Seismic microzonation using microtremor measurement for natural disasters mitigation of earthquake at regions Singaraja city the province of Bali Indonesia

Lantu, Sabrianto and A. Tenri Awali

A research has been done to micro zoning the prone area of natural disasters at Singaraja city the province of bali by using the mikroteremor method. The aim of this research was determine the dominant frequency, the velocity of S wave at 30 m depth and amplification an earthquake in the study areas and maping the prone earthquakes in the study areas to mitigate the risk of earthquake. Research locations is at coordinates 8.16768o N tol 8.08759O N and 115.06535o E to 115.140820 E at the Singaraja, district of Buleleng, Bali. The data used obtained from the center of vulkanologi research and disaster geology mitigation geology as muchy as 82 points. Every point recorded for 20 minutes. From the analysis and data interpretation obtain that S waves velocity at the 30m of depth is 260.5 m / s -- 295 m / s, the dominant frequency dominant be range of 1.52 Hz - 7.34 Hz, with amplification between 1 6 - 6 1 times. The areas with high Vulnerability located at the northwestern of study areas.

Assessment of relation between large earthquakes and ionosphere electron density using GPS data: A case study, Azerbaijan earthquake

Mohammad Armande and Tohid Malekzade

The ionosphere is a part of the earth's atmosphere, laying at the heights between 50 km and 2000 km above the earth's surface, and consisting of several layers identified by differences in the level of ionization. GPS ionospheric error consists of the satellite signal propagation delay collected during the passage of the ionosphere. The GPS ionospheric time-delay is directly proportional to the number of electrons per unit area encountered during the passage of the ionosphere, usually referred to as the total electron content (TEC). TEC is a projection of electron density along signal path extending from the satellite to the receiver on the ground. The unit of TEC is TECU and 1 TECU equals 1016 electrons/m2. With the creation of local and regional networks, it is possible to acquire TEC in regular ionospheric grids. Using the regular ionospheric grids, the prediction of TEC in other parts of network is possible. Once the TEC is predicted, it is possible to correct ionospheric refraction in single frequency GPS receiver. In the customary two dimensional modeling techniques, ionosphere is approximated by a thin spherical shell of free electrons, located; 250 to 450 Km from the surface of the earth. The existing two dimensional methods of modeling the electron density can be classified to non-grid based and grid based techniques. The former modeling techniques are based on the least squares estimation of a functional model for certain types of observables derived from the GPS carrier phase and code measurements. So far, several different interpolation methods are used to predict TEC values. Spherical harmonics, spline interpolation, Gaussian processes are some of the examples used methods to predict TEC values for the locations where physical data are not exist. National cartographic center of Iran (NCC) is completing the Iranian permanent GPS network for geodynamics (IPGN). This network facilitates better understanding of tectonic deformation which allows estimating of future hazards and promoting scientific knowledge. The network consists of two parts: a) base network that covers the entire country of Iran, consisting of 41 GPS stations and b) three local networks in the most populated and active zones. The local networks are established in Tehran, Azerbaijan, and Khorasan with critical tectonic activities. GPS measurements of 12 successive days in August 2012 (DOY#219, 220, 221, 222, 223, 224, 225, 226, 227, 228, 229 and 230) have been used for modeling and processing. VTEC values at a temporal resolution of 15 min were derived from the dual frequency GPS receivers. According to results, it can be easily deduced that there are temporal variations in the electron content of the ionosphere. The characteristics which are the constituents of the ionosphere morphology are also reported elsewhere and confirmed by the analysis of the direct measurement techniques. The diurnal pattern of TEC exhibited a steady decrease from DOY#220. This decline has occurred at all hours. Also using these results can be clearly seen that the maximum value of TEC observed in daytime (8 UT), while the lowest occurred at nighttime (4 UT). It should be noting that at 2012/08/12 (DOY#224), the earthquake (Mw=6.4) occurred in this area. Based on the studies on impact of the earthquake in the value of TEC and ionosphere electron density, perhaps, earthquake is the main reason for reducing the value of TEC.

Coral bleaching is a tool for earthquake prediction

P. M. Mohan, M. Muruganantham and Vibha V. Ubare

Coral reefs are referred as a rainforest in the marine environment because of their high productivity and diversity of different fauna and flora even though it is noticed in nutrient poor waters. Recently, the major concern about these coral reefs are bleaching i.e. the corals are dying due to the raise of temperature with climatic change, considered as one of the major hazard in the marine environment. Similarly, the earthquake is another major hazard happening in terrestrial as well as marine environments, however, the human loss happening mainly in the terrestrial environment. So, people are working hard to understand and try to predict the earthquake occurrence early enough to mitigate its hazard and save the human community. To date scientist are not successful in this task. Now, an attempt has been made to predict earthquake through the coral bleaching process. From 1983 to 2015 were correlated with nearest time period earthquakes and a systematic pattern with earthquake occurrences along with the coral bleaching were established. This coral bleaching might have occurred due to the radon gas exhalation from the nearest earth surface which was triggered due to the stress or strain of the nearest period earthquake. Based on this concept, it may be predicted that if earthquake scientist monitor the coral bleaching, the earthquake occurrence between 100 and 3000 km in the surrounding areas may be predicted within 15 to 30 days. This was once again confirmed, in the 10th April 2016 Afghanistan earthquake, as a precursor during 14th March 2016 coral bleach was noticed in Andaman and Nicobar Islands. So, monitoring of coral bleaching may be the best possible, closet predication tool or precursor available till date. Further, it may also suggest from this study that the coral bleaching is not due to climate change but because of earthquakes.