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1.
L.I. Morozova 《Russian Geology and Geophysics》2012,53(4):416-423
We consider different kinds of linear cloud anomalies appearing in satellite images over active crustal faults. The spatiotemporal relationship between earthquakes and cloud anomalies was studied by statistical methods. It has been shown that these cloud anomalies in the atmosphere can be used for short-term prediction of the earthquake time and region. Also, we consider the earthquake-related evolution of the giant thunderstorm cloud near the epicenter before the earthquake. 相似文献
2.
Static stress changes caused by megathrust slip of the 2011 Mw 9.0 Tohoku-Oki earthquake considerably affected the seismicity patterns in inland areas, resulting in the occurrence of numerous earthquakes along several active faults in Japan. On June 30, 2011, the Mj 5.4 central Nagano earthquake occurred at a shallow depth of 5 km, indicating the reactivation of the Gofukuji fault in Central Japan. This study was undertaken to elucidate spatial and temporal changes of 3He/4He ratios around a source region before and after an inland earthquake using both existing and new and helium isotope data from hot spring and drinking water wells. Gas samples near the Gofukuji fault and its surrounding active faults are characterized by an increase in postseismic 3He/4He ratios. In contrast, the postseismic ratios decreased by up to about 30% away from the mainshock epicenter. Episodic faulting could either release stored crustal (radiogenic) helium from host rocks, or enhance the transfer of mantle volatiles through permeable fault zones, such that subsequent fluid flow near to the source region could then explain the spatio-temporal variations in 3He/4He ratios. 相似文献
3.
利用美国国家和海洋大气管理局(NOAA)的大气温度数据, 分析陆地地震和海洋地震震前震中上空的大气温度变化, 研究其作为地震短临前兆的可能性.地震样本包括2014年2月12日于田Ms7.3地震、2008年5月12日汶川Ms8.0地震、2011年3月11日日本Ms9.0地震、2014年4月1日智利Ms8.1海洋地震、2013年3月27日台湾南投县Ms6.1地震和2014年5月30日云南盈江Ms6.1地震.结果表明: (1)震前, 震中位置300~1 000 hPa大气温度有较为一致的变化趋势; (2)200 hPa与400 hPa处(根据不同地点可选择其他, 诸如350 hPa、300 hPa等高度数据)温度折线图在震前趋近或者相交, 出现类似蝴蝶翅膀的"蝴蝶形"特殊曲线形状; (3)200 hPa与400 hPa温度差等值线图在(震前数月、数周或数天不等)震中附近区域的数值减小, 温度差等值线图的塌陷最低点对应震中位置.以上规律有望应用于地震短临预测的时间与震中的确定. 相似文献
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Water level fluctuations in twenty-one observation wells have been monitored for the last 10 years around the seismically active Koyna–Warna region, western India where earthquakes continue to occur even after four decades of the initiation of the seismic activity in the region. Fourteen of the observation wells act as volume strain meters as their water levels show earth tidal signals. Our analysis suggests three types of response of the well water levels to seismo-tectonic effects, i) one to local earthquakes, ii) to regional and teleseismic events, and iii) to local fluctuations in rock strain on regional scale. We observed five cases of co-seismic step-like well water level changes, of the order of few centimeters in amplitude, related to earthquakes in the magnitude range 4.3 ≤ M ≤ 5.2. All these earthquakes occurred within the network of wells drilled for the study and within 25 km distance of the recording wells. In three cases, drop in well levels preceded co-seismic step-like increases, which may be of premonitory nature. The second type of response is observed to be due to the passing of seismic waves from regional and teleseismic earthquakes like the M 7.7 Bhuj event on January 26, 2001 and the M 9.3 December 26, 2004 Sumatra earthquake. The third type is a well level anomaly of centimeter amplitude coherently occurring in several wells. The anomalies are similar in shape and last for several hours to days.From our studies we conclude that the wells in the network appear to respond to regional strain variations and transient changes due to distant earthquakes. The two factors which are important to co-seismic steps due to local earthquakes are the magnitude and epicentral distance. From the limited number of events we found that all local earthquakes exceeding M ≥ 4.3 have produced co-seismic changes. No such changes were observed for earthquakes below this magnitude threshold. 相似文献
6.
This article is devoted to evaluating destructive earthquakes (magnitude >6) of Iran and determining properties of their source parameters. First of all, a database of documented earthquakes has been prepared via reliable references and causative faults of each event have been determined. Then, geometric parameters of each fault have been presented completely. Critical parameters such as Maximum Credible Rupture, MCR, and Maximum Credible Earthquake, MCE, have been compiled based on the geometrical parameters of the earthquake faults. The calculated parameters have been compared to the maximum earthquake and the surface rupture which have been recorded for the earthquake faults. Also, the distance between the epicenter of documented earthquake events and their causative faults has been calculated (the distance was less than 20 km for 90% of the data). Then, the distance between destructive earthquakes (with the magnitude more than 6) and the nearest active fault has been calculated. If the estimated distance is less than 20 km and the mechanism of the active fault and the event are reported the same, the active fault will be introduced as a probable causative fault of that earthquake. In the process, all of the available geological, tectonic, seismotectonic maps, aerial geophysical data as well as remote sensing images have been evaluated. Based on the quality and importance of earthquake data, the events have been classified into three categories: (1) the earthquakes which have their causative faults documented, (2) the events with magnitude higher than 7, and (3) the events with the magnitude between 6 and 7. For each category, related maps and tables have been compiled and presented. Some important faults and events have been also described throughout the paper. As mentioned in this paper, these faults are likely to be in high seismic regions with potential for large-magnitude events as they are long, deep and bound sectors of the margins characterized by different deformation and coupling rates on the plate interface. 相似文献
7.
大地震发生的网络性质——兼论有关地震预测的争论 总被引：22，自引：0，他引：22
现有地震形成机制的假说大多是仅考虑震源及其邻近地区的事实依据。文中提出 :大地震的形成机制具有网络特性 ,把大地震看成是多层次网络的节点。一个地震的发生是多种动力 (包括天文因素 )作用的结果。地震形成机制的网络假说能较好地综合已有概念 ,解释地震预测研究中发现许多新现象。从网络假说看近年来“地震能否预测”的争论可有许多新启示。如果应用网络假说 ,至少一部分地震应是可以预测的。 相似文献
8.
2013年8月28日、31日, 云南迪庆藏族自治州香格里拉县、德钦县、四川省甘孜藏族自治州得荣县交界地区连续发生5.1级、5.9级地震.为了查明此次地震的影响破坏程度, 进行了地震现场建筑物震害考察并对震中附近断裂进行了野外构造地质剖面调查.两次地震在短时间内并在相近位置连续发生, 造成了此次云南香格里拉、德钦-四川得荣交界地震比以往同级地震的破坏程度要高, 地震烈度最高为Ⅷ级, 有感范围大, 5.9级地震宏观震中大致处在整个灾区破坏最严重的奔子栏镇争古村一带(28.20°N, 99.36°E), 距离地震微观震中约5.1km.等震线沿德钦-中甸断裂呈北西向分布, 近似为椭球状, 结合此次地震震中附近区域现场断裂调查、震源机制解数据以及地震余震空间分布特征, 初步推断此次地震的发震构造为德钦-中甸断层, 其主要表现为一次以正断为主兼有左旋走滑错动的地震事件. 相似文献
9.
Satellite monitoring of anomalous effects in the ionosphere related to the great Wenchuan earthquake of May 12, 2008 总被引：1，自引：0，他引：1
In this paper, we present an investigation into plasma density disturbances and electric field perturbations associated with
China, Sichuan, Wenchuan earthquake of magnitude M = 7.9 that occurred on May 12, 2008, at 06:28:01 UTC. The DEMETER (Detection
of Electromagnetic Emissions Transmitted from Earthquake Regions) satellite was launched on June 29, 2004. The orbit of DEMETER
is polar, circular with an altitude of 710 km and its main scientific objective is the study of ionospheric perturbations
linked to seismic activity. For satellite orbits near the epicenter region, some ionospheric effects are investigated, which
can be considered as possible earthquake precursors. The paper discusses anomalous effects in the ionosphere associated with
the Wenchuan earthquake, which cannot be explained by factors of solar-magnetospheric origin. For satellite orbits eight to
four days before the main shock, fluctuations in ion density and increase in horizontal and vertical components of electric
field are observed near the epicenter. Post-effect is observed too. The observations suggest a coupling between the lithosphere-atmosphere-ionosphere
and can be associated with the earthquake growing processes in the lithosphere and troposphere zones above the source. The
results of ionospheric anomalous effects are presented and discussed. The results obtained are important because they are
observed very near to epicenter. 相似文献
10.
The Mw 9.0 Tohoku-Oki earthquake that occurred off the Pacific coast of Japan on March 11, 2011, was followed by thousands of aftershocks, both near the plate interface and in the crust of inland eastern Japan. In this paper, we report on two large, shallow crustal earthquakes that occurred near the Ibaraki-Fukushima prefecture border, where the background seismicity was low prior to the 2011 Tohoku-Oki earthquake. Using densely spaced geodetic observations (GPS and InSAR datasets), we found that two large aftershocks in the Iwaki and Kita-Ibarake regions (hereafter referred to as the Iwaki earthquake and the Kita-Ibarake earthquake) produced 2.1 m and 0.44 m of motion in the line-of-sight (LOS), respectively. The azimuth-offset method was used to obtain the preliminary location of the fault traces. The InSAR-based maximum offset and trace of the faults that produced the Iwaki earthquake are consistent with field observations. The fault location and geometry of these two earthquakes are constrained by a rectangular dislocation model in a multilayered elastic half-space, which indicates that the maximum slips for the two earthquakes are 3.28 m and 0.98 m, respectively. The Coulomb stress changes were calculated for the faults following the 2011 Mw 9.0 Tohoku-Oki earthquake based on the modeled slip along the fault planes. The resulting Coulomb stress changes indicate that the stresses on the faults increased by up to 1.1 MPa and 0.7 MPa in the Iwaki and Kita-Ibarake regions, respectively, suggesting that the Tohoku-Oki earthquake triggered the two aftershocks, supporting the results of seismic tomography. 相似文献
11.
We present data analysis of multi-electrode measurements performed in the tectonosphere-atmosphere interface at Pizzoli and Chieti observatories located at distances 30–50 km and 90–110 km from earthquakes epicenters in Central Italy accordingly. Time intervals include 30 days of observations before earthquakes occurred on 24 August (M6.2), on 26 October (M6.1) and on 30 October, 2016 (M6.6). The recorded signals are two component time series with time step 1 s representing alternative and direct electromotive force components. Alternative electromotive force component in frequency band of 0.01 Hz to 4000 Hz is being recorded. Basic study has been carried out since 1989 at Kamchatka peninsula and since 2012 across Eurasia. The observation of nonstationary electric processes illustrates the nucleation of seismogenetic activity. We propose the hypothesis that nonstationary (sudden, abrupt in amplitude) electrical signals illustrate the proton permeability of rocks laying underneath the measuring sensor including a unique phenomenon of anomalous spontaneous deformation due to combination of proton environment and polymorphic transformation in condensed media. One of the interesting results is distinguishing the main zone of major earthquake nucleation which is corresponding as the earthquakes epicenters in Central Italy with M > 6. We suggest that by covering the northern, central and southern parts of Italy with a network of multi-electrode observatories near fault lines, towns and villages could pinpoint the possible coordinates of earthquake epicenter in a 30 day time window. The Chieti and Pizzoli observatories can form the basis of an extended network. 相似文献
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Naoki Uchida Satoshi Yui Satoshi Miura Toru Matsuzawa Akira Hasegawa Yoshinobu Motoya Minoru Kasahara 《Gondwana Research》2009,16(3-4):527-533
We analyzed small repeating earthquakes recorded over a 13-year period and GPS data recorded over an 8-month period to estimate interplate quasi-static slip associated with the 2003 Tokachi-oki earthquake (M8.0) and the 2004 off-Kushiro earthquake (M7.1). The repeating-earthquake analysis revealed that the slip rate near the source region of the Tokachi-oki earthquake was relatively low (< 5 cm/year) prior to the earthquake; however, in the last 3 years leading up to the event, a minor acceleration in slip occurred upon the deeper extension of the coseismic slip area of the earthquake. Repeating-earthquake and GPS data indicate that large amounts of afterslip occurred around the rupture area following the earthquake; the afterslip mainly propagated to the east of the coseismic slip area. We also infer that the occurrence of the 2004 off-Kushiro earthquake, located about 100 km northeast of the epicenter of the Tokachi-oki earthquake, was advanced by the afterslip associated with the Tokachi-oki earthquake. 相似文献
14.
通过分析中国航空工业总公司625研究所地电场监测站30多年监测的原始资料, 提取了其中8组数据, 包括4组地电场中的长期异常信号和4组对应震级Ms6.0以上的地震震前短临异常信号.发现这些异常信号有以下特征: 地电场中的长期监测图中包括了许多不同大小、距离远近地震的孕震信息, 其中近区大震会主控一条或多条曲线的走势, 远大、近小的地震会造成曲线时上时下的振荡; 从4组地电场短临信号监测图中发现震前地电场异常总体表现为下降(上升)—折返—回跳—发震的模式, 说明地电场异常变化形态具有相似性和重复性, 证明地电场观测确实能监测到震前异常.发现适合该监测站预测发震时间的新方法: 根据折返天数与回跳天数大致相等, 即回跳日期加上折返天数为发震日期, 证明地电场短临预测方法具有一定的实用性. 相似文献
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Usage of an early warning and information system Web-site for real-time seismicity in Iceland 总被引：1，自引：1，他引：0
Iceland has been subjected to destructive earthquakes and volcanic eruptions throughout history. Such events are often preceded
by changes in earthquake activity over varying timescales. Although most seismicity is confined to micro-earthquakes, large
earthquakes have occurred within populated regions. Following the most recent hazardous earthquakes in 2000, the Icelandic
Meteorological Office (IMO) developed an early warning and information system (EWIS) Web-site for viewing near-real-time seismicity
in Iceland. Here we assess Web-site usage data in relation to earthquake activity, as recorded by the South Iceland Lowland
(SIL) seismic network. Between March 2005 and May 2006 the SIL seismic network recorded 12,583 earthquakes. During this period,
the EWIS Web-site logged a daily median of 91 visits. The largest onshore event (M
L 4.2) struck 20 km from Reykjavík on 06 March 2006 and was followed by an immediate, upsurge in usage resulting in a total
of 1,173 unique visits to the Web-site. The greatest cluster of large (≥M
L 3) events occurred 300 km offshore from Reykjavík in May 2005. Within this swarm, 9 earthquakes ≥M
L 3 were detected on 11 May 2005, resulting in the release of a media bulletin by IMO. During the swarm, and following the
media bulletin, the EWIS Web-site logged 1,234 unique visits gradually throughout the day. In summary, the data reveal a spatial
and temporal relationship between Web-site usage and earthquake activity. The EWIS Web-site is accessed immediately after
the occurrence of a local earthquake, whereas distant, unfelt earthquakes generate gradual interest prompted by media bulletins
and, possibly, other contributing factors. We conclude that the Internet is a useful tool for displaying seismic information
in near-real-time, which has the capacity to help increase public awareness of natural hazards. 相似文献
17.
Takashi Furumura Shunsuke Takemura Shinako Noguchi Teito Takemoto Takuto Maeda Kazuhisa Iwai Simanchal Padhy 《Landslides》2011,8(3):333-338
The dense recordings of the K-NET and KiK-net nationwide strong motion network of 1,189 accelerometers show clearly the radiation
and propagation properties of the strong ground motions associated with the 2011 off-the-Pacific Coast-of-Tohoku, Japan (Mw = 9.0)
earthquake. The snapshots of seismic wave propagation reveal strong ground motions from this earthquake that originate from
three large slips; the first two slips occurred over the plate interface of off-Miyagi at the southwest and the east of the
hypocenter, and the third one just beneath the northern end of Ibaraki over the plate interface or in the crust. Such multiple
shocks of this event caused large accelerations (maximum 1–2 G) and prolonged ground shaking lasting several minutes with
dominant high-frequency (T < 1 s) signals over the entire area of northern Japan. On the other hand, ground motions of relatively longer–period band
(T = 1–2 s), which caused significant damage to wooden-frame houses, were about 1/2–1/3 of those observed near the source area
of the destructive 1995 Kobe, Japan (M = 7.3) earthquake. Also, the long-period (T = 6–8 s) ground motion in the Kanto (Tokyo) sedimentary basin was at an almost comparable level of those observed during
the recent Mw = 7 inland earthquakes, but not as large as that from the former M = 8 earthquakes. Therefore, the impact of
the strong ground motion from the present M = 9 earthquake was not as large as expected from the previously M = 7–8 earthquakes
and caused strong motion damage only to short-scale construction and according to instruments inside the buildings, both have
a shorter (T < 1 s) natural period. 相似文献
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Chen Kuang-Jung Chiu Bonbbon Wang Jee-Shiang Lee Cheng-Yu Lin Cheng-Horng Chao Kevin 《Natural Hazards》2011,58(3):1233-1252
A strong earthquake with a magnitude of 7.6 (M
L
= 7.3) occurred on September 21, 1999, in central Taiwan. In order to discern any potential precursors before this earthquake,
geomagnetic data at Lunping (LNP), Taiwan, Geomagnetic Observatory situated 100 km from the epicenter are examined using two
methods, i.e., the traditional induction arrows and complex demodulation. Our results show that the remarkable temporal variation
of real induction arrows appear to be strong prior to the great earthquake over the previous 24 months. After the great earthquake,
the magnitudes of induction arrows decreased to the normal (mean of 8 years) levels. In other words, the direction of real
induction arrows of the periods 30 and 20 min rotated 85° and 40° anticlockwise, respectively, before the Chi-Chi earthquake
and returned to mean direction of last 10 years after the earthquake. A horizontal source field model using the finite difference
method for 3-D shows that the variation of the real induction arrows might be ascribed to the conductivity variation body,
which is 5 km buried at the epicenter area of the Chi-Chi earthquake, changing its conductivity from 0.002S/m to 0.06 S/m.
The ratios of modulus (demodulated by using the complex demodulation method) over a period 12, and 8 h relative to the period
of 24 h reveal a remarkable change that appeared 4–5 months prior to this strong earthquake. They increased gradually from
the beginning of 1999 to August 1999 and decreased again to a (8 years) mean level after the strong earthquake occurrence.
We consider that the variation of the induction arrow might be ascribed to the conductivity anomaly, which is buried 5 km
at the south-east side of LNP with a conductivity change of 0.06 S/m. We propose that this elevation might be related to the
preparation process of the great earthquake. 相似文献
20.
本文根据莆田地震台近几年来电磁波观资料的分析 ,震例研究结果表明 ,电磁辐射信号常在震前存在着起始异常 -主异常 -衰减异常 -平静 -临震异常、在平静时地震的特征。本文对闽台地区几次中强地震电磁观测和研究以及对地震的短临预报起到了一定推动作用。 相似文献