January 28, 2016. EN. Misti , Nevado Del Ruiz , Marapi , Bromo .
January 28, 2016.
Misti, Perou :
El Misti is an active volcano, young, explosive and is considered as a volcano with increased risk in Peru, because of its proximity to the city of Arequipa (~ 17 km), which has at least a population of one million of inhabitants and a very important infrastructure in the vicinity (dams, hydroelectric plants, airports, mining centers, etc.). This volcano has had at least one major explosive eruption accompanied by about ten crises over the past 600 years.
The OVS–IGP, in the last 10 years, to obtain scientific results with the seismic monitoring in real time, developed a « base-line », which is now used to compare and track the daily seismic activity of the Misti volcano.
1. Volcanic and seismic monitoring:
Earthquakes type VT or fracture showed a decrease compared to the previous period (December 1 to 30, 2015). Their daily average occurrence rate dropped from 28 to 21 VT daily. During this period, only a small seismic swarm occurred on 22 of this month, with production of up to 72 earthquakes VTs. The most representative events are located below the main crater at depths ranging between 0.7 km and 1.5 km from the summit of the volcano. The biggest event VT of this period was held on January 13 than 12: 21HL (local time), with a magnitude of 1.6 ml, and was located ~ 1 km below the main crater.
Regarding the type of LP seismicity associated with fluid dynamics (gas and steam), the average daily attendance rate remains below 6 LP day. The highest occurrence of LP events during this period corresponds to January 11, with a maximum of five LPs low energy (<1 megajoule). The tremor activity remained unchanged from the previous period. The most significant of these events date corresponds to January 3 with 4 tremors. These events were characterized as short-term (<5 min) and low power (<0.5 MJ).
In short, the activity of Misti continues to show low levels (normal). This activity is associated with rock fracturing process (VT) and, to a lesser extent, events related to fluid dynamics (LP and tremors).
2. Satellite monitoring:
Thermal anomalies: The Mirova system (www.mirova.unito.it) from the University of Turin (Italy) has not detected thermal anomalies on the Misti volcano for that period.
Anomalies of SO2: The satellite system GSDM–NASA (http://so2.gsfc.nasa.gov/) « EOS Aura » did not notice any major SO2 gas density anomalies (magmatic gases) on the Misti Volcano .
Source : IGP
Photos : explore Peru , Nature-perou.
Nevado Del Ruiz , Colombia :
Subject: internal activity level of the Nevado del Ruiz volcano.
The level of activity continues at:
Yellow activity level or (III): changes in the behavior of volcanic activity.
Regarding the monitoring of the activity of the Nevado del Ruiz volcano, the Colombian Geological Service reports:
During the last week, the volcanic system continued to show unstable behavior. The recorded seismic activity was mainly associated with the fracturing of the rock in the volcanic structure. This type of seismicity was located mainly in the Southwest areas, Northeast, North distal and in Arenas crater. The depths of earthquakes during the week ranged from 1.42 to 7.70 km. The maximum recorded was magnitude 1.2 ml (local magnitude), corresponding to an earthquake on January 24 at 12:04 (local time), located in the northeast sector of the Arenas crater at a depth of 2.82 km.
Seismic activity related to fluid dynamics in volcanic conduits, was characterized by the appearance of continuous tremors and earthquakes long period (LP). These two types of signals were mainly located near the Arenas crater and areas in South and Southeast of the volcano. The continuous tremor signal, had varying levels and low energy. Do not rule out that new episodes of high levels of energy of this signal and the output of gas and ash in the atmosphere can reproduce. These processes were accompanied by thermal anomalies, which were recorded by monitoring satellite images provided by the Italian universities (portal Mírová) of Turin and Florence. Moderate thermal anomalies on the 20, 22, 23 and 25 January, which have been identified near the Arenas crater, confirming the instability of the volcano.
The volcanic deformation measured from electronic inclinometers, global navigation satellite systems (GNSS) and satellite images, which record changes in tilt, position and shape of the volcano (respectively) in the last evaluated period, showed no significant changes.
The volcano continues to emit into the atmosphere a significant amounts of water vapor and gases, including sulfur dioxide (SO2), as has been estimated by the permanent stations SCAN DOAS installed in the volcano area and by satellite imagery.
The column of gas, steam and ash reached a height of 1300 meters above the summit of the volcano on January 22. The direction of the dispersion of the column is in line with the regime of prevailing winds in the region, who, during the week showed a predominant direction towards the west and northwest of the volcano.
It is considered that the volcanic system continues to evolve and new events may indicate an acceleration of the process, involving greater instability of it and consequently changes in activity level. While the instability of the volcano has been smoldering for more than five years, it is essential not to get used to an apparently monotonous behavior of the volcano and watch the official information that will be published by the Colombian Geological Service.
Source : SGC
Elevation 2891 m
PVMBG reported that on most days during periods of clear weather from 1 November 2015 to 19 January 2016 white plumes rose above Marapi as high as 250 m above the crater. A phreatic explosion at 2233 on 14 November generated an ash plume, and ashfall was noted in Panyalaian and Aia Angek on the SW flank. Seismicity fluctuated during 1-18 January; earthquakes indicating emissions, tornillo-type events, and shallow volcanic signals slightly increased. The Alert Level remained at 2 (on a scale of 1-4). Residents and visitors were advised not to enter an area within 3 km of the summit.
Gunung Marapi, not to be confused with the better-known Merapi volcano on Java, is Sumatra’s most active volcano. This massive complex stratovolcano rises 2000 m above the Bukittinggi plain in the Padang Highlands. A broad summit contains multiple partially overlapping summit craters constructed within the small 1.4-km-wide Bancah caldera. The summit craters are located along an ENE-WSW line, with volcanism migrating to the west. More than 50 eruptions, typically consisting of small-to-moderate explosive activity, have been recorded since the end of the 18th century; no lava flows outside the summit craters have been reported in historical time.
Sources : Pusat Vulkanologi dan Mitigasi Bencana Geologi , Gvp .
Photo : Pascal Blondé.
Bromo , Indonésia :
Elevation 2329 m
PVMBG reported that during 14-22 January brownish gray plumes from Tengger Caldera’s Bromo cone rose as high as 1.8 km above the crater. Seismicity fluctuated; the number of explosion signals increased and some shallow and deep volcanic earthquakes were recorded. The Alert Level remained at 3 (on a scale of 1-4); residents and visitors were reminded not to approach the crater within a radius of 2.5 km.
Based on information from PVMBG and satellite images, the Darwin VAAC reported that during 23 and 25-26 January ash plumes rose to altitudes of 3.6-3.9 km (12,000-13,000 ft) a.s.l. and drifted ENE, E, and SE.
Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi , GVP.
Photo : Sylvain Chermette ( 80 jours voyage)