Seismicity in the Tsengwen reservoir area, Taiwan

1979 ◽  
Vol 69 (6) ◽  
pp. 1783-1796
Author(s):  
Francis T. Wu ◽  
Y. H. Yeh ◽  
Y. B. Tsai
Keyword(s):  
Water Level ◽  
Earthquake Swarm ◽  
Tectonic Stress ◽  
Thrust Fault ◽  
Time Study ◽  
Surrounding Area ◽  
Storage Volume ◽  
Loading Effects ◽  
Large Earthquakes ◽  
Stress Accumulation

abstract The Tsengwen reservoir, with a maximum depth of 128 m, and a storage volume of 708 × 106 m3, is located over an active thrust fault, the Chuko Fault. The Chuko Fault was evidently the causative fault of a magnitude 634 (Pasadena, MS earthquake in 1964. Filling of the reservoir started in April 1973 and water reached the designed level in September of that same year; since then, the water level has undergone yearly cycles with 40 to 50 m amplitude. An earthquake swarm occurred near the dam in December 1972, before the filling of the reservoir, and microearthquakes in the area have been monitored for various periods since that time. Before filling, there were some very shallow events, with depths less than 2.5 km, but these disappeared shortly after the water level rose to the maximum. The majority of hypocenters after reservoir loading lie in a layer between depths of 2.5 and 8 km; the seismicity under the reservoir is noticeably lower than that in the surrounding area. There is no obvious correlation of seismicity with water level, based on available data. The seismicity in the Tsengwen area can be described as a response of the over-pressured and fractured sedimentary strata to the tectonic stress accumulation, modified by the loading effects of the reservoir. A ts/tp versus time study revealed anomalies, but these are not precursory to large earthquakes, as the duration of the anomalies would imply.

Present-day tectonic stress regime in Egypt and surrounding area based on inversion of earthquake focal mechanisms

2013 ◽  
Vol 81 ◽  
pp. 1-15 ◽  
Author(s):  
H.M. Hussein ◽  
K.M. Abou Elenean ◽  
I.A. Marzouk ◽  
I.M. Korrat ◽  
I.F. Abu El-Nader ◽  
...  
Keyword(s):  
Tectonic Stress ◽  
Focal Mechanisms ◽  
Surrounding Area ◽  
Stress Regime ◽  
Earthquake Focal Mechanisms

scholarly journals Structure-controlled asperities of the 1920 Haiyuan M8.5 and 1927 Gulang M8 earthquakes, NE Tibet, China, revealed by high-resolution seismic tomography

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Quan Sun ◽  
Shunping Pei ◽  
Zhongxiong Cui ◽  
Yongshun John Chen ◽  
Yanbing Liu ◽  
...  
Keyword(s):  
High Resolution ◽  
Seismic Tomography ◽  
High Velocity ◽  
Three Dimensional ◽  
Large Earthquake ◽  
Velocity Model ◽  
Tectonic Stress ◽  
Double Difference ◽  
Source Regions ◽  
Large Earthquakes

AbstractDetailed crustal structure of large earthquake source regions is of great significance for understanding the earthquake generation mechanism. Numerous large earthquakes have occurred in the NE Tibetan Plateau, including the 1920 Haiyuan M8.5 and 1927 Gulang M8 earthquakes. In this paper, we obtained a high-resolution three-dimensional crustal velocity model around the source regions of these two large earthquakes using an improved double-difference seismic tomography method. High-velocity anomalies encompassing the seismogenic faults are observed to extend to depths of 15 km, suggesting the asperity (high-velocity area) plays an important role in the preparation process of large earthquakes. Asperities are strong in mechanical strength and could accumulate tectonic stress more easily in long frictional locking periods, large earthquakes are therefore prone to generate in these areas. If the close relationship between the aperity and high-velocity bodies is valid for most of the large earthquakes, it can be used to predict potential large earthquakes and estimate the seismogenic capability of faults in light of structure studies.

Increasing critical sensitivity of the Load/Unload Response Ratio before large earthquakes with identified stress accumulation pattern

2006 ◽  
Vol 428 (1-4) ◽  
pp. 87-94 ◽  
Author(s):  
Huai-zhong Yu ◽  
Zheng-kang Shen ◽  
Yong-ge Wan ◽  
Qing-yong Zhu ◽  
Xiang-chu Yin
Keyword(s):  
Response Ratio ◽  
Accumulation Pattern ◽  
Large Earthquakes ◽  
Stress Accumulation

scholarly journals Tectonic stress regime in the 2003–2004 and 2012–2015 earthquake swarms in the Ubaye Valley, French Alps

2018 ◽  
Vol 175 (6) ◽  
pp. 1997-2008 ◽  
Author(s):  
Lucia Fojtíková ◽  
Václav Vavryčuk
Keyword(s):  
Seismic Activity ◽  
Joint Inversion ◽  
Earthquake Swarm ◽  
Active Faults ◽  
Tectonic Stress ◽  
Geological Mapping ◽  
Earthquake Swarms ◽  
Stress Regime ◽  
French Alps ◽  
Principal Axes

Abstract We study two earthquake swarms that occurred in the Ubaye Valley, French Alps within the past decade: the 2003–2004 earthquake swarm with the strongest shock of magnitude ML = 2.7, and the 2012–2015 earthquake swarm with the strongest shock of magnitude ML = 4.8. The 2003–2004 seismic activity clustered along a 9-km-long rupture zone at depth between 3 and 8 km. The 2012–2015 activity occurred a few kilometres to the northwest from the previous one. We applied the iterative joint inversion for stress and fault orientations developed by Vavryčuk (2014) to focal mechanisms of 74 events of the 2003–2004 swarm and of 13 strongest events of the 2012–2015 swarm. The retrieved stress regime is consistent for both seismic activities. The σ 3 principal axis is nearly horizontal with azimuth of ~ 103°. The σ 1 and σ 2 principal axes are inclined and their stress magnitudes are similar. The active faults are optimally oriented for shear faulting with respect to tectonic stress and differ from major fault systems known from geological mapping in the region. The estimated low value of friction coefficient at the faults 0.2–0.3 supports an idea of seismic activity triggered or strongly affected by presence of fluids.

scholarly journals Connection of large earthquakes occurring moment with the movement of the Sun and the Moon and with the Earth crust tectonic stress character

2010 ◽  
Vol 10 (7) ◽  
pp. 1629-1633 ◽  
Author(s):  
M. K. Kachakhidze ◽  
R. Kiladze ◽  
N. Kachakhidze ◽  
V. Kukhianidze ◽  
G. Ramishvili
Keyword(s):  
Tectonic Stress ◽  
Point Of View ◽  
The Sun ◽  
Compression Stress ◽  
The Moon ◽  
Caucasus Region ◽  
The Earth ◽  
Triggering Factor ◽  
Exogenous Factors ◽  
Large Earthquakes

Abstract. It is acceptable that earthquakes certain exogenous (cosmic) triggering factors may exist in every seismoactive (s/a) region and in Caucasus among them. They have to correct earthquake occurring moment or play the triggering role in case when the region is at the limit of the critical value of the geological medium of course. Our aim is to reveal some exogenous factors possible to initiate earthquakes, on example of Caucasus s/a region, taking into account that the region is very complex by the point of view of the tectonic stress distribution. The compression stress directed from North to South (and vice versa) and the spread stress directed from East to West (and vice versa) are the main stresses acted in Caucasus region. No doubt that action of the smallest external stress may "work" as earthquakes triggering factor. In the presented work the Moon and the Sun perturbations are revealed as initiative agents of earthquakes when the directions of corresponding exogenous forces coincide with the directions of the compression stress or the spreading tectonic stress in the region.

Coseismic water-level changes in a well induced by teleseismic waves from three large earthquakes

2015 ◽  
Vol 651-652 ◽  
pp. 232-241 ◽  
Author(s):  
Yan Zhang ◽  
Li-Yun Fu ◽  
Fuqiong Huang ◽  
Xuezhong Chen
Keyword(s):  
Water Level ◽  
Water Level Changes ◽  
Teleseismic Waves ◽  
Large Earthquakes

Trench investigations through the trace of the 1980 El Asnam thrust fault: Evidence for paleoseismicity

1988 ◽  
Vol 78 (2) ◽  
pp. 979-999
Author(s):  
M. Meghraoui ◽  
H. Philip ◽  
F. Albarede ◽  
A. Cisternas
Keyword(s):  
Late Holocene ◽  
Slip Rate ◽  
Thrust Fault ◽  
Recurrence Time ◽  
Normal Faults ◽  
Tectonic Event ◽  
Vertical Movements ◽  
Radiocarbon Dates ◽  
Flood Deposits ◽  
Large Earthquakes

Abstract During the EI Asnam earthquake of 10 October 1980 (Ms = 7.3), a clear active thrust fault with left-lateral offset was observed. Three trenches have been excavated across this fault in order to determine slip rate and recurrence intervals between large earthquakes, and thus reconstruct its past activity. Exposure I was excavated in the flood area created in 1980 by a pressure ridge across the Cheliff and Fodda Rivers. Six flood deposits (silty-sandy and muddy horizons) alternating with paleosoils appear in this exposure; they are affected by normal faults associated with the main thrust fault. Assuming that every flood deposit results from a tectonic event of magnitude greater than 7, we can correlate previous flood deposits with these events. Exposures II and III display thrust faults displacing different paleosoils. We propose a sequence of reconstructions based on the thickness of the various deposits and the dip-slip of each tectonic event. The Late Holocene slip rate is 0.65 mm/yr for the dip-slip and 0.46 mm/yr for each of the horizontal and the vertical movements. Radiocarbon dates of coseismic movements indicate a rather irregular seismic activity during the past 7000 yr. Two sequences of large earthquakes around 4000 yr B.P. and around the modern age are separated with a period of quiescence. The average Late Holocene recurrence interval of large earthquakes is 1061 yr; however, during the active faulting episodes, the recurrence time varies from approximately 300 to 500 yr.

Sign in / Sign up

Export Citation Format

Share Document