Extreme hydrothermal conditions at an active plate-bounding fault.

Temperature and fluid pressure conditions control rock deformation and mineralization on geological faults, and hence the distribution of earthquakes. Typical intraplate continental crust has hydrostatic fluid pressure and a near-surface thermal gradient of 31 ± 15 degrees Celsius per kilometre. At temperatures above 300-450 degrees Celsius, usually found at depths greater than 10-15 kilometres, the intra-crystalline plasticity of quartz and feldspar relieves stress by aseismic creep and earthquakes are infrequent. Hydrothermal conditions control the stability of mineral phases and hence frictional-mechanical processes associated with earthquake rupture cycles, but there are few temperature and fluid pressure data from active plate-bounding faults. Here we report results from a borehole drilled into the upper part of the Alpine Fault, which is late in its cycle of stress accumulation and expected to rupture in a magnitude 8 earthquake in the coming decades. The borehole (depth 893 metres) revealed a pore fluid pressure gradient exceeding 9 ± 1 per cent above hydrostatic levels and an average geothermal gradient of 125 ± 55 degrees Celsius per kilometre within the hanging wall of the fault. These extreme hydrothermal conditions result from rapid fault movement, which transports rock and heat from depth, and topographically driven fluid movement that concentrates heat into valleys. Shear heating may occur within the fault but is not required to explain our observations. Our data and models show that highly anomalous fluid pressure and temperature gradients in the upper part of the seismogenic zone can be created by positive feedbacks between processes of fault slip, rock fracturing and alteration, and landscape development at plate-bounding faults.

[Experience with multiplex nested PCR and fluorescent antibody tests in the diagnosis of acute central nervous system infections with herpes simplex virus type 1 and 2]. / Tapasztalatok a heveny központi idegrendszeri fertozések herpes simplex vírus-1/2 diagnosztikájában a multiplex nested PCR- és a fluoreszcens jelzésu antitestválasz-vizsgálat kombinációjával.

UNLABELLED: The specific diagnosis of herpes simplex virus type 1 and 2 infections has an extreme importance in acute infections of central nervous system due to both availability of specific antiviral therapy and the possible serious consequences of the disease. AIMS: Evaluation of the relevance and interpretation of the results of PCR and the specific antibody testing. METHODS: Home made multiplex nested herpes simplex virus PCR and immunofluorescent IgM, IgA, IgG antibody tests were carried out in a total of 474 cerebrospinal fluid and 555 serum samples of 396 patients with acute infection of the central nervous system between 1. January, 2003 and 31. December, 2009. RESULTS: The herpes simplex virus etiology was verified in 21% of 396 patients (82 patients, mean 12 cases per year): 26 were diagnosed by both methods (32%), 41 by PCR only (50%), 15 by the detection of intrathecal antibody production only (18%) (p<0.0001). HSV type1 or 2 DNA remained detectable in 35% of the samples drawn after the 30th day of the disease. These patients were all younger than two years of age. CONCLUSIONS: 1. PCR increased the ratio of verified herpes simplex virus etiology in acute central nervous infections. 2. Testing the specific antibody response cannot be ceased even in the availability of PCR. 3. Herpes simplex virus type 1 or 2 DNA might persist in central nervous system in spite of the specific antiviral therapy especially in the infants. 4. Herpes simplex virus PCR can be repeated if an early sample is negative or if it is suspected false positive. 5. There is a need for cooperation between clinicians and virologists in the appropriate interpretation of the results and in finding etiology.