Sunday, August 28, 2011

Lokon’s Mountain, North Sulawesi erupts again, August 28, 2011

The eruption of Mount Lokon has not abated. On Sunday, August 28, 2011 at 07.51 local time, another eruption occurred again following last month eruption. According to The Volcanic and Geological Disaster Mitigation Center (PVMBG) of Indonesia, the eruptions column reached 2,500 meters from Topaluan crater of the mountain. Series of volcanic tremors were recorded since 8pm on Saturday. With an extensive increasing numbers of earthquakes occurs about six hours prior to the eruption, 69 volcanic tremors were recorded during span time of 00.00-06.00 that day. Previously, after the July 14 eruption, the agency has lowered this mount's alert level from level IV to level III.

Images source: Detik

Friday, August 12, 2011

Indonesian government raises alert on Papandayan Mt, West Java

On Saturday, August 13, 2011 at 4am, local time, the Indonesian Volcanology Center has raised the alert from level II to Level III on Papandayan Mountain in West Java. The Center has set four levels increasing intensity of volcanic activity with level I for the lowest and level IV for the highest (alert level code chart).

The 2665 m (8,743 ft) Papandayan mountain is a complex stratovolcano with four large summit craters, the youngest of which was breached to the NE by collapse during a brief eruption in 1772 and contains active fumarole fields. Geographically, it’s located at the position of 7.32°S / 107.73°E. The closest major cities are Garut and Bandung. It began spewing gas on its three crater of Welirang, Manuk and Baladagama along with intense volcanic tremor and increase of rate of deformation for the last few days.

After its first historical eruption in 1772, in which collapse of the NE flank and produced a catastrophic debris avalanche that destroyed 40 villages and killed nearly 3000 persons, only small phreatic eruptions had occurred (1923, 1942) prior to an explosive eruption that began in November 2002.

Figure caption: Papandayan eruption in 2002 (source).

Tuesday, August 9, 2011

Important publication on earthquake forecasting developed by the International Commission on Earthquake Forecasting (ICEF)

An important report of the International Commission on Earthquake Forecasting (ICEF) entitled "Operational Earthquake Forecasting: State of Knowledge and Guidelines for Implementation", was recently published in Annals of Geophysics (vol. 54, num. 4, pp. 315-391, 2011; doi: 10.4401/ag-5350). Hopefully the report will be useful to other counties developing operational forecasting procedures and protocols, including Indonesia. The complete report can be freely downloaded from: this website.


State of Knowledge and Guidelines for Utilization

Authors: Thomas H. Jordan, Yun-Tai Chen, Paolo Gasparini, Raul Madariaga, Ian Main, Warner Marzocchi, Gerassimos Papadopoulos, Gennady Sobolev, Koshun Yamaoka, Jochen Zschau

Following the 2009 L'Aquila earthquake, the Dipartimento della Protezione Civile Italiana (DPC), appointed an International Commission on Earthquake Forecasting for Civil Protection (ICEF) to report on the current state of knowledge of short-term prediction and forecasting of tectonic earthquakes and indicate guidelines for utilization of possible forerunners of large earthquakes to drive civil protection actions, including the use of probabilistic seismic hazard analysis in the wake of a large earthquake. The ICEF reviewed research on earthquake prediction and forecasting, drawing from developments in seismically active regions worldwide. A prediction is defined as a deterministic statement that a future earthquake will or will not occur in a particular geographic region, time window, and magnitude range, whereas a forecast gives a probability (greater than zero but less than one) that such an event will occur. Earthquake predictability, the degree to which the future occurrence of earthquakes can be determined from the observable behavior of earthquake systems, is poorly understood. This lack of understanding is reflected in the inability to reliably predict large earthquakes in seismically active regions on short time scales. Most proposed prediction methods rely on the concept of a diagnostic precursor; i.e., some kind of signal observable before earthquakes that indicates with high probability the location, time, and magnitude of an impending event. Precursor methods reviewed here include changes in strain rates, seismic wave speeds, and electrical conductivity; variations of radon concentrations in groundwater, soil, and air; fluctuations in groundwater levels; electromagnetic variations near and above Earth's surface; thermal anomalies; anomalous animal behavior; and seismicity patterns. The search for diagnostic precursors has not yet produced a successful short-term prediction scheme. Therefore, this report focuses on operational earthquake forecasting as the principle means for gathering and disseminating authoritative information about time-dependent seismic hazards to help communities prepare for potentially destructive earthquakes. On short time scales of days and weeks, earthquake sequences show clustering in space and time, as indicated by the aftershocks triggered by large events. Statistical descriptions of clustering explain many features observed in seismicity catalogs, and they can be used to construct forecasts that indicate how earthquake probabilities change over the short term. Properly applied, short-term forecasts have operational utility; for example, in anticipating aftershocks that follow large earthquakes. Although the value of long-term forecasts for ensuring seismic safety is clear, the interpretation of short-term forecasts is problematic, because earthquake probabilities may vary over orders of magnitude but typically remain low in an absolute sense (< 1% per day). Translating such low-probability forecasts into effective decision-making is a difficult challenge. Reports on the current utilization operational forecasting in earthquake risk management were compiled for six countries with high seismic risk: China, Greece, Italy, Japan, Russia, United States. Long-term models are currently the most important forecasting tools for civil protection against earthquake damage, because they guide earthquake safety provisions of building codes, performance-based seismic design, and other risk-reducing engineering practices, such as retrofitting to correct design flaws in older buildings. Short-term forecasting of aftershocks is practiced by several countries among those surveyed, but operational earthquake forecasting has not been fully implemented (i.e., regularly updated and on a national scale) in any of them. Based on the experience accumulated in seismically active regions, the ICEF has provided to DPC a set of recommendations on the utilization of operational forecasting in Italy, which may also be useful in other countries. The public should be provided with open sources of information about the short-term probabilities of future earthquakes that are authoritative, scientific, consistent, and timely. Advisories should be based on operationally qualified, regularly updated seismicity forecasting systems that have been rigorously reviewed and updated by experts in the creation, delivery, and utility of earthquake information. The quality of all operational models should be evaluated for reliability and skill by retrospective testing, and they should be under continuous prospective testing against established long-term forecasts and alternative time-dependent models. Alert procedures should be standardized to facilitate decisions at different levels of government and among the public. Earthquake probability thresholds should be established to guide alert levels based on objective analysis of costs and benefits, as well as the less tangible aspects of value-of-information, such as gains in psychological preparedness and resilience. The principles of effective public communication established by social science research should be applied to the delivery of seismic hazard information.

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