Abstract. Analysis of the 2007 M5.4 Alum Rock earthquake near San José California showed that magnetic pulsations were present in large numbers and with significant amplitudes during the 2 week period leading up the event. These pulsations were 1-30 s in duration, had unusual polarities (many with only positive or only negative polarities versus both polarities), and were different than other pulsations observed over 2 years of data in that the pulse sequence was sustained over a 2 week period prior to the quake, and then disappeared shortly after the quake. A search for the underlying physics process that might explain these pulses was was undertaken, and one theory (Freund, 2002) demonstrated that charge carriers were released when various types of rocks were stressed in a laboratory environment. It was also significant that the observed charge carrier generation was transient, and resulted in pulsating current patterns. In an attempt to determine if this phenomenon occurred outside of the laboratory environment, the authors scaled up the physics experiment from a relatively small rock sample in a dry laboratory setting, to a large 7 metric tonne boulder comprised of Yosemite granite. This boulder was located in a natural, humid (above ground) setting at Bass Lake, Ca. The boulder was instrumented with two Zonge Engineering, Model ANT4 induction type magnetometers, two Trifield Air Ion Counters, a surface charge detector, a geophone, a Bruker Model EM27 Fourier Transform Infra Red (FTIR) spectrometer with Sterling cycle cooler, and various temperature sensors. The boulder was stressed over about 8 h using expanding concrete (Bustar tm ), until it fractured into three major pieces. The recorded data showed surface charge build up, magnetic pulsations, impulsive air conductivity changes, and acoustical cues starting about 5 h before the boulder actually Correspondence to: T. Bleier (tbleier@quakefinder.com) broke. These magnetic and air conductivity pulse signatures resembled both the laboratory rock stressing results and the 30 October 2007 M5.4 Alum Rock earthquake field data.The second part of this paper examined other California earthquakes, prior to the Alum Rock earthquake, to see if magnetic pulsations were also present prior to those events. A search for field examples of medium earthquakes was performed to identify earthquakes where functioning magnetometers were present within 20 km, the expected detection range of the magnetometers. Two earthquakes identified in the search included the 12 August 1998 M5.1 San Juan Bautista (Hollister Ca.) earthquake and the 28 September 2004 M6.0 Parkfield Ca. earthquake. Both of these data sets were recorded using EMI Corp. Model BF4 induction magnetometers, installed in equipment owned and operated by UC Berkeley. Unfortunately, no air conductivity or IR data were available for these earthquake examples. This new analysis of old data used the raw time series data (40 samples per s), and examined the data for short duration pulsations that exceeded the normal backgro...
Abstract. The QuakeFinder network of magnetometers has recorded geomagnetic field activity in California since 2000. Established as an effort to follow up observations of ULF activity reported from before and after the M = 7.1 Loma Prieta earthquake in 1989 by Stanford University, the QuakeFinder network has over 50 sites, fifteen of which are high-resolution QF1005 and QF1007 systems. Pairs of highresolution sites have also been installed in Peru and Taiwan.Increases in pulse activity preceding nearby seismic events are followed by decreases in activity afterwards in the three cases that are discussed here. In addition, longer term data is shown, revealing a rich signal structure not previously known in QuakeFinder data, or by many other authors who have reported on pre-seismic ULF phenomena. These pulses occur as separate ensembles, with demonstrable repeatability and uniqueness across a number of properties such as waveform, angle of arrival, amplitude, and duration. Yet they appear to arrive with exponentially distributed inter-arrival times, which indicates a Poisson process rather than a periodic, i.e., stationary process.These pulses were observed using three-axis induction coil magnetometers that are buried 1-2 m under the surface of the Earth. Our sites use a Nyquist frequency of 16 Hertz (25 Hertz for the new QF1007 units), and they record these pulses at amplitudes from 0.1 to 20 nano-Tesla with durations of 0.1 to 12 s. They are predominantly unipolar pulses, which may imply charge migration, and they are stronger in the two horizontal (north-south and east-west) channels than they are in the vertical channels. Pulses have been seen to occur in bursts lasting many hours. The pulses have large Correspondence to: J. C. Dunson (cdunson@quakefinder.com) amplitudes and study of the three-axis data shows that the amplitude ratios of the pulses taken from pairs of orthogonal coils is stable across the bursts, suggesting a similar source. This paper presents three instances of increases in pulse activity in the 30 days prior to an earthquake, which are each followed by steep declines after the event. The pulses are shown, methods of detecting the pulses and calculating their azimuths is developed and discussed, and then the paper is closed with a brief look at future work.
RESUMENLos bosque templados del sur de Chile y Argentina mantienen altos niveles de diversidad y endemicidad. A pesar de ello pocos son los estudios centrados en cuantifi car los patrones de diversidad de los taxa de mayor riqueza específi ca como los insectos en estos ecosistemas. Uno de los grupos menos estudiados a pesar de su alta diversidad es el de los insectos parasitoides. En este trabajo se analizan los patrones de riqueza y diversidad de uno de los grupos de parasitoides con mayor endemicidad, los pompílidos (Hymenoptera: Pompilidae). Se muestrearon utilizando trampas Malaïse, cuatro hábitats de bosque siempreverde costero en la provincia de Valdivia durante 21 fechas, obteniéndose 9 especies de pompílidos pertenecientes a 3 géneros. A pesar del bajo número de individuos, todas las especies colectadas son endémicas de las Subrregiones Chilena Central y Subantártica. ABSTRACTTemperate forests of south Chile and Argentina treasure high levels of diversity and endemicity. However, there are few studies that quantify diversity patterns of higher species richness taxa like insects in these ecosystems., One of the less studied groups in spite of their high diversity are insect parasitoids. In this study we analyzed richness and diversity patterns of one group of parasitoids with higher endemicity pompilids (Hymenoptera: Pompilidae). We sampled four evergreen coastal forest habitats using Malaïse traps in Valdivia province along 21 dates and we obtained a total of 9 pompilid species within 3 genera. Despite of the low number of species collected, all species collected are endemics of Central Chilean and Subantarctic Subregions.
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