Work package number: WP2
Work package title: Land-based long-term multi-disciplinary monitoring
WP Leader: INGV
The aim of WP2 is the collection and integration of seismological, geochemical, and geodetic data to detect and model the interactions between fluids, crustal deformation and ruptures of the active tectonic structures of the Marmara area and, thereby, to contribute to its seismic hazard assessment. We aim to continue the monitoring of pre-earthquake transients by data recorded from the already established stations and networks. We will carry out in-situ measurements of fluid expulsions and their composition to recover information on changes in the fluid conduits and fluids chemistry, possibly related to pre-earthquake crustal deformation. Since some of the pre-earthquake transients might develop due to small nearby earthquakes, we aim to integrate existing seismological networks belonging to TUBITAK, KOERI and Kocaeli University (KOU). Additionally, we propose to develop multi-parameter data analyses and set-up of physical models that will enable us to correlate seismic and deformation activity with changes in near surface fluid (gas and water) emanation.
Description of work
The objective of this WP is to collect, manage, and integrate all kinds of useful data for monitoring of the Marmara region. As modifications of the fluid geochemistry are normally related to changes in the mixing ratios of fluids from different sources, the genesis of the circulating fluids (including both gases and waters) and their behaviour in time may allow us to discriminate modifications due to the development of the seismogenesis (crustal deformation) or to episodes of faulting activity (ruptures, seismic shocks). A geochemical survey carried out at regular time intervals (monthly rate) over the time span of the entire project (3 years) integrated with high-frequency data from the existing continuous multidisciplinary monitoring networks will allow us to collect enough data providing the necessary information to discriminate seismogenic-related changes from seasonal and anthropic-induced modifications. The temporal changes of geochemical, geodetic and seismic data will be integrated and modelled to gain a step-forward for a deeper knowledge of the development of the seismogenic processes induced by the NAFZ activity thus contributing to a better assessment of the seismic hazard of the area. Several observations have already suggested (Caracausi et al., 2005; Heinicke et al., 2009; Italiano et al., 2004, 2009a, b) that fluids are intimately linked to a variety of faulting processes. Over the Marmara sea area, fluids generated by deep crustal processes seem to be released by the recent faulting activity (e.g. Geli et al., 2008, Gasperini et al., 2012) supporting the necessity to take a look at the seismic hazard assessment by a multilateral view integrating information coming from seismic activity, fluids geochemistry and crustal deformation.
In this WP coordinated by INGV, 6 different institutions contribute: INGV with geochemical field work for sample collection and natural degassing, laboratory analyses, geochemical data validation and contribution to continuous monitoring and data integration and modelling. TUBITAK, KOERI, KOU, and GFZ with data from existing seismic networks. TUBITAK also with geochemical sample collection and laboratory analyses and contribution on natural degassing measurements, data validation, data sharing, data integration and modelling; GFZ with task 2 coordination, management of continuous monitoring geochemical stations (together with TUBITAK), development of existing network with new stations (together with INGV). Ifremer will promote the consideration in WP2 of the submarine, multi-parameter data collected within WP8. After the multi-parameter data integration, all partners will contribute, to data analyses and modelling.
Task 1. Land-based geochemical and geophysical monitoring
The aim of the geochemical investigations is the assessment of the chemical and isotopic features of the discharged fluids to be used in an interpretative geochemical model aimed to constrain the fluids/faults relationships. The geochemical features will allow us to identify the following topics: 1) Chemical and isotopic characterization aimed to constrain the origin of the fluids 2) the main End-Members involved in the studied system (crustal, mantle-derived, radiogenic, etc.); 3) type and degree of water-rock and gas-water interaction processes, 4) Mixing proportions among the End-Members and their temporal changes. As such, the goal of task 1 is to build up a wide geochemical data set regarding fluids circulation, origin and interactions with the faults over the Marmara area. The data will be also combined with those from “Marmara poly-project” (1997). The geochemical survey will include the monthly collection of:
- gas samples for chemical analysis, isotopic analysis of carbon of both CO2 and CH4, isotopic analysis of the noble gases (3He/4He, 36Ar/40Ar);
- water samples to make chemical analysis of major, minor and trace elements, isotopic composition of oxygen and deuterium; and
- samples for dissolved gas analysis to make both chemical and isotopic analyses.
The analytical work can be done by both INGV and TUBITAK that share the samples, perform the analyses validation, and merge the collected data before moving them to the task 3 and 4 activities.
A general survey for natural degassing measurements of CO2, Rn, CH4 will be also carried out at the earlier stage of the project. Since the discharge of any fluid at the surface is an indication of ground discontinuities, the preliminary results, proposed on GIS-generated maps, will allow us to recognize possible hidden fault traces even in the absence of other surface evidences. This aspect might become a very relevant feature of a faulted area to indicate high-risk of future superficial ruptures in coincidence of seismic events.
Task 2. In-situ measurement of fluid expulsions using existing/improved systems
The existing in-land continuous fluid monitoring network is composed of automatic stations equipped with different probes as a function of the specific features of the selected site (e.g. radon soil degassing equipment, temperature and conductivity of thermal springs within the TUBITAK network covering the whole Marmara region; fluid pressure and water level within the local ARNET operated by GFZ). ARNET is located on the Armutlu peninsula SW of Istanbul centred on the western end of the rupture of the 1999 Izmit earthquake. The automatic stations can also perform real-time data transmission and/or in situ data storage. Based on the results of the fluid mapping (task 1) and a critical evaluation of the existing time-series of continuous measurements, we will choose key sites to install and test new fluid monitoring equipment (e.g. instruments to measure the content of dissolved gases developed at INGV) to be integrated with the existing TUBITAK network for radon and springs measurements and the fluid pressure sites of ARNET.
Task 3. Integration of real-time networks data for Marmara area
Around the Marmara Sea, KOERI, TUBITAK, KOU and GFZ independently run different networks (see WP4). In this task, the main goal is to integrate real time data which comes from different networks. The starting point for this task is the collection of existing data from the continuous seismic, geochemical (spring waters and soil radon) and geodetic networks. For example, TUBITAK networks include more than 40 seismological, 35 geochemical and 21 GPS sites. The ARNET (Armutlu Network) includes 23 broadband and short period seismic stations plus 6 accelerometers and 5 hydrothermal stations. All collected data will be organized in a joint database. The existing GPS data will be evaluated, after a daily data cleaning and pre-analysis (to remove the atmospheric noise) and will be ready to serve for the MARsite project. This integration helps in understanding the anomalies in the time series, detect the false anomalies, and will be a powerful tool to interpret data sets together. Briefly, the main output will be a combined data catalogue of the multi-disciplinary observations ready to be processed in Task 4.
Task 4. Multi-parameter data analysis, physical models for correlating geochemical, geodetic and seismic activity
Data from the land based seismological, geochemical (spring waters and soil radon) and geodetic (microgravity, tilt, GPS) measurements already integrated in a database (task 3) will be analysed by different statistical approaches to remove periodical changes (e.g. earth-tide effects) thus discriminating changes and behaviours closely related to possible speed-up of seismogenic process. Marine data from the fault zone collected within WP8 will also be considered in the present task. Possible pre-earthquake „short-term‟ anomalies can be recognized and interpreted. Multi-parameter interpretative models can be proposed to contribute to the hazard assessment of the Marmara region.