Monday, December 29, 2014

VOLCANO MERAPI: An Overview

NAME:Volcano Merapi
LOCATION: Yogyakarta & Central Java
TYPE : Strato Volcano
CLASSIFICATION: Active Volcano A-Type
RECENT MAGMATIC ERUPTION: 2010
RECENT ERUPTION VEI SCALE: 4
PREVIOUS TREKKING ROUTE: Selo,Babadan,Deles & Kinaredjo




Merapi volcano located in two provinces of Indonesia: Yogyarta and Central Java.As Indonesian most active volcano,Merapi always do self destruction and change it self by erupting.The explosive eruption stage is frequently accompanied by pyroclastic flows that considered so far as most danger of Merapi volcanic hazard.The effusive eruptions were characterized by the occurrence of lava flows, the development of lava dome and the production of the "nuee ardente d'avalanche" that made the eruption type of this most active volcano previously so specific as it called Merapi Type.


First recorded eruption in historical time was on 1006 (Data Dasar Gunungapi Indonesia,1979),and recent eruption was recorded on Oct,2010.The recent eruption was more explosive eruption (VEI 4) that caused pyroclastic up 7 km vertically and reached area as far as 17 km,changed the Merapi Type eruption in to new type ones called "Plinian"(BPPTKG Yogyakarta),destructed it's summit then formed new sensational view crater 423 x 374 in size and 140 m in depth.Today summit Merapi is actually the highest point of it's crater's rim, it's high approx 2930 m,lower 38 m prior to huge eruption occured on Oct 2010.

The summit cone is visible from Merapi old crater called Pasar Bubrah approx altitude 2680 m, and accessible from crater rim previously called Puncak Bayangan (Summit Shadow) on it's right side.The summit access is slippery,and terrific steep crater rim.Therefore, hikers normally finalizes their hike until Puncak Bayangan or go further along left side of the Puncak Bayangan for more view of new crater of Merapi.

On pasca eruption Oct 2010, new volcanic phenomenon occurred at Merapi where the gas sulfur so dominant,and there'r minor eruptions per 1 - 2 years based on eruption frequency record:Feb,2012, Juny-Nov 2013, and Feb - Juny 2014.Such minor eruption has the power in blowing sulfur smoke mixed with ash/dust and spewing out from crater up 1 km in to sky,then caused the ash/dust rain in short of time around Merapi.

So far it's summarized that occurrence of several *"minor eruptions" were the follow up activity of Merapi pasca eruption 2010, as the causes of volcanic gas releasing from magma.If the release of this hot gas interacts with water of rainfall and formed steam pressure,then minor eruption could be occurred.

Regarding earthquakes factor to minor eruption, specially the huge ones,it's began by the increases of superficial earthquakes such superficial volcanic earthquake (VB),and other earthquake types: multiphase (MP) and low-high frequency (LHF),there's no records of VA,and LF.It's interpreted that "minor eruption" process was superficial volcanic process.The absent of VA and LF indicated there's no new magma supply.Earthquake type of low-frequency (LF) at Merapi always exist before magmatic eruption as indication of the present of fluid magma flow.


* Another term of minor eruption is Phreatic Eruption, a non magmatic eruption.

NOTES:
Photos Contributors: Olenk Ambo Upe & Yanto Turgo
Stuff Contributor: Olenk Ambo Upe



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