coast of Mindanao island in the Philippines on Saturday, and the country's seismology agency advised people to stay away from coastal areas but expected no major damage. There were no immediate reports of destruction or casualties, but witnesses said the quake was very strong and shook the ground and walls. The Pacific Tsunami Warning Center said there was a risk big waves could spread 300 km (190 miles) away from the epicenter, reaching as far away as Indonesia. The Philippines Institute of Volcanology and Seismology (Philvolcs) said no tsunami warning was issued after a quake it had measured at 7.2. The U.S Geological Survey downgraded its own assessment of the magnitude to 6.8. The Philippines is on the geologically active Pacific Ring of Fire and experiences frequent earthquakes, particularly in the south, although there were several last month in Batangas on the main island of Luzon, felt also in the capital Manila. The earthquake was about 57 km (35 miles) southwest of Sarangani province, the southernmost part of Mindanao, the biggest island in the south of the archipelago nation. "It was so strong, you could hear the ground shaking for almost 10 seconds," Jenifer Bugtay, who works at a beach-front resort in Sarangani, said by telephone. "This is the strongest earthquake I have experienced," she said. "The wall looked like it would fall." Philvolcs head Renato Solidum said there was no need to evacuate the area. The quake was at sea, and deep, although the public had been advised to stay away from the coast in the south for the next few hours. Solidum said no major damage was anticipated. "Many of our southern cities are far from the epicenter so we are not expecting much damage," he told news channel ANC. "We have had some aftershocks, we expect that." Janet Bongolan, tourism officer at the Tuka Marine Park in Sarangani province, said people spilled out of their homes and into the streets during the earthquake, but most had returned and there was no sign of panic. "There's no news here that there will be a tsunami. But we are watching out for aftershocks. We are careful here," she said by telephone.

Agency: European Commission | Branch: FP7 | Program: CP-SICA | Phase: ENV.2007. | Award Amount: 5.03M | Year: 2008

In EU countries, volcanic risks assessment and management are tackled through scientific knowledge and monitoring, although there is still a need for integration between all risk management components. For international cooperation partner countries (ICPCs), the risk management depends on local situations but is often less favourable. Therefore, following UN International Strategy for Disaster Reduction recommendations and starting from shared existing knowledge and practices, the MIA-VITA project aims at developing tools and integrated cost effective methodologies to mitigate risks from various hazards on active volcanoes (prevention, crisis management and recovering). Such methodology will be designed for ICPCs contexts but will be helpful for European stakeholders to improve their experience in volcanic risk management. The project multidisciplinary team gathers civil defence agencies, scientific teams (earth sciences, social sciences, building, soil, agriculture, Information Technologies and telecommunications) and an IT private company. The scientific work will focus on: 1) risk assessment methodology based on a multi-risk approach developed at Mt Cameroon by one of the partners in cooperation with Cameroonian institutions 2) cost efficient monitoring tools designed for poorly monitored volcanoes (satellite & gas analysis & volcano-seismology) 3) improvement in terms of vulnerability assessment (people, buildings and biosphere) 4) socio-economic surveys to enhance community resilience 5) Integrated information system (data organisation and transfers, communications) taking advantage of GEONETCast initiative Results will be achieved with help from local scientists and stakeholders in Africa (Cameroon, Cape Verde), in Asia (Indonesia, Philippines) and will be validated on a European volcano (Montserrat). The objectives will be reached through sharing/transfer of know-how, through scientific and technological developments, and through dissemination/training.

Girina O.A.,Institute of Volcanology and Seismology
Journal of Volcanology and Geothermal Research | Year: 2013

Bezymianny Volcano is one of the most active volcanoes in the world. In 1955, for the first time in history, Bezymianny started to erupt and after six months produced a catastrophic eruption with a total volume of eruptive products of more than 3km3. Following explosive eruption, a lava dome began to grow in the resulting caldera. Lava dome growth continued intermittently for the next 57years and continues today. During this extended period of lava dome growth, 44 Vulcanian-type strong explosive eruptions occurred between 1965 and 2012. This paper presents a summary of activity at Bezymianny Volcano from 1956 to 2010 with a focus on descriptive details for each event. © 2013 Elsevier B.V.

Katsumata A.,Institute of Volcanology and Seismology
Journal of Geophysical Research: Solid Earth | Year: 2010

The crustal structure beneath the Japanese islands, including depth distributions of the Conrad and Moho discontinuities, was estimated using a tomographic inversion of regional body wave arrival times. Depth distributions of the bottom of the surface layer, the Conrad, and the Moho were modeled with two-dimensional B spline functions, while velocity distributions in layers were expressed by three-dimensional B spline functions. The depth of the discontinuities and the velocity in the layers were estimated simultaneously by the least squares method. The velocity structure was sequentially estimated from shallower parts to deeper parts to avoid correlation between them. This sequential analysis provided improved depth resolution. The deepest region of the Moho discontinuity was located in central Honshu, reaching about 40 km. The Moho discontinuity was generally deep in the central part of the islands, whereas it was relatively shallow in the Kanto, southwestern Chubu, and Chugoku districts in Honshu and in northern Kyushu. Some of the shallow Moho regions would be related to graben formation due to tensile tectonic stress since the Miocene. The results were compared with those of seismic refraction surveys and receiver function analyses, and it was found that the obtained model was consistent with many of these studies. © 2010 by the American Geophysical Union.

Hayashi Y.,Institute of Volcanology and Seismology
Earth, Planets and Space | Year: 2010

This study compares tsunami height data obtained by coastal tidal stations and offshore wave stations of the Nationwide Ocean Wave information network for Ports and HArbourS (NOWPHAS) with data obtained from real-time kinematic global positioning system (RTK-GPS) buoys. NOWPHAS wave stations and RTK-GPS buoys are typically installed off the coast-the former within several kilometers of the coast and the latter 2-20 km offshore. The ratio of initial tsunami height observed at a coastal tidal station to that observed at an offshore station was found to be approximately proportional to the fourth root of the ratio of the sea-bottom depths to the mean sea level at the respective offshore and coastal station. This approximation can also be applied to maximum tsunami amplitudes. The relationship derived in this paper will enable the initial tsunami height to be forecast by real-time applications using detected tsunami initial height from offshore stations, such as the sea-bottom pressure gauges of NOWPHAS stations and RTK-GPS buoys. Copyright © The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS).

Gusev A.A.,Institute of Volcanology and Seismology
Pure and Applied Geophysics | Year: 2013

Observed high-frequency (HF) radiation from earthquake faults exhibits specific properties that cannot be deduced or extrapolated from low-frequency fault behavior. In particular: (1) HF time functions look like random signals, with smooth mean spectrum and moderately heavy-tailed probability distribution function for amplitudes; (2) well-known directivity of low-frequency radiation related to rupture propagation is strongly reduced at HF, suggesting incoherent (delta-correlated) behavior of the HF radiator, and contradicting the usual picture of a rupture front as a regular, non-fractal moving line; (3) in the spectral domain, HF radiation occupies a certain specific band seen as a plateau on acceleration source spectra K(f) = f2 Ṁ0(f). The lower cutoff frequency fb of K(f) spectra is often located significantly higher than the common spectral corner frequency fc, or fa. In many cases, empirical fb(M0) trends are significantly slower as compared to the simple fbα M0 -1/3, testifying the lack of similarity in spectral shapes; (4) evidence is accumulating in support of the reality of the upper cutoff frequency of K(f): fault-controlled fmax, or fuf. However, its identification is often hampered by such problems as: (a) strong interference between fuf and site-controlled fmax; (b) possible location of fuf above the observable spectral range; and (c) substantial deviations of individual source spectra from the ideal spectral shape; (5) intrinsic structure of random-like HF radiation has been shown to bear significant self-similar (fractal) features. A HF signal can be represented as a product of a random HF "carrier signal" with constant mean square amplitude, and a positive modulation function, again random, that represents a signal envelope. It is this modulation function that shows approximately fractal behavior. This kind of behavior was revealed over a broad range of time scales, from 1 to 300 s from teleseismic data and from 0. 04 to 30 s from near-fault accelerogram data. To explain in a qualitative way many of these features, it is proposed that rupture propagation can be visualized as occurring, simultaneously, at two different space-time scales. At a macro-scale (i. e. at a low resolution view), one can safely believe in the reality of a singly connected rupture with a front as a smooth line, like a crack tip, that propagates in a locally unilateral way. At a micro-scale, the rupture front is tortuous and disjoint, and can be visualized as a multiply connected fractal "line" or polyline. It propagates, locally, in random directions, and is governed by stochastic regularities, including fractal time structure. The two scales and styles are separated by a certain characteristic time, of the order of (0. 07-0. 15) × rupture duration. The domain of fractal behavior spans a certain HF frequency range; its boundaries, related to the lower and upper fractal limits, are believed to be manifested as fb and fuf. © 2012 Springer Basel AG.

Belousov A.,Institute of Volcanology and Seismology | Belousova M.,Institute of Volcanology and Seismology | Nechayev A.,Moscow State University
Geology | Year: 2013

Several models have been proposed to explain periodic eruptions of geysers. In essence, the models all use two principally different types of geyser plumbing configurations, dealing with two different physical mechanisms. Here we present data on direct video observations of interior conduit systems for four erupting geysers in Geyser Valley, Kamchatka, Russia. The video footage reveals highly contorted water-filled conduits that periodically discharge voluminous parcels of steam bubbles during eruptions. These observations do not favor the models that use the most popular long vertical conduit type of plumbing, where eruptions are caused by sudden flashing of superheated water into steam. In contrast, our data fit the models using the less-explored type of plumbing, where pressurized steam gradually accumulates in an underground cavity (bubble trap) and periodically erupts through a water-filled, highly contorted conduit with the configuration of an inverted siphon. Hydrodynamic calculations show that such a plumbing configuration produces periodic eruptions when the volume of the bubble trap exceeds the volume of the conduit connecting it to the ground surface. Conduits of the studied geysers were developed from erosion by ascending geothermal water in landslide deposits; chaotic internal structures of the deposits facilitated the formation of conduit systems with highly contorted configurations of the bubble trap type. We suggest that geyser fields are rare on Earth because they require the combination of hydrothermal discharge and geological formations having specific mechanical properties and structures (that facilitate the generation of highly contorted conduits). © 2013 Geological Society of America.

Melnikov D.,Institute of Volcanology and Seismology | Volynets A.O.,Institute of Volcanology and Seismology
Journal of Volcanology and Geothermal Research | Year: 2015

We present a reconstruction of the chronological sequence of events that took place during the first days of the 2012-2013 Tolbachik fissure eruption using petrological data and remote sensing methods. We were forced to use this approach because bad weather conditions did not allow direct observations during the first two days of the eruption. We interpreted infrared images from the scanning radiometer VIIRS Suomi NPP and correlated the output with the results of the geochemical study, including comparison of the ash, deposited at the period from 27 to 29 November, with the samples of lava and bombs erupted from the Menyailov and Naboko vents. We argue that the compositional change observed in the eruption products (the decrease of SiO2 concentration and K2O/MgO ratio, increase of MgO concentration and Mg#) started approximately 24h after the eruption began. At this time the center of activity moved to the southern part of the fissure, where the Naboko group of vents was formed; therefore, this timeframe also characterizes the timing of the Naboko vent opening. The Naboko group of vents remained active until the end of eruption in September 2013. © 2015 Elsevier B.V.

Gusev A.A.,Institute of Volcanology and Seismology
Pure and Applied Geophysics | Year: 2011

To carry out a realistic simulation of earthquake strong ground motion for applied studies, one needs an earthquake fault/source simulator that can integrate most relevant features of observed earthquake ruptures. A procedure of this kind is proposed that creates a broadband kinematic source model. At lower frequencies, the source is described as propagating slip pulse with locally variable velocity. The final slip is assumed to be a two-dimensional (2D) random function. At higher frequencies, radiation from the same running strip is assumed to be random and incoherent in space. The model is discretized in space as a grid of point subsources with certain time histories. At lower frequencies, a realistic shape of source spectrum is generated implicitly by simulated kinematics of slip pulse propagation. At higher frequencies, the original approach is used to generate signals with spectra that plausibly approximate the prescribed smooth far-field source spectrum. This spectrum is set on the basis of the assumedly known regional empirical spectral scaling law, and subsource moment rate time histories are conditioned so as to fit this expected spectrum. For the random function that describes final slip over the fault area, lognormal probability distribution of amplitudes is assumed, on the basis of exploratory analysis of inverted slip distributions. Similarly, random functions that describe local slip rate time histories are assumed to have lognormal distribution of envelope amplitudes. In this way one can effectively emulate expressed "asperities" of final slip and occasional occurrence of large spikes on near-source accelerograms. A special procedure is proposed to simulate the spatial coherence of high-frequency fault motion. This approach permits the simulation of fault motion plausibly at high spatial resolution, fulfilling the prerequisite for simulation of strong motion in the vicinity of a fault. A particular realization (sample) of a source created in a simulation run depends on several random seeds, and also on a considerable number of parameters. Their values can be selected so as to take into account expected source features; they can also be perturbed to examine the source-related component of uncertainty of strong motion. The proposed approach to earthquake source specification is well adapted to the study of deterministic seismic hazard: it may be used for simulation of individual scenario events, or suites of such events, as well as for analysis of uncertainty for expected ground motion parameters from a particular class of events. Examples are given of application of the proposed approach to strong motion simulations and related uncertainty estimation. © 2010 Springer Basel AG.

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