Temperature and heat flux changes at the base of Laurentide ice sheet inferred from geothermal data (evidence from province of Alberta,Canada)

International Journal of Earth Sciences - Using a previously published temperature log of the 2363-m-deep borehole Hunt well (Alberta, Canada) and the results of its previous interpretation, the...     

On the Origin of Quasi-Periodic Temperature Variations in Kun-1 Well (Kunashir Island)

The results of temperature monitoring in the 300-m kun-1 well (Kunashir Island) in 2011–2015 are considered. Quasi-periodic temperature variations with an amplitude of up to 0.3°C and a variation period of 14–26 h were added from November 2011 to the previously observed temperature variations caused by tidal deformations, free thermal convection, and deformation processes associated with the preparation and occurrence of tectonic earthquakes. Five cycles of such variations lasting from 2 to 6 months have been recorded. Each cycle was initiated by an earthquake with magnitude M > 2.5log(R), where R is the epicentral distance (km). According to their characteristics, the variations are unique and have not been described previously. Assumptions have been made about the possible connection of the registered variations with the inertial currents of the ocean or with hydrothermal processes in the Earth’s subsurface. The phenomenon discovered requires further study not only as an object of fundamental science, but also as a feature of an earlier unknown type of geodynamic activity that can be a significant threat to the regional population.     

Temperature Response to External Radiative Forcing: Verification of a Simple Model

Izvestiya, Atmospheric and Oceanic Physics - A model of ground surface heat exchange explaining the observed delay in temperature response to external radiation variations has been proposed....     

On the nature of temperature variations in borehole kun-1 (Kunashir Island)

The study presents the result of continuous temperature monitoring in a 300 m deep borehole located on the Pacific coast of the Kunashir Island. Temperature variations at of 20–240 m depths with periods from a few tens of minutes to a few tens of days and amplitudes in the order of thousandths to tenths of degree are found to result from three main causes: tidal variations of groundwater level in the borehole, natural convection in the borehole, and nonperiodic and spatially heterogeneous changes of the pore pressure resulting in the appearance of an anomalous subsurface fluid regime and generating crossflow between the different aquifers through the annular space. Joint analysis of temperature and seismic data revealed that shallow-focus (up to 30 km) earthquakes with M > 5 occurred southeast of the seismic station created more expressed temperature response at 240 m depth. This response has the form of a 0.05–0.3 K temperature drop, which precedes a seismic event within a period of a few hours to a few days. Tidal analysis of borehole temperature measurements can be used to calculate the strain sensitivity and the method of borehole temperature monitoring can be used to investigate the tectonic regime of the Earth’s crust.     

Climate reconstruction in the Urals from geothermal data

Results of paleoclimatic analysis of geothermal data in the Middle and Southern Urals for different time intervals are presented. Climate reconstruction for the past millennium was made using data from 44 boreholes, and the magnitude of the Wurm–Holocene warming event was estimated based on data from two deep boreholes. The method of functional space inversion was used. The resolution of the method for reconstruction of various climatic events in the past was investigated. Parameters specified a priori and the required duration of the period to be reconstructed were chosen from the results of numerical modeling. According to the inversion results, the ground surface temperature at the maximum of the Medieval Warm Period in 1100–1200 was approximately the same as the present temperature, and at the minimum of the Little Ice Age around 1720, it was 1.2–3 °C lower than at present. The subsequent temperature rise was more pronounced in the past century. The magnitude of the Wurm–Holocene warming event, reconstructed using data from two deep boreholes is 10–11 °C.     

A New Climate Response Model for the Orbital Tuning of Pleistocene Climate Reconstructions

Izvestiya, Atmospheric and Oceanic Physics - This paper describes a new approach to orbital tuning for the adjustment of proxy-based paleoclimate chronologies; the approach involves the...     

Temperature changes in the KUN-1 borehole, Kunashir Island, induced by the Tohoku Earthquake (March 11, 2011, M = 9.0)

The results of continuous (September 2010?CSeptember 2011) temperature monitoring in the 300-m-deep borehole on Kunashir Island are presented. There were several earthquakes, including the Tohoku one (March 3, 2012, M = 9.0), during the observation period, and they produced a significant coseismic response in the temperature field. The Tohoku earthquake was preceded by a constant decrease in temperature at the depth of 240 m with a mean rate of 0.02 K per month. The coseismic response was manifested in an abrupt (in à day) growth of temperature by 1.2 K. The relationships between the earthquake characteristics (magnitude, epicentral distance) and the amplitude of the coseismic temperature response in the borehole have been estimated. The deformation mechanism of the temperature response to earthquake preparation and implementation processes is suggested.