Multi-station GPS-TEC Analysis of Pre-seismic Ionospheric Anomalies: The 2023 Kahramanmaras Earthquakes

Öz

This study investigates pre-seismic ionospheric disturbances preceding the February 6, 2023 Kahramanmaraş earthquake sequence (Mw 7.8 and Mw 7.5) using GPS-derived Total Electron Content (TEC) data from 15 TNPGN-Active stations. The IONOLAB-FFT algorithm was applied to analyze frequency and duration characteristics of ionospheric disturbances during the five-day pre-earthquake period. Cross-correlation analysis reveals systematic temporal evolution, with near-epicentral stations showing pronounced variations. The Ekinözü station (EKZ1), 15.5 km from the Mw 7.5 epicenter, exhibited the most dramatic correlation drop from ~0.95 to ~0.78. Experimental Probability Density Function analysis demonstrates progressive spectral evolution from baseline conditions to increasingly anomalous signatures, with broadened frequency spectra at near-epicentral stations indicating multiple disturbance mechanisms. Duration analysis reveals bimodal distributions at stations closest to epicenters, suggesting coexistence of short-duration acoustic-gravity waves and longer-duration electromagnetic disturbances. Significant ionospheric anomalies begin 2-3 days before the earthquake sequence, with most pronounced changes occurring 24-48 hours prior to the main shock. The analysis establishes clear distance-dependent relationships, with optimal detection sensitivity within 50-100 km of seismic sources. Results provide compelling evidence for Lithosphere-Atmosphere-Ionosphere coupling mechanisms and demonstrate potential applications in earthquake monitoring systems.

Anahtar Kelimeler

• Pre-erathquake Ionospheric Anomalies
• GPS-TEC Analysis
• Kahramanmaras Earthquakes
• Spectral Precursors

Sismik Öncesi İyonküre Anomalilerinin Çok İstasyonlu GPS-TEC Analizi: 2023 Kahramanmaraş Depremleri

Öz

Bu çalışmada, 15 TUSAGA-Aktif YKS istasyonundan kestirilen Toplam Elektron İçeriği (TEİ) verileri kullanılarak 6 Şubat 2023 Kahramanmaraş deprem dizisi (Mw 7.8 ve Mw 7.5) öncesindeki deprem öncesi iyonküre bozulmalar araştırılmıştır. IONOLAB-FFT algoritması, beş günlük deprem öncesi dönemde iyonküre bozulmalarının frekans ve süre özelliklerini analiz etmek için uygulanmıştır. Çapraz korelasyon analizi sistematik zamansal evrimi ortaya koyarken, merkez üssüne yakın istasyonlar belirgin değişimler göstermiştir. Mw 7.5 merkez üssünden 15.5 km uzaklıktaki Ekinözü istasyonu (EKZ1), ~0.95'ten ~0.78'e en çarpıcı korelasyon düşüşünü göstermiştir. Deneysel Olasılık Yoğunluk Fonksiyonu analizi, temel koşullardan giderek artan anormal işaretlere doğru ilerleyen spektral evrimi ortaya koyarken, merkez üssüne yakın istasyonlarda genişletilmiş frekans spektrumları çoklu bozulma mekanizmalarına işaret etmektedir. Süre analizi, merkez üslerine en yakın istasyonlarda bimodal dağılımlar ortaya koyarak kısa süreli akustik-yerçekimi dalgalarının ve daha uzun süreli elektromanyetik bozulmaların bir arada var olduğunu ileri sürmektedir. Önemli iyonküre anomalileri, deprem dizisinden 2-3 gün önce başlar ve en belirgin değişimler ana şoktan 24-48 saat önce meydana gelir. Çalışmanın analiz sonuçları, sismik kaynakların 50-100 km yakınında optimum algılama hassasiyetiyle net mesafeye bağlı ilişkiler ortaya koymuştur. Sonuçlar Litosfer-Atmosfer-İyonküre bağlaşım mekanizmaları için önemli bulgular sunmuş ve deprem izleme sistemlerinde potansiyel uygulamaları işaret etmiştir.

Anahtar Kelimeler

• Deprem Öncesi İyonküre Bozulmaları
• YKS-TEİ Analizi
• Kahramanmaraş Depremleri
• İzgel Öncüller

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