Rupture process of the M L=4.1 earthquake in Huailai Basin on July 20, 1995

Abstract

On July 20, 1995, an earthquake of ML=4.1 occurred in Huailai basin, northwest of Beijing, with epicenter coordinates 40.326°N, 115.448°E and focal depth 5.5 km. Following the main shock, seismicity sharply increased in the basin. This earthquake sequence was recorded by Sino-European Cooperative Huailai Digital Seismograph Network (HDSN) and the hypocentres were precisely located. About 2 hours after the occurrence of the main shock, a smaller event of ML=2.0 took place at 40.323°N, 115.447°E with a focal depth of 5.0 km, which is very close to the main shock. Using the ML=2.0 earthquake as an empirical Green's function, a regularization method was applied to retrieve the far-field source-time function (STF) of the main shock. Considering the records of HDSN are the type of velocity, to depress high frequency noise, we removed instrument response from the records of the two events, then integrated them to get displacement seismogram before applying the regularization method. From the 5 field stations, P phases in vertical direction which mostly are about 0.5 s in length were used. The STFs obtained from each seismic phases are in good agreement, showing that the ML=4.1 earthquake consisted of two events. STFs from each station demonstrate an obvious "seismic Doppler effect". Assuming the nodal plane striking 37 ° and dipping 40 °, determined by using P wave first motion data and afiershock distribution, is the fault plane, through a trial and error method, the following results were drawn: Both of the events lasted about 0.1 s, the rupture length of the first one is 0.5 km, longer than the second one which is 0.3 km, and the rupture velocity of the first event is 5.0 km/s, larger than that of the second one which is about 3.0 km/s; the second event took place 0.06 s later than the first one; on the fault plane, the first event ruptured in the direction ?'=140 ° measured clockwise from the strike of the fault, while the second event ruptured at Y =80°, the initial point of the second one locates at ?" = -100 ° and 0.52 km from the beginning point of the first one. Using far-field ground displacement spectrum measurement method, the following source parameters about the ML=4.1 earthquake were also reached: the scalar earthquake moment is 3.3x 10 ~3 N.m, stress drop 4.6 MPa, rupture radius 0.16 km. ACTA SEISMOLOGICA SINICA Vol. 12 of the ML=4.1 earthquake. Key words: empirical Green's function Huailai basin rupture process source-time function

Teleseismic Receiver Function and Surface-Wave Study of Velocity Structure beneath the Yanqing-Huailai Basin Northwest of Beijing

“…Che et al (2001) suggest that the strength of the upper crust has been decreased by the action of hot fluids consistent with the small and moderate earthquake locations and the existence of hot springs in the region. Detailed modeling and moment tensor inversion for the Huailai M L event in 1995 (Xu et al, 1999(Xu et al, , 2001 led to a source depth estimate of 5.5 km again in the higher velocity layers of our model. Sun et al (1987) propose that the geothermal anomaly and tectonic extension are possibly related to the existence of the low-velocity layers.…”

“…An M L 4.1 earthquake occurred in the Yanqing-Huailai Basin on 20 July 1995, followed by approximately 450 aftershocks (Chen et al, 1998). Xu et al (1999Xu et al ( , 2001 and Chen et al (2005) have studied the rupture process and focal mechanism of this earthquake and the following earthquake sequence.…”

Современные Тенденции Устойчивого Развития Ягодоводства России (Смородина, Крыжовник): Сб. Науч. Трудов, Посвященный 110-Летию Со Дня Рожд. Доктора С.-Х. Наук, Заслуж. Деятеля Науки РСФСР К.Д. Сергеевой

“…По нашим [12,26] и литературным данным [3,28,31,33] отмечается тенденция быстрого увеличения активности окислительного фермента пероксидазы у устойчивых растений после внедрения патогена, противоположная тенденция складывается у восприимчивых растений. Повышение ферментативной активности связано с мобилизацией защитных реакций у растений в ответ на проникновение возбудителя.…”

Quantification of 3‐n‐butylphthalide in beagle plasma samples by supercritical fluid chromatography with triple quadruple mass spectrometry and its application to an oral bioavailability study

“…3-n-Butylphthalide (NBP) [(±)-3-butyl-1(3H)-isobenzofuranone] was firstly isolated from Chinese herbs, including Apium graveolens, Ligusticum sinensis, and Liqusticum Chuanxiong Hort [1][2][3], and has also been obtained by chemical synthesis [4,5]. NBP is currently used clinically as a preferred drug for the treatment of ischemic stroke by increasing regional cerebral blood flow and inhibiting the release of glutamate and 5-hydroxytryptamine [6,7]. In addition, recent research has demonstrated that NBP displays beneficial effects by attenuating amyloid-induced cell death in neuronal cultures [8], improving cognitive deficits and preventing neuronal cell death after focal cerebral ischemia in mice [9,10] Abbreviations: C max , peak serum concentration; LLOQ, lower limit of quantification; ME, matrix effect; MRM, multiple reaction monitoring; NBP, 3-n-butylphthalide; QC, quality control; sCO 2 , supercritical carbon dioxide; SFC, supercritical fluid chromatography; T max , the time to reach the peak concentration and protecting cardiomyocytes from ischemia/reperfusioninduced apoptosis [11].…”