BAD WEATHER IMPACT OF TROPICAL DISTURBANCE

BAD Weather form of heavy rain, strong winds and high waves that hit most parts of the country lately to watch the whole society. The monitoring results indicate that the weather system disorders in our atmosphere these days due to the interference effects of warming temperatures of tropical sea surface waters of Indonesia, in addition to La Nina factor that has continued until today.

FLOOD cold lava which swept a number of areas in Magelang egency lately not a coincidence. There are several factors that cause flooding enormity Merapi lava in the western region, among which are characteristic of volcanic material deposits on the western side of Merapi, which is lighter and the high intensity rainfall in the Merapi area today.

Eruption of Mount Bromo (2392 m asl) in East Java has so far not shown signs of stopping. Mount Bromo activity was still high until the beginning of the rainy season at this time needs to be aware of all the citizens who live in the watershed are tipped in Bromo Caldera. The likelihood of the larger lava flooding can occur due to normal rainfall over the global impact of La Nina climate drift that has continued until today.

Tectonic earthquake measuring 5.3 on Richter scale (SR) rocked the city of Palu, Central Sulawesi, on Saturday (08/01/2011) at 16:15 pm (Figure 1). Meteorology, Climatology, and Geophysics (BMKG) mentions on its website, the center of the earthquake is located at 0.85 south latitude and 119.78 east longitude. That no potential tsunami earthquake that occurred at a depth of 23 kilometers with a distance of 9 kilometers northwest of Palu.

Lahar flood that occurred in a number of rivers in Merapi on Monday (3 / 1) is the largest Lahar flood after Merapi volcano eruption. However, according to reports from Center of Volcanic Investigation and Technology Development (BPPTK) Yogyakarta, up to nowdays volcanic materisl is estimated only 10 percent of the approximately 130 million cubic meters of volcanic material transported by lahar flood of Merapi. Therefore, to people who live in the watershed of Merapi volcano to be cautious, because the chances of greater flood lahar could occur given the higher rainfall intensity during the peak of rainy season in January-February 2011.

We determined locations of 140 shallow earthquakes at Bali Island and its surrounding recorded by a local digital regional seismograph network during 1991 to 1999. The networks consist of 8 short-period vertical component seismometers, covering a region of about 100 km by 200 km. Five sensors are located on Bali Island and 3 others are installed in the eastern end of East Java, Nusa Penida Island and western Lombok Island. The research aims to identify back arc thrust in Bali based on seismicity and focal mechanism. We used arrival time data, initial motion of P-wave, inversion method, HYPOINVERSE, SEISMIC and FOCAL softwares to locate hypocenter and determine fault plane solution parameters. There is a prominent belts of shallow earthquakes along the island arc. The shallow earthquakes show that back arc thrusting initiates north of Bali near -7.6o S at 1 km depth extends to -8.9o at 29.5 km depth beneath the southern coast of the Bali Island. All of fault plain solutions are thrust fault with slip vektor in the north direction and strike in the east-west direction, paralel with the islands arc.

The objective of this paper is to investigate the correlation between the increase of seismic activity in Yogyakarta region and Merapi volcano eruption. Data used in this study are earthquake parameters in Yogyakarta region and its surrounding, during the period of January up to November 2010. Data used in this study is the result of digital seismic network operated by Bureau of Meteorology, Climatology and Geophysics (BMKG).