Chile quakes extended days

Researchers present new results of geodetic measurements

Destruction in the Chilean city of Concepción © TU Wien
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On February 27, 2010, one of the strongest earthquakes of recent decades destroyed large parts of the third-largest Chilean city Concepción and its surrounding area. Earth scientists have now revealed more amazing consequences of the magnitude 8, 8 earthquake. For example, the natural disaster slowed the Earth's speed slightly - and made the days longer. However, only by 0.3 microseconds. However, these changes are not noticeable to us humans.

The scientists at least partially contradict calculations made by NASA

had already done shortly after the earthquake.

Researchers at the Vienna University of Technology (TU Wien) and their colleagues around the globe have been using geodetic measurements to investigate the effects of the severe quake at the end of February 2010 off the Chilean coast. These allow, for example, to determine the deformation of the earth's crust and the displacement of the continental plates with very high accuracy.

South American plate pulled apart

The GPS station in Concepción, which ran smoothly during and after the earthquake, has measured a displacement of several meters in a westerly direction. According to the findings of the researchers, the entire South American plate was not only "wandered west" but also "pulled apart". display

Horizontal displacements measured with GPS © TU Wien

"Observations with the radio telescope in Concepción will provide further important information on the plate movement by means of the method of Very Long Baseline Interferometry (VLBI), " suspects Johannes Böhm, head of the VLBI group at the Institute of Geodesy and Geophysics of the Vienna University of Technology. The current results of the VLBI evaluations at the institute have already confirmed the displacement of about three meters to the west and 0.65 meters to the south.

The days are getting longer

Experts suspected shortly after the natural disaster that the earthquake also affected the Earth's rotation. The mass shifts within the earth's crust caused by the earthquake affect both the Earth's rotational speed and the direction of the axis of rotation, where they contribute to pole movement. With information on the strength of the earthquake and the resulting deformations, the Institute of Geodesy and Geophysics has calculated the effect on the Earth's rotation.

Initial results show that the Earth's rotation speed has slowed slightly and days have gone longer by 0.3 microseconds. In addition, the pole movement will be different in the coming months by about 2.6 millibose seconds, which corresponds to seven centimeters on the earth's surface, than without the impact of the earthquake in Chile.

Professor Harald Schuh from the Vienna University of Technology and President of the Commission "Rotation of the Earth" within the International Astronomical Union (IAU) therefore confirms that "statements that are a leap forward" Relocation of the axis of rotation could be assumed, therefore not correct.

The radio telescope TIGO, Concepci n / Chile with the working group of the Vienna University of Technology (from left: Robert Heinkelmann, Johannes B hm, Professor Harald Schuh, J rg Wresnik) Vienna University of Technology

Not only earthquakes affect the Earth's rotation

Currently, observations are being made using global satellite systems such as the American GPS or the Russian Glonass and also the VLBI method to confirm the effect of the earthquake on the Earth's rotation.

This is not so easy, as there are many other factors besides Earthquakes, such as strong wind currents or ocean tides, emphasizes Tobias Nilsson, who is responsible for the relevant work is responsible for the simulation model. The geodesics' research work aims to improve the prediction and / or possibilities for short-term warning of natural catastrophes by means of modern geodesy measurement methods.

(idw - Technical University Vienna, 13.04.2010 - DLO)