China

  2010 AUG 31 - (VerticalNews.com) -- According to recent research from Tainan, Taiwan, "Between 2001 and 2005, the Disaster Prevention Research Center of National Cheng-Kung University established a groundwater observation network consisting of 16 wells. Most of these were located along active faults for research on earthquake-related groundwater changes."

  "They were selected mainly from among the 550 groundwater observation wells of the Water Resources Agency (WRA), which monitors and manages groundwater resources in Taiwan. The groundwater level was observed at a resolution of 0.2 mm at the wells. The depths of the well screens ranged between 80 and 252 m. Groundwater level data at six of the 16 wells were analyzed between 2003 and 2006 in an evaluation of such data for use in detecting earthquake-related groundwater level changes. The strain sensitivities of the groundwater level at these six wells ranged between 0.1 and 0.5 mm/10(-9), indicating that an analysis of groundwater level data at these six wells can detect volumetric strain changes on the order of 10(-9). Coseismic and/or postseismic groundwater level changes associated with 17 earthquakes in and around Taiwan whose magnitudes were >= 6 were also analyzed," wrote W.C. Lai and colleagues, National Cheng Kung University ...read more

  2010 AUG 31 - (VerticalNews.com) -- According to recent research published in the journal Earth Planets and Space, "An audio-frequency magnetotelluric (AMT) survey was undertaken at ten sites along a transect across the Hijima fault, a major segment of the Yamasaki fault system, Japan. The data were subjected to dimensionality analysis, following which two-dimensional inversions for the TE and TM modes were carried out."

  "This model is characterized by (1) a clear resistivity boundary that coincides with the downward projection of the surface trace of the Hijima fault, (2) a resistive zone (>500 Omega m) that corresponds to Mesozoic sediment, and (3) shallow and deep two highly conductive zones (30-40 Omega m) along the fault. The shallow conductive zone is a common feature of the Yamasaki fault system, whereas the deep conductor is a newly discovered feature at depths of 800-1,800 m to the southwest of the fault. The conductor is truncated by the Hijima fault to the northeast, and its upper boundary is the resistive zone. Both conductors are interpreted to represent a combination of clay minerals and a fluid network within a fault-related fracture zone," wrote S. Yamaguchi and colleagues, Osaka City University ...read more

  2010 AUG 31 - (VerticalNews.com) -- According to a study from Tokyo, Japan, "Since the 26 December 2004 Indian Ocean tsunami, the role of mangrove forests as natural defenses protecting coastal communities from tsunami disaster has been highlighted. However, some mangrove forests were destroyed by that tsunami."

  "They are expected to have lost their protective functions. In this study, we develop a fragility function to assess the mangrove trees' vulnerability, expressed as the damage probability of mangrove trees, based on field surveys and numerical modeling of the 2004 Indian Ocean tsunami in Banda Aceh, Indonesia. Based on the fragility function, we reconstruct a numerical model of tsunami inundation including the performance of mangrove forests in terms of reducing tsunami damage. The model reveals that a 10 year old mangrove forest in a 500 m wide area can reduce a tsunami's hydrodynamic force by approximately 70% for an incident wave of 3.0 m inundation depth and a wave period of 40 min at the shoreline. The model also shows, for a tsunami inundation depth of greater than 4 m, that a 10 year old mangrove forest would be mostly destroyed and that it would lose its force reduction capacity," wrote H. Yanagisawa and colleagues ...read more